Method for acquiring a set of images of a mouth object

Abstract

A method for acquiring a set of images covering a target belonging to a user's oral object, the method comprising the following steps: 1) presenting to the user, on a screen (12) and in augmented reality in the space of the oral object observed by an image acquisition device (10), a multidimensional symbol or a set of multidimensional symbols (24), the shape and / or position of each symbol being determined so as to indicate to the user at least one predetermined acquisition condition suitable for acquiring said image; 2) for each symbol, acquiring, with the acquisition device, said image when said at least one predetermined acquisition condition associated with said symbol is met, preferably when all the predetermined acquisition conditions associated with said symbol are met. Figure for the abstract: Fig. 5

Description

Title of the invention: Method for acquiring a set of images of a mouth object technical field

[0001] The present invention relates to a method for acquiring a set of images of an oral object, and in particular a dental object, notably a user's dental arch. The invention also relates to a device for implementing such a method. Previous technique

[0002] It is common practice to acquire a set of images covering a target located in a user's oral cavity, and in particular the user's dental arches, in order to analyze their dental situation, especially before establishing orthodontic treatment. An image "covers" a target when it represents at least part of that target. The image set "covers" the target when it contains images covering the target from different viewing directions, particularly to obtain precise three-dimensional information about the target.

[0003] An acquisition in a dental practice, or more generally from a dental care professional, can generate significant costs and stress for the user.

[0004] Alternatively, the user can acquire the dental images themselves, for example with their phone. To acquire an image, the user usually looks at themselves in a mirror, which can make precise positioning of their phone difficult. Furthermore, before consulting the gallery in which the images are saved, the user does not know if the images are of good quality, nor if they adequately cover the intended target. Even after consulting the gallery, they cannot accurately assess whether the coverage of the target by all the acquired images is sufficient. Finally, the acquisition can be laborious if the user is required to repeat it. Frustrated by these difficulties, the user may thus prematurely end the acquisition process.

[0005] There is a need to facilitate the acquisition of a set of mouth images covering a target, in particular all or part of the dental arches, while limiting the risk of incomplete or poor quality acquisition.

[0006] One aim of the invention is to meet this need. Description of the invention

[0007] The invention provides a method for acquiring a set of images covering, preferably with a coverage rate greater than or equal to a coverage threshold, a target belonging to a user's oral object, for example a set of images covering the incisors or teeth (target) of the user's dental arch (oral object).

[0008] According to a first principal aspect of the invention, the process comprises the following steps: 1) presentation to the user, on a screen and in augmented reality in the space of the oral object observed by an image acquisition device, preferably manipulated by the user, of a multidimensional symbol or a set of multidimensional symbols, the shape and / or position of each symbol being determined so as to indicate to the user at least one predetermined acquisition condition suitable for the acquisition of said image; 2) for each symbol, acquisition, with the acquisition device, of said image when said at least one predetermined acquisition condition associated with said symbol is met, preferably when all predetermined acquisition conditions associated with said symbol are met.

[0009] As will be seen in more detail later in the description, the shape of a multidimensional symbol in the space of the real scene observed by the acquisition device allows the user, when looking at the screen, to be informed and guided towards one or more acquisition conditions associated with said symbol and adapted to the acquisition of a desired image. A symbol presented in augmented reality thus provides particularly effective guidance information.

[0010] A process according to the first main aspect may also include, in particular, one or more of the following optional features: - in step 2), an image is acquired with the acquisition device only if at least one predetermined acquisition condition associated with at least one symbol is met, preferably if all the predetermined acquisition conditions associated with said symbol are met; - at least one defined symbol - a symbol axis, preferably an axis of revolution, an acquisition condition being an angular deviation between the optical axis of the acquisition device and said symbol axis of less than 20°, preferably less than 10°, preferably less than 5°, preferably substantially zero, i.e., a substantially perfect alignment of the optical axis of the acquisition device with said symbol axis, and / or - a dimension which, on the representation of the symbol on the screen, is variable depending on the distance between the acquisition device and said symbol in augmented reality, said acquisition condition being a specific predetermined value for said dimension or the belonging of said dimension to a specific predetermined range of values, for example a said dimension less than 1 mm; - prior to step 1), the user is taught, for each symbol, at least one predetermined acquisition condition associated with said symbol; for example, the user is told that, in order to acquire the set of images, for each symbol, they must align the symbol's axis as closely as possible with the optical axis of the acquisition device, and / or try to visualize the symbol on the screen so that said dimension is as close as possible to said specific value; - said teaching is carried out by means of a tutorial, the tutorial preferably allowing to progressively teach all the functionalities of the computer program executed for the implementation of the process, the tutorial being able to evolve according to updates; - in step 2), an image is automatically acquired with the acquisition device if predetermined acquisition conditions defining a position in space and / or an orientation of the acquisition device around its optical axis and including said at least one acquisition condition indicated by the symbol, are met; - in step 2), if we acquire, with the acquisition device, said image, - the appearance of said symbol is modified or said symbol is removed, and / or - a sound signal is emitted, and / or - we modify a score displayed on the screen and relating to a coverage rate of the target by the images already acquired and / or relating to the time for the acquisition of the images already acquired and / or relating to the quality of the images already acquired and / or relating to the usefulness of the images already acquired; - when the set of images has been acquired, the user is presented, on the screen, with a ranking determined according to said score; - the screen displays the symbols on preview images representing the actual scene observed by the acquisition device or on views of a model representing, like said preview images, at least said oral object or said target; - the screen displays a target in a fixed position on the screen, the target preferably having a constant shape, said symbol preferably having a shape complementary to the target when a predetermined acquisition condition associated with said symbol is met; - the target comprises more than 2, preferably more than 5 teeth and / or less than 32 teeth and / or the image set comprises more than 2, more than 5, more than 10 and / or less than 1,000 images taken under different respective acquisition conditions and / or the symbol set comprises more than 2, more than 5 and / or less than 100 symbols; - the symbols preferably each have an axis oriented towards the center of the user's mouth; - the symbols are preferably distributed in a plane, preferably in two planes, preferably in three planes, preferably so as to obtain images with axes of observation in the occlusal plane, in a plane inclined relative to the occlusal plane so as to obtain views from above relative to the occlusal plane and in a plane inclined relative to the occlusal plane so as to obtain views from below relative to the occlusal plane; - in the space of the oral object for augmented reality representation, the symbols are outside the user's mouth, so that the acquired images are extraoral.

[0011] In one embodiment, the symbol is a portion of the target surface, and a sighting point is displayed on the preview image, or an equivalent image, allowing visualization of the acquisition device's angle. The sighting point, aligned with the optical axis, is displayed on the target surface, in the same way that the sighting point appears on an object when it is aimed by a firearm projecting a laser beam onto the object, depending on the firing direction.

[0012] To orient the acquisition device correctly, the user must therefore aim the aiming point at the symbols represented on the surface of the target.

[0013] In this embodiment, the symbol can be a point or a surface. If it is a surface, its outline is deformed according to the shape and distance of the target surface onto which it is projected. The symbol can advantageously be used to indicate a distance of the acquisition device from the target and / or an orientation of the acquisition device around its optical axis.

[0014] The shape of the sighting point is not limiting.

[0015] The symbol may in particular be a vignette, that is to say a small image, attached to a tooth, for example a star as in a video game.

[0016] The set of symbols preferably defines acquisition conditions for the acquisition of - at least one image taken facing the user and / or at least one image taken to the user's right and / or at least one image taken to the user's left, preferably at least one image taken facing the user and at least one image taken to the user's right and at least one image taken to the user's left; and / or - at least one image taken facing the user on the one hand, and at least one image taken from above relative to the user and / or at least one image taken from below relative to the user on the other; preferably at least one image taken facing the user and at least one image taken from above relative to the user and at least one image taken from below relative to the user; and / or - at least one image taken with the mouth open and / or at least one image taken with the mouth closed.

[0017] The invention further relates to a device for implementing a method according to the first principal aspect of the invention, comprising - an image acquisition device, preferably in the form of a mobile phone; - a computer, preferably integrated into the acquisition device or in communication with the acquisition device, containing a computer program including program code instructions for - in step 1), arrange and present to the user one or more multidimensional symbols on a screen, preferably the screen of the acquisition device, in augmented reality in the space of the oral object, the shape and / or position of a symbol being determined in such a way as to indicate to the user at least one predetermined acquisition condition suitable for the acquisition of said image; - preferably, in step 2), only allow the acquisition, with the acquisition device, of said image if said at least one predetermined acquisition condition associated with a symbol is met, and / or command the acquisition device to acquire said image only if said at least one predetermined acquisition condition is met, and / or update a level of target coverage by the acquired images, and preferably compare the coverage level with a coverage threshold, and preferably display on the screen information on the coverage level and / or on the difference between the coverage threshold and the coverage level.

[0018] The acquisition device is preferably - a mobile phone and said screen is integrated into the mobile phone or - a device comprising a support equipped with a camera and intended to be held in contact with the user during the acquisition of the set of images, in particular in contact with the user's teeth and / or gums, the screen being integrated into the support or at a distance from the support.

[0019] According to a second principal aspect of the invention, the method aims to rapidly cover the target with a coverage rate greater than or equal to a coverage threshold, and the method comprises the following steps: a) acquisition of at least one image, preferably by the user, using an image acquisition device, preferably a mobile phone; b) updating the target coverage level based on said at least one image acquired in step a); c) if the coverage level is below the coverage threshold, - determination of guidance information towards suitable acquisition conditions for the acquisition, with the image acquisition device, of an additional image increasing the level of coverage; - presentation to the user of guidance information and, preferably, of an in training on the coverage level and / or on the difference between the coverage threshold and the coverage level, that is to say information enabling the user to know the progress of the acquisition of said set of images, and, - modification, by the user, of the position and / or orientation of the acquisition device according to the guidance information, and taken up again in step a), preferably in real time, the acquired images being preferably extracted from a film which the user views on a screen of the acquisition device.

[0020] As will be seen in more detail later in the description, determining guidance information based on a coverage rate updated in real time advantageously facilitates the acquisition of images of a user's mouth, and in particular the acquisition of dental images. Specifically, the user receives real-time guidance information, which makes acquisition more efficient, especially when the guidance information is chosen to direct the user towards optimal acquisition conditions that allow for the acquisition of an additional image, maximizing the increase in the coverage level.

[0021] Thanks to the guidance system, the user does not need to visit a dental professional, nor is the user supervised by a dental professional, to acquire the images. The images can advantageously be acquired under precise acquisition conditions, without any special training. In particular, they can be acquired by the user themselves or by a relative. Notably, the method facilitates the acquisition of images of a child's dental arches by a parent.

[0022] The presentation of information on the coverage level is also particularly advantageous because it effectively discourages the user from interrupting the acquisition before it is complete. It makes the acquisition process particularly enjoyable, as the user always knows how much further they have to go before acquiring the entire set of images. The acquisition can even be fun.

[0023] A process according to the second main aspect may also include, in particular, one or more of the following optional features: - the image is displayed on a screen, preferably on the screen of the acquisition device, preferably a mobile phone: - a representation of the target, - a representation of the portion of the target covered by one or more images acquired during step a) or earlier steps a), and - preferably, a representation of the oral object when the oral object includes other parts of the user's mouth than the target; - Guidance information and / or information on the coverage level and / or on the difference between the coverage threshold and the coverage level is / are presented in augmented reality in a preview image displayed on a screen of the acquisition device and representing the real scene observed by the acquisition device and / or in an image equivalent to the preview image representing a theoretical scene representing, symbolically or realistically, all or part of the elements of said real scene, in the same arrangement as in said real scene; - the equivalent image preferably includes a view of a model of at least a part of said real scene, a model being a three-dimensional digital model; - information on the level of coverage and / or on the difference between the coverage threshold and the level of coverage is presented in a spatial reference system so as to constitute said guidance information; - Information on the coverage level and / or the difference between the coverage threshold and the coverage level is presented on a representation of the target, - by applying an appearance, preferably a color or texture, to an area of ​​said representation that differs depending on whether said area is covered or not by at least one acquired image, or - by applying an appearance to a symbol representing a predetermined part of said target, for example a tooth, said appearance being different depending on whether said part is covered or not, preferably by making the symbol appear or disappear on the screen of the acquisition device, or - by applying an appearance to a symbol indicating at least one acquisition condition, said appearance being different depending on whether an image was acquired with said at least one acquisition condition or not; - the target comprises a set of teeth and / or soft tissues, the preview image or equivalent image is updated in real time, preferably on the user's mobile phone screen, covered teeth being specifically marked, by a symbol or by application of an appearance allowing them to be distinguished from uncovered teeth, a tooth being "covered" when its initial surface to be covered is covered; - a plurality of symbols are anchored, in augmented reality, in the real scene observed by the acquisition device, so as to appear on the preview image or on an equivalent image, each symbol being able for example to be anchored on a respective tooth of the user or to be anchored in such a way as to indicate to the user suitable acquisition conditions for the acquisition of the additional image; - the symbols are three-dimensional symbols according to the first principal aspect of the invention; - in step a), the user aims, with the acquisition device, at said symbol, preferably two-dimensional or three-dimensional, and when the target symbol is reached, preferably when it is at least partially superimposed on a fixed target displayed on the screen of the acquisition device, at least one image is acquired, preferably automatically, i.e. without specific intervention from the user; - the symbols are anchored on adjacent or non-adjacent teeth, in augmented reality, on the preview image or on an equivalent image, the symbols being able for example to be anchored regularly along the dental arch, for example every 2 or 3 teeth; - the symbols are anchored and / or shaped so as to define, optionally in cooperation with said target, predetermined acquisition conditions, preferably a distance of the acquisition device from the target and / or an orientation of the acquisition device around its optical axis and / or an angulation of said optical axis with respect to the target; - in step b), at least one image acquired in step a) is analyzed in order to identify a representation of the target on said image, preferably using a neural network, then the corresponding area is marked in the preview image, preferably by coloring it with a color associated with said target; - in step a), before or after image acquisition, the quality of the acquired or previewed image, i.e. displayed on the screen of the acquisition device, is evaluated, preferably at least the sharpness and / or contrast, and / or color balance of the image, and / or the distance of the acquisition device from the target and / or the orientation of the acquisition device around its optical axis and / or the angulation of said optical axis relative to the target, and the image is acquired and / or the coverage rate is updated only if the quality exceeds a predetermined quality threshold; - at step c), We test several acquisition conditions adapted for acquiring, with the image acquisition device, an additional image increasing the coverage level, then The guidance information is determined in such a way that it guides towards the optimal acquisition conditions, that is to say, conditions adapted for the acquisition, with the image acquisition device, of the additional image which most increases the level of coverage; - in step b), - we submit each acquired image to at least one initial neural network trained to detect the target's representation in the image and / or to an image processing algorithm adapted to detect the target's representation in the image, and to a second neural network trained to determine the position and orientation of the acquisition device during image acquisition, and therefore the direction of the optical axis of the acquisition device, i.e., the camera of the acquisition device, relative to the target and the distance of the acquisition device relative to the target, then - the said representation of the target is projected onto a model of the target or oral object, or "reference model", along a projection direction oriented, with respect to the said model, as the direction of the optical axis with respect to the target, the said representation of the target being virtually (i.e., theoretically) positioned, with respect to the reference model, as the acquisition device is positioned with respect to the target, then - the coverage rate is determined based on the surface area of ​​the reference model covered by said projection and by said projections carried out during possible previous step(s) b); - in step b), - we submit each acquired image to a first neural network trained to detect the representation of the target, or notable points of said target, on the image, and to a second neural network trained to recognize, from the representation of the target or the aforementioned notable points on the image, a corresponding area of ​​a reference image, then - the coverage rate is determined based on the surface area of ​​the reference image covered by said corresponding area and by said corresponding areas determined during possible previous step(s) b); - the acquisition device is - a mobile phone with a screen, preferably the user's own mobile phone or - a device comprising - a support equipped with a camera and held in place against the user during the acquisition of all images, preferably allowing the mouth to be opened and closed, preferably partially inserted into the user's mouth, preferably resting on the gums and / or teeth, and - a screen displaying the scene observed by the camera, said screen being integrated into the support or at a distance from the support; - in step a), the user views, in real time, on a screen of said mobile phone, the actual scene observed by the mobile phone or a corresponding theoretical scene, an image preferably being acquired automatically when the mobile phone observes the target under predetermined acquisition conditions, preferably under acquisition conditions determined at a step c) of the preceding cycle of steps a) to c); - in step c), the user is presented, preferably on the screen of the acquisition device, with a counter or gauge, preferably in the form of a progress bar, indicating the level of coverage and / or the difference between the coverage threshold and the coverage level, and / or - when the coverage threshold is reached, the user is presented, preferably on the screen of the acquisition device, with a score calculated based on the time taken to reach the coverage threshold and / or the quality of the images acquired, and / or the usefulness of the images acquired, and / or the user is presented, preferably on the screen of the acquisition device, with a ranking determined based on said score.

[0024] In a first principal embodiment, the guidance information comprises a set of symbols, positioned, in augmented reality, according to the respective images to be acquired. The set of images to be acquired includes one image for each symbol. In step a), the user must aim their mobile phone at the symbols and hit them, as in a video game. For example, each symbol can be anchored, in augmented reality, to a respective tooth, the target being made up of said teeth and / or soft tissues.

[0025] The symbols can be anchored according to desired acquisition conditions, for example on non-adjacent teeth, for example every two or three teeth.

[0026] A target can be displayed on the user's mobile phone screen. When the target overlaps with the symbol, the symbol is captured: an image is then acquired, preferably automatically, and the symbol is marked or disappears. The marking or disappearance of symbols provides information on the coverage rate. It also provides guidance information, as the user can easily identify symbols not yet captured on the preview image displayed on the mobile phone screen. They can then position the mobile phone accordingly. When all symbols have been captured, the image set covers all targeted teeth and / or soft tissues. The coverage level can be, for example, the ratio of the number of captured symbols to the initial number of symbols, i.e., before the start of the acquisition.

[0027] In a variant of this first main embodiment, the symbols are anchored and / or shaped so as to define, in cooperation with the target, predetermined acquisition conditions, preferably a distance of the acquisition device from the target and / or an orientation of the acquisition device around its optical axis and / or an angulation of said optical axis with respect to the target.

[0028] In one embodiment, the optional target is configured to be superimposed on several symbols simultaneously, for example two or three symbols. By For example, it comprises a plurality of elementary targets, such as circles, which must be simultaneously superimposed on a plurality of respective symbols. Advantageously, this superposition corresponds to a predetermined angle and distance of the acquisition device from the target. Preferably, the symbols of said plurality of symbols have an appearance, such as a color, specific to that plurality of symbols. For example, the user aims first to place the three green symbols in the circles of the target, then the three red symbols, and so on.

[0029] Equivalently, to impose a predetermined distance of the acquisition device from the target, the target and a symbol may have compatible dimensions, so that, when the user exactly superimposes the target and the symbol, the acquisition device and the target are at said distance.

[0030] The symbols of a plurality of symbols and the elementary targets are preferably different from one another, for example, bear different numbers. For example, the user aims to place the three symbols numbered 1, 2, and 3 in the circles numbered 1, 2, and 3 of the target, respectively. Advantageously, if the elementary targets are not aligned, this superposition can thus impose a predetermined orientation of the acquisition device around its optical axis.

[0031] Equivalently, to impose an orientation, the target and a symbol may have a shape that is not of revolution, for example a rectangular shape, preferably a shape without symmetry, so that the user can only superimpose, with the same orientation, the target and the symbol if the acquisition device is oriented along one or more predetermined orientations around the optical axis.

[0032] In particular, when symbols are used to impose an angulation, a distance or an orientation of the acquisition device, they are not necessarily associated with particular teeth, and in particular with teeth that must be covered.

[0033] In a second main embodiment, a view of a three-dimensional model of the target, for example, a set of teeth, is displayed on the mobile phone screen. In one embodiment, the user can modify this view, i.e., change the observation point of the model, using conventional model manipulation software. In a preferred embodiment, the view is modified according to the conditions under which the mobile phone observes the target, preferably according to the principles of augmented reality. The model can then be displayed, possibly transparently, superimposed on the preview image, or replace this preview image. When a preview image covers the target, an image is acquired, preferably automatically. The surface of the target represented in the acquired image is marked on the model, preferably colored, for example, green.The area of ​​the target still to be covered is re. Presented differently, for example colored red, the image allows the user to immediately visualize the coverage rate, such as the ratio between the green area and the total red and green area. The unmarked area guides the user towards acquisition conditions that increase the coverage rate.

[0034] In a variant of the second main embodiment, the view of the reference model is replaced by a reference image, for example a photo, for example a panoramic photo.

[0035] Preferably, a method according to the invention is implemented to acquire - at least one image taken facing the user and / or at least one image taken to the user's right and / or at least one image taken to the user's left, preferably at least one image taken facing the user and at least one image taken to the user's right and at least one image taken to the user's left; and / or - at least one image taken facing the user on the one hand, and at least one image taken from above relative to the user and / or at least one image taken from below relative to the user on the other; preferably at least one image taken facing the user and at least one image taken from above relative to the user and at least one image taken from below relative to the user; and / or - at least one image taken with the mouth open and / or at least one image taken with the mouth closed.

[0036] The invention also relates to a device for implementing a method of the invention, comprising: - an image acquisition device, a computer equipped with a camera, in particular a mobile phone or tablet, preferably a mobile phone, or a mirror equipped with a camera for acquiring the set of images, in particular for the implementation of step a); - a computer, which may be the acquisition device, preferably integrated into the mobile phone or in communication with the mobile phone, comprising a computer program including program code instructions for, according to the first principal aspect of the invention, presenting in augmented reality the three-dimensional symbols providing guidance information, and / or according to the second main aspect of the invention - updating the coverage level in step b), - the comparison of the coverage level with the coverage threshold, and - if the coverage level is below the coverage threshold, the determination of guidance information and the presentation to the user of guidance information and, preferably, information on the coverage level and / or on the difference between the coverage threshold and the coverage level, in step c); - preferably, a screen for displaying guidance information and, depending on the The second main aspect of the invention is information on the coverage level and / or on the difference between the coverage threshold and the coverage level, preferably on a computer screen.

[0037] In a preferred embodiment, the computer program is executed by the image acquisition device, the computer program being able to be integrated into specialized software, in particular specialized software for mobile phone or tablet.

[0038] The screen can be integrated into the image acquisition device. Preferably, the screen is the screen of a mobile phone or tablet.

[0039] Preferably, the screen and the computer program are integrated into the image acquisition device.

[0040] The user can then easily, without the intervention of a third party, and in particular without the intervention of a dental professional, by means of a simple mobile phone or tablet, acquire good quality images of the target covering the entire target.

[0041] The device may also include means of communication, in particular enabling the sending of the acquired image(s) and / or the receiving of a model or a reference image.

[0042] Of course, insofar as they are not technically incompatible, the necessary or optional characteristics of the various main aspects of the invention can be combined. Definitions

[0043] A “user” is a person for whom a process according to the invention is implemented.

[0044] “Dental care professional” means any person qualified to provide dental care, which includes an orthodontist and a dentist.

[0045] The term "arch" or "dental arch" means all or part of a dental arch, preferably comprising at least 2, preferably at least 3, preferably at least 4 teeth. According to the international convention of the Fédération Dentaire Internationale, each tooth in a dental arch has a predetermined number.

[0046] “Soft tissues” are the parts of the mouth covered with skin, such as the gums, palate or tongue, as opposed to teeth or an orthodontic appliance.

[0047] A soft tissue is an extra-skeletal supporting tissue, such as adipose tissue, tendons, ligaments, fascia, skin... (soft connective tissues) and muscle, vascular tissues and nerves (non-connective tissues).

[0048] A "retractor" (or "dental retractor") is a device designed to retract the lips or, more generally, to separate the lips from the teeth. Preferably, it comprises an upper and a lower rim, and / or a right and a left rim, extending around a retractor opening and designed to be inserted between the teeth and lips. In the working position, the user's lips rest on these rims, so that the teeth are visible through the retractor opening. A retractor thus allows the teeth to be observed without being obstructed by the lips. However, the teeth do not rest on the retractor, so the user can, by turning their head relative to the retractor, change which teeth are visible through the retractor opening. They can also change the spacing between their dental arches. In particular, a retractor does not press on the teeth to separate the two jaws from each other, but rather on the lips.In one embodiment, a retractor is configured to elastically separate the upper and lower lips so as to expose the teeth visible through the retractor opening. In another embodiment, a retractor is configured such that the distance between the upper and lower edges, and / or between the right and left edges, is constant. Retractors are described, for example, in PCT / EP2015 / 074896, US 6,923,761, or US 2004 / 0209225.

[0049] The term "computer" refers to a computing unit, which includes a set of several machines with computing capabilities. This unit may be integrated into a mobile phone, particularly the user's mobile phone, or be a PC or a server, for example, a server located remotely from the user, such as the cloud or a computer at a dental practice. Both the mobile phone and the computer include means of communication for exchanging information between them.

[0050] Typically, a computer includes, in particular, a processor, memory, a human-machine interface, typically comprising a screen, and a communication module for internet, Wi-Fi, Bluetooth®, or telephone network connections. Software configured to implement a method of the invention is loaded into the computer's memory. The computer can also be connected to a printer.

[0051] The method according to the invention (excluding the acquisition operation, carried out by the image acquisition device, and the operation of moving the image acquisition device, carried out by the user) is implemented by computer, preferably exclusively by computer.

[0052] A "real scene" consists of a set of elements observed simultaneously by the acquisition device. The view of the real scene observed by the acquisition device is conventionally displayed on a screen of the acquisition device, in the form of a "preview image" which is constantly updated in real time, like a film.

[0053] The preview image can be replaced or supplemented by an equivalent image representing, symbolically or realistically, a theoretical scene depicting all or part of the elements of the real scene, in the same arrangement as in the real scene, that is, in such a way that the represented elements are arranged relative to each other as in the real scene. The equivalent image is a view of the theoretical scene under observation conditions identical to those used by the acquisition device to observe the real scene and obtain the preview image. The contours of representations of physical elements on the equivalent image are therefore superimposable on the contours of said physical elements on the preview image. The equivalent image is chosen to exhibit maximum concordance with the preview image.

[0054] The preview image is preferably displayed on the screen of the acquisition device, but, in one embodiment, the equivalent image replaces the preview image on the screen. However, acquiring an image with the acquisition device at a given time consists of recording the preview image as it is displayed or as it would have been displayed if it were replaced by an equivalent image.

[0055] Augmented reality is a form of communication in which visual elements are added to an image representing a scene in a realistic or symbolic way. In particular, the visual elements can be added to a preview image representing the actual scene observed by the acquisition device or to an equivalent image.

[0056] A symbol is "anchored", in augmented reality, when it appears as fixed in the real or theoretical scene when the acquisition device moves relative to the real scene (and therefore modifies the image that is displayed by the acquisition device).

[0057] A symbol that appears in augmented reality can be a point, be two-dimensional (i.e., extend in a plane within the space of the oral object), or preferably, be three-dimensional (i.e., extend virtually in the three dimensions of the oral object's space). The way in which the two-dimensional or three-dimensional symbol is represented depends on the conditions under which it is virtually observed. For example, its size depends on the viewing distance. Preferably, the symbol is not spherical so that its representation also provides information on the angulation and / or orientation of the acquisition device around its optical axis. A symbol providing guidance information is preferably represented on the preview image or an equivalent image.

[0058] By "model" we mean a three-dimensional digital model. A model consists of a set of voxels.

[0059] A "tooth model" is a three-dimensional digital model of a tooth. A model of a dental arch can be segmented to define tooth models for at least some of the teeth, preferably for all the teeth represented in the arch model. The tooth models are therefore models within the arch model.

[0060] By "image" is meant a two-dimensional image, such as a photograph or an image extracted from a film. An image is made up of pixels. A "film" is considered to be a set of photographs. The number of pixels in an image is preferably greater than 100, 1,000, 10,000, 100,000, or 1,000,000, and / or less than 1,000,000,000.

[0061] An image represents a scene, realistically or not.

[0062] In particular, an image can represent a distorted mask resulting from the projection, preferably by the acquisition device, of an original mask. The original mask can be, for example, a grid or a set of studs, typically distributed regularly. The projection can be in visible or non-visible light, preferably in infrared light. The distortion of a portion of the original mask, for example, of a stud, resulting from its projection carries information about the distance between the area of ​​the scene onto which this portion of the original mask was projected and the image acquisition device. It can also provide information about the orientation of said area in space. The images used by Apple's Face ID software are examples of such images, also called "3D images."

[0063] An image acquired according to a method of the invention is preferably a photograph, possibly extracted from a film, realistically representing the observed scene, that is, as the human eye perceives it. It may represent a distorted mask, in particular superimposed on an image realistically representing the scene. It may represent only a distorted mask. Since the projection of the original mask is carried out on the real scene observed by the acquisition device, the image representing the distorted mask is also considered an image equivalent to the preview image.

[0064] The term "match" or "fit" between two objects, for example between the representations of a dental arch in two images, refers to a measure of the difference, or "distance," between these two objects. A match is maximal ("best fit") when this difference is minimal, in particular when the two images represent substantially the same elements in the same way, that is, in such a way that the representations of the elements in these two images are substantially superimposable in register.

[0065] The "acquisition conditions" of an image specify the position and / or orientation within the space of an image acquisition device, the image relative to the target and preferably the calibration of this image acquisition device (in particular the aperture, exposure time, focal length, and sensitivity). A symbol can indicate acquisition conditions suitable for a single position and orientation of the acquisition device. Alternatively, a symbol can indicate acquisition conditions corresponding to several positions and / or orientations of the acquisition device, to guide towards several potential images. For example, it can guide towards a predetermined observation axis without guiding to a particular position along that axis, thus allowing the user to acquire one or more images along that axis at various positions along it, as in the embodiment of [Fig. 3], for example.It can also guide towards a predetermined position in space, without guiding towards a particular orientation of the acquisition device around its optical axis, as in the embodiment of [Fig.5] for example.

[0066] The image acquisition device includes a camera for acquiring images, for example, photographs or a film. When reference is made to an observation of a scene by the acquisition device, it refers to an observation of the scene by the camera of the acquisition device. When reference is made to an optical axis of the acquisition device, it refers to the optical axis of the camera of the acquisition device, and so on.

[0067] An “angulation” is an orientation of the optical axis of the acquisition device with respect to the target.

[0068] An angle between two lines is an angle formed between two planes perpendicular to these two lines, respectively.

[0069] "Comprising" or "comprising" or "presenting" should be interpreted in a non-restrictive manner, unless otherwise indicated. Brief description of the drawings

[0070] Other features and advantages of the invention will become apparent upon reading the detailed description that follows and upon examination of the accompanying drawing in which: [Fig.1] [Fig.1] schematically represents the steps of a cycle of a process according to the second main aspect of the invention; [Fig.2] [Fig.2] represents an example of a device according to the invention; [Fig.3] [Fig.3] represents an example of the implementation of a process according to the second main aspect of the invention, in the first main embodiment; [Fig. 4] [Fig. 4] represents an example of the implementation of a method according to the first principal aspect of the invention and according to the second principal aspect of the invention, in the second principal embodiment; [[Fig.5]] [Fig.5] represents another example of the implementation of a process according to the first main aspect of the invention and according to the second main aspect of the invention, in the second main embodiment; [Fig.6] [Fig.6] represents a symbol of [Fig.5] as presented to the user when the predetermined acquisition conditions associated with the symbol are met; [Fig.7] [Fig.7] represents another example of the implementation of a process according to the first main aspect of the invention and according to the second main aspect of the invention, in the second main embodiment; [Fig.8] [Fig.8] schematically represents a three-dimensional symbol observed along its axis; [Fig.9] [Fig.9] schematically represents the steps of a cycle of a process according to the first main aspect of the invention; [Fig. 10] [Fig. 10] represents two examples of images equivalent to a preview image. Detailed description

[0071] An acquisition method according to the invention, illustrated in [Fig.1], is for example implemented by means of the device 1 illustrated in [Fig.2].

[0072] Device 1 comprises - an image acquisition device 10 equipped with a screen 12 and into which a computer program is loaded, and - a 14-inch computer equipped with an 18-inch screen.

[0073] The computer 14 may be separate from the acquisition device or, preferably, integrated into the acquisition device.

[0074] The computer 14 may also include digital communication means enabling the exchange of data 20, in particular with the image acquisition device 10, or even with a database 22.

[0075] The database 22 can also be integrated, partially or totally, into the acquisition device or the computer. It can, in particular, contain the acquired images, the reference model or reference image, the definition of the target and the oral object, or even a final model generated from the acquired images. It can also contain information relating to the predetermined acquisition conditions associated with each symbol.

[0076] In a preferred embodiment of the invention, the image acquisition device 10 is a mobile phone or a tablet. The screen 12 of the acquisition device is configured to display the guidance information, and preferably Information on the coverage level and / or the difference between the coverage threshold and the coverage level. Alternatively, or in addition, this information can be displayed on screen 18 of the computer.

[0077] The image acquisition device can also be a mirror equipped with a camera.

[0078] Device 1 is used to implement a method according to the invention:

[0079] The target has a predetermined "initial surface to be covered", that is to say, a surface which the implementation of the process is intended to cover.

[0080] The "covered area" is the portion of the initial area to be covered that, at some point during the process, has already been covered, i.e., represented on at least one acquired image. The "area still to be covered" is the portion of the initial area to be covered that, at some point during the process, has not been represented on any acquired image.

[0081] The surface of a target may include elementary surfaces of several respective identifiable organs, for example, several teeth. An organ may be described as "covered" or "still to be covered" depending on whether all of its elementary surface is covered or not.

[0082] The oral object may include, or be made up of, the tongue and / or the palate and / or one or two gums and / or one or two dental arches, and / or one or more teeth. Preferably the oral object is a dental arch.

[0083] The oral object may also be an orthodontic appliance, for example a multi-bracket appliance, vestibular or lingual, an orthodontic splint, preferably invisible, an auxiliary, for example a peg, a button or a screw, a functional education device, for example to modify the positioning of the tongue or to treat sleep apnea.

[0084] A target can be the oral object. It can also be a region of interest of the oral object, in particular a region that has been identified as a region at risk or a region being monitored, for example in the context of orthodontic treatment or periodontal monitoring, a region that has been poorly scanned, for example during a previous appointment with a dental professional, or a region that has changed.

[0085] In a preferred embodiment, the oral object is a dental arch and the target consists of one or preferably several teeth of said dental arch.

[0086] The target is identified before the method is implemented and the computer is informed accordingly. For example, the computer is informed that it needs to acquire a set of images covering teeth 10 to 14, or it is provided with an image or model of a dental arch on which the representation of the target has been identified.

[0087] The image or model used to identify the target may be generic, that is, usable by several users. They may be selected from a database, the database being accessible via communication means Digital communication. A generic model can be a typodont. Preferably, the generic model or image is chosen so that it represents a target with a shape close to the user's target, thus improving the accuracy of the process. If the target belongs to a dental arch, the model can be generated by implementing a process that arranges tooth models, for example, as described in European application no. 18184486.

[0088] The model or image used to identify the target is preferably a model or image representing the user's target, acquired prior to the implementation of the process.

[0089] Each area of ​​the target that is represented on an acquired image is said to be "covered" by that image. The union of the areas represented on at least one acquired image is the "covered area".

[0090] The image set is considered sufficient to cover a given target when the level of coverage by the acquired images reaches a coverage threshold.

[0091] The coverage threshold thus defines, directly or indirectly, a percentage of the initial area to be covered which is considered sufficient for the acquisition to be terminated, that is to say, for the acquisition to be considered complete.

[0092] A coverage threshold of 100% requires, for example, that the entire surface of the target be represented on at least one acquired image.

[0093] The coverage threshold can be determined so that the image set is sufficient to view the target from predetermined angles, including from any angle.

[0094] The coverage threshold is preferably predetermined, before the first step a).

[0095] The coverage threshold may be greater than 50%, 70%, 80%, 90%, or 95% of the target area. Preferably, the coverage threshold is greater than 95%.

[0096] The coverage level is a measure of the progress of the acquisition relative to the coverage threshold. Before the acquisition of a first image, the coverage level is therefore zero. The level of progress increases progressively as the cycles of steps a) to c) progress.

[0097] The coverage level can be, for example, the ratio of the covered area to the initial area to be covered. If 30% of the initial area to be covered is covered, the coverage level is thus 30%.

[0098] The coverage level can also be, for example, the ratio of the covered area to the area still to be covered, consisting of all the areas of the target that are not represented in any acquired image. If 30% of the initial area to be covered is covered, the coverage level is thus 30% / 70%.

[0099] If the oral object comprises a set of teeth, the coverage level can be further defined as the ratio of the number of teeth covered to the total number of teeth in said set. A tooth can be considered covered, for example, if at least 90% of its external, occlusal, or vestibular surface is represented in the acquired images; better still, if at least 95% of said tooth surface is represented in the acquired images; and even better, if the entire tooth surface is represented in the acquired images.

[0100] A tooth can alternatively be considered as covered when one or more notable points of that tooth are represented on at least one acquired image.

[0101] In the embodiment described above, the objective was considered to be to cover a surface of the target.

[0102] By extension, in one embodiment, the objective is to acquire a set of images under respective acquisition conditions defined by symbols, preferably multidimensional. The set of symbols defining each of the acquisition conditions for one or more respective images can then be considered, at the beginning of the implementation of a method according to the invention, as an "initial area to be covered." The set of symbols defining, at a given time, acquisition conditions under which an image has already been acquired can be considered a "covered area," the number of these symbols defining a "coverage level," the "coverage threshold" being a minimum number of these symbols. Finally, the set of symbols defining acquisition conditions under which an image remains to be acquired can be considered an "area still to be covered."

[0103] By extension, in one embodiment, the objective is to acquire a set of images partially representing the target, for example, representing, for each tooth of the target, notable points such as mesial-distal points, cusps, the free edge, cervical points, or the centroid of a tooth face. The set of notable points of the target can then be considered, at the beginning of the implementation of a method according to the invention, as an "initial area to be covered." The set of notable points of the target already represented on an acquired image can be considered a "covered area," the number of these points defining a "coverage level," the "coverage threshold" being a minimum number of these points. Finally, the set of notable points not yet represented on an already acquired image can be considered an "area yet to be covered."

[0104] One objective of the method is to guide the user during image acquisition so that the set of acquired images contains as few images as possible, i.e., that the acquisition is efficient, but with enough images so that the coverage threshold is reached.

[0105] The first principal aspect of the invention aims to guide acquisition by means of multidimensional symbols. The second principal aspect of the invention aims to guide acquisition by informing the user of the progress of this acquisition. First main aspect of the invention

[0106] In step 1) of a method according to the first principal aspect of the invention, illustrated in [Fig.9], multidimensional symbols, i.e. two-dimensional or three-dimensional, preferably three-dimensional, are arranged, i.e. "anchored", and presented to the user, in augmented reality, in the space of the oral object, the shape and / or position of a symbol being determined so as to indicate to the user all or part of the acquisition conditions adapted for the acquisition of said image.

[0107] Of course, the user must be able to interpret a symbol. The information associated with a symbol may be explicit, for example, when it is in the shape of an arrow. In this case, no training is necessary. Otherwise, the user may be trained to provide them with the "rules of the game," that is, how they are expected to process symbols.

[0108] A two-dimensional or three-dimensional symbol that appears in augmented reality extends virtually, that is to say without having a physical existence, into the real scene observed by the acquisition device, or into an equivalent virtual scene, in particular a model of at least a part of the real scene. It extends in a plane or defines a volume, respectively.

[0109] A representation in an equivalent virtual scene advantageously makes it possible to make the symbols appear more clearly, as illustrated for example in [Fig.7].

[0110] The screen displays the preview image representing the actual scene observed by the acquisition device and / or an equivalent image, in particular a view of said model that corresponds to the observation of the actual scene by the acquisition device. It also displays the symbols as if they had a physical, real existence and were present in the actual scene.

[0111] Each symbol is / are associated with one or more acquisition conditions for a respective image, in particular - a predetermined observation axis of the target or a predetermined range of observation axes, and / or - a predetermined distance between the target and the acquisition device, or a predetermined range of such distances, and / or - a predetermined orientation of the acquisition device around its optical axis, or a predetermined range of such orientations.

[0112] The computer knows the predetermined observation conditions associated with each symbol.

[0113] The number of symbols is adapted to the number of images in the desired image set. It is preferably greater than 2, 5, 10 or 100 and / or less than 1000.

[0114] A symbol, preferably each symbol, is preferably represented on the preview image or on the equivalent image, updated in real time when the user moves the acquisition device.

[0115] A symbol, preferably each symbol, is preferably represented, in augmented reality, on a screen of the acquisition device or in communication with the acquisition device, preferably on a screen of a mobile phone used to acquire the images.

[0116] A symbol, preferably each symbol, is preferably anchored and / or conformed so that the modification of its representation on said screen resulting from a movement of the acquisition device informs the user that said movement moves away from or closer to predetermined acquisition conditions associated with said symbol.

[0117] The predetermined acquisition conditions define an observation axis of the target by the acquisition device, i.e. a predetermined observation axis, and / or a predetermined distance of the acquisition device from the target, preferably along the observation axis, and / or a predetermined orientation of the acquisition device around its optical axis, and said modification of the symbol's representation on said screen preferably informs the user that said movement - reduces or increases the difference in angle between the optical axis of the acquisition device and the predetermined observation axis, i.e., improves or degrades the angulation of the acquisition device; and / or - reduces or increases the difference between the distance between the acquisition device and the target and the predetermined distance; and / or - reduces or increases the difference between the orientation of the acquisition device around its optical axis and the predetermined orientation; preferably reduces or increases each of the three aforementioned differences.

[0118] The principles of augmented reality are well known. Determining said angle and / or said distance and / or said difference in orientation does not pose any particular difficulty to a person skilled in the art.

[0119] Preferably, a multidimensional symbol, preferably each multidimensional symbol, has a shape defining a principal direction, or "symbol axis", identifiable by the user, for example an axis of revolution, and indicating a predetermined observation axis associated with the symbol.

[0120] A multidimensional symbol, preferably each multidimensional symbol, includes, when the optical axis of the acquisition device coincides with said principal direction, a dimension which, on the representation of the symbol on the screen, is variable depending on the position of the acquisition device along the optical axis, that is to say depending on the distance between the acquisition device and said symbol.

[0121] Said dimension is evaluable by observation of the screen by the user, and the user knows a value of said dimension defining the position of the acquisition device at the predetermined distance associated with said symbol.

[0122] For example, the multidimensional symbol has the form of a superposition of rings, preferably of different diameters, - the predetermined orientation being obtained when the centers of the rings are aligned along the optical axis of the acquisition device, that is to say, when said centers appear on the screen as coincident, and / or - the predetermined distance being obtained when the centers of the rings are aligned along the optical axis and the spacing between said rings as they appear on the screen, preferably on the representation of the symbol in the preview image or the equivalent image, has a predetermined value, for example when a first ring appears adjacent to a second ring, that is to say when the inner contour of the first ring is in contact with the outer contour of the second ring.

[0123] In step 2), an image is acquired when the predetermined acquisition condition(s) associated with a symbol is / are met.

[0124] The acquisition can in particular be carried out according to a step a) as described below. The image can be of the type of images described below for step a).

[0125] The image is then analyzed to determine the acquisition conditions.

[0126] In one embodiment, each acquired image is submitted to a first neural network trained to detect the representation of the target, and / or notable points of said target, on the image, and to a second neural network trained to recognize, from the representation of the target or of said remarkable points on the image, said acquisition conditions, and in particular the angulation and / or distance of the acquisition device relative to the target.

[0127] The first neural network can be chosen in particular from among the Object Detection Networks, and in particular from among the neural networks listed below, in the passage relating to step b2). For example, the neural network is trained by presenting it with, for example, more than 1000 historical images: as input, a historical image representing a historical target and / or landmarks, and The output will show the representation of said historical target and / or notable points on the historical image.

[0128] The neural network thus learns to recognize, in a new image, the representation of the target and / or notable points.

[0129] The second neural network can be chosen in particular from among networks specialized in image classification, called "CNNs" ("Convolutional neural networks"), for example AlexNet (2012), ZF Net (2013), VGG Net (2014), GoogleNet (2015), Microsoft ResNet (2015), Caffe: BAIR Reference CaffeNet, BAIR AlexNet, Torch: VGG_CNN_S, VGG_CNN_M, VGG_CNN_M_2048, VGG_CNN_M_1024, VGG_CNN_M_128, VGG_CNN_F, VGG ILSVRC-2014 16-layer, VGG ILSVRC-2014 19-layer, Network-in-Network (Imagenet & CIFAR-10), Google: Inception (V3, V4). For example, the neural network is trained by presenting it with, for example, more 1000 historical images: as input, a historical image representing a historical target and / or landmarks, and The output consists of "historical" acquisition conditions for the historical image.

[0130] The neural network thus learns to define, for a new image, the conditions for its acquisition.

[0131] Determining the conditions for acquiring an image can also be achieved by searching for a view of a model of the user's arcade that corresponds to the image, for example with an optimization operation, preferably a metaheuristic method, preferably an evolutionary method, preferably a simulated annealing method. An example of such a search is described, for example, in PCT / EP2015 / 074859, in European patent application no. 18 184477.0 or in WO2016 / 066651.

[0132] Preferably, when the symbol is observed along the predetermined observation axis, and / or when the acquisition device is at said predetermined distance and / or when the acquisition device is oriented along said predetermined orientation, preferably when the symbol is observed along the predetermined observation axis, and when the acquisition device is at said predetermined distance, and when the acquisition device is oriented along said predetermined orientation, an image is acquired, preferably automatically, that is to say without specific intervention by the user.

[0133] Preferably, a symbol changes its appearance, for example its color, or disappears when an image has been acquired under the acquisition conditions associated with said symbol. Second main aspect of the invention

[0134] The process according to the second main aspect of the invention comprises several cycles of steps a) to c).

[0135] In step a), an image, preferably a photograph, representing the user's oral object is acquired by means of an image acquisition device. In one embodiment, a film is acquired with the image acquisition device, and the acquired image is extracted from the film.

[0136] In one embodiment, an "original mask," preferably a dot cloud, is projected onto the scene observed by the acquisition device in step a), preferably using a projector integrated into the acquisition device. The distorted mask resulting from the projection of the original mask then appears on the preview image or the equivalent image. In one embodiment, the projection is in infrared light so that the distorted mask is not visible to the naked eye. In another embodiment, the acquired image is the image representing the distorted mask. The acquisition device then preferably uses an infrared camera. However, the nature of the distorted mask is not limited.

[0137] The image is preferably acquired by the user himself. The user can acquire the image using a mobile phone.

[0138] The acquired image is preferably "extraoral", that is to say without the optical lens of the acquisition device being introduced into the user's mouth.

[0139] The image acquisition device may in particular be a mobile phone, a tablet, a camera or a computer, the image acquisition device preferably being a mobile phone or a tablet, in particular so that the user can acquire images anywhere, and in particular outside the office of a dental professional, for example more than 1 km from the office of a dental professional.

[0140] In one embodiment, the user uses a mobile phone and a holder to which the mobile phone is removably attached, the holder being held against the user during the acquisition of at least some, preferably all, of the images. In particular, the holder may be of the type described in PCT / EP2021 / 068702, EP17306361, PCT / EP2019 / 079565, PCT / EP2022 / 053847, FR2113577, FR2206750, or FR2206745.

[0141] In a preferred embodiment, the user uses a mobile phone that is free to move, that is, one whose position and orientation they can freely determine, and in particular, not attached to a support. The method according to the invention allows the user to be guided in their shooting, so that guidance by means of a support is not necessary. Preferably, the image acquisition device is not in contact with the user's mouth, either directly or via a support for the image acquisition device.

[0142] Previously, depending on the target, the computer or acquisition device may ask the user to activate or deactivate a An orthodontic appliance, such as an orthodontic splint, attachment, or archwire appliance, may be used. The user may also be asked to retract their lips away from their dental arches, preferably using a retractor, to better expose the target to the imaging device, for example, to fully expose at least one tooth, particularly the extrados of an incisor and / or at least partially the extrados of a molar. The user may also be asked to open their mouth wide to acquire occlusal images of the lingual and occlusal surfaces of the teeth and palate.

[0143] The number of images acquired during a step a) is preferably less than 100, preferably less than 50, preferably less than 10, so that the guidance information is updated quickly.

[0144] Before the implementation of the first step a) of a process according to the invention, the coverage level is zero.

[0145] At step b), the coverage level is updated to take into account the image(s) acquired in the immediately preceding step a), or "new images".

[0146] In step b), the computer therefore analyzes each new image, preferably following the following steps: bl) determination of a potential contribution by the new image; b2) determination of the intersection between the potential contribution and the prior contribution made by the previously analyzed images; b3) if the intersection is not empty, add the potential contribution to the previous contribution.

[0147] In step 1b), the computer determines the potential contribution of the new image. In particular, it determines whether the new image represents, at least partially, the target. If not, this new image cannot make a contribution, and the computer proceeds to analyze the next new image. If so, the computer determines the potential contribution of the new image, for example, by determining the outline of the target representation on the new image, or the number of the target tooth or teeth represented, at least partially, on the new image.

[0148] At step b2), the computer then compares the potential contribution to the set of contributions resulting from the analysis of the previously analyzed images, or "previous contribution".

[0149] For example, the potential contribution of the new image is the representation of the target on the new image. The computer evaluates the intersection of this potential contribution and the previous contribution consisting of the union of all the representations of the target on the previously analyzed images.

[0150] If this intersection is empty, the new image cannot make any new contribution and the computer moves on to analyzing the next new image. If this in If the intersection is not empty, meaning that the new image represents an area of ​​the target that was not on any of the previously analyzed images, the computer adds to the previous contribution a new contribution consisting of said intersection.

[0151] As another example, the potential contribution of the new image is the number of one or more teeth of the target identified in the new image. The computer evaluates the intersection of this potential contribution and the previous contribution, which consists of all the numbers of the target teeth identified in the previously analyzed images. If this intersection is empty, the new image cannot provide any additional contribution, and the computer proceeds to analyze the next new image. If this intersection is not empty, the computer adds this intersection to the previous contribution.

[0152] The determination of the potential contribution of a new image can be carried out by any known means.

[0153] In one embodiment, it comprises segmenting the new image so as to identify the possible representation, total or partial, of the target. The analysis can be performed using conventional segmentation methods.

[0154] In particular, the new image can be submitted to a neural network trained to detect the representation of the target on the new image, for example to determine the numbers of the teeth represented on the image, and / or the outlines of said teeth, and / or of the mouth and / or of the lips, and / or of the tongue, as described for example in European patent application No. 18 184477.0.

[0155] Networks specializing in the localization and detection of objects in an image are well known. The neural network can be chosen from among Object Detection Networks, for example R-CNN (2013), SSD (Single Shot MultiBox Detector: Object Detection network), Faster R-CNN (Faster Region-based Convolutional Network method: Object Detection network), Faster R-CNN (2015), SSD (2015), RCF (Richer Convolutional Features for Edge Detection) (2017), SPP-Net, 2014, OverFeat (Sermanet et al.), 2013, GoogleNet (Szegedy et al.), 2015, VGGNet (Simonyan and Zisserman), 2014, R-CNN (Girshick et al.), 2014, Fast R-CNN (Girshick et al.), 2015, ResNet (He et al.), 2016, Faster R-CNN (Ren et al.), 2016, FPN (Lin et al.), 2016, YOLO (Redmon et al.), 2016, SSD (Liu et al.), 2016, ResNet v2 (He et al.), 2016, R-FCN (Dai et al.), 2016, ResNeXt (Lin et al.), 2017, DenseNet (Huang et al.), 2017, DPN (Chen et al.), 2017, YOLO9000 (Redmon and Farhadi), 2017, Hourglass (Newell et al.), 2016, MobileNet (Howard et al.), 2017, DCN (Dai et al.), 2017, RetinaNet (Lin et al.), 2017, Mask R-CNN (He et al.), 2017, RefineDet (Zhang et al.), al.), 2018, Cascade RCNN (Cai et al.), 2018, NASNet (Zoph et al.), 2019, ComerNet (Law and Deng), 2018, FSAF (Zhu et al.), 2019, SENet (Hu et al.), 2018, ExtremeNet (Zhou et al.), 2019, NAS-FPN (Ghiasi et al.), 2019, Detnas (Chen and al.), . 2019, FCOS (Tian et al.), 2019, CenterNet (Duan et al.), 2019, EfficientNet (Tan and Le), 2019, or AlexNet (Krizhevsky et al.), 2012.

[0156] The above list is not exhaustive. For example, a neural network can be trained by presenting it with, for example, over 1000 historical images: The input is a historical image representing a historical target, and the output is the representation of said historical target on the historical image.

[0157] The neural network thus learns to recognize, in a new image, the representation of the target.

[0158] When the intersection between the potential contribution and the previous contribution involves a comparison of the representations of the target on the new image and on the previously analyzed images, these representations are preferably projected onto a common reference model in order to take into account different acquisition conditions, and in particular an orientation of the acquisition device which varies depending on the image considered.

[0159] The reference model preferably represents a reference oral object, preferably similar to, or even identical to, the user's oral object.

[0160] To project an image, the computer analyzes the image to determine the conditions of its acquisition, that is to say the actual acquisition conditions. In particular, it evaluates the distance between the acquisition device and the user's oral object and the orientation of the acquisition device in space, relative to the user's oral object, at the time of image acquisition.

[0161] The determination of the actual acquisition conditions can be carried out as described for example in European patent application no. 18 184477.0 or in WO2016 / 066651, or by submitting the image to a neural network trained to determine the acquisition conditions of the image submitted to it.

[0162] The actual acquisition conditions are then reproduced virtually with respect to the reference model, and the representation of the user's target on the image is projected onto the reference model.

[0163] The set of projected surfaces obtained from the previous images can constitute the previous contribution. The projected surface obtained from the new image is the potential contribution.

[0164] Preferably, each image is submitted to a first detection neural network, identifying oral objects represented in the image, in particular, the tongue and / or tooth numbers, and / or the gums and / or the mouth and / or the lips and / or notable points of these organs, then each image is submitted to a second neural network trained to determine the acquisition conditions of the image submitted to it. Preferably, the second neural network takes as input the oral objects detected by the first neural network, which improves the determination of acquisition conditions.

[0165] In one embodiment, the determination of the potential contribution of a new image is determined by comparing the image to a "reference" image, for example a photograph or panoramic shot, preferably of at least one dental arch similar or identical to the user's dental arch.

[0166] The target is then generally not represented in the same way in the reference image and in the new image. Preferably, a neural network is trained so that it learns to establish a correspondence between the objects represented in the two images.

[0167] For example, it is trained by presenting it with: The input consists of historical records, each containing a historical image representing a historical target under possible acquisition conditions with the acquisition device, and an identification of the representation of the historical target in the historical image, and The output is the identification of said historical target on a historical reference image.

[0168] The neural network thus learns to recognize, in a reference image, the representation of the target that corresponds to the representation of the target in a new image presented to it. The neural network thus learns to identify the potential contribution of the new image.

[0169] The process can be implemented several times, each time with a new reference image.

[0170] At step b3), the computer adds the potential contribution to the previous contribution if the intersection is not empty and calculates the coverage level resulting from the increment of the previous contribution by the new contribution.

[0171] In a preferred embodiment, the computer evaluates the quality of the acquired image(s) and only adds the potential contribution to step b3) if the quality exceeds a predefined quality threshold. Quality may, in particular, be an assessment of the image's sharpness and / or contrast, and / or color balance, and / or the distance between the acquisition device and the user's mouth. Advantageously, only images of satisfactory quality are considered.

[0172] In one embodiment, the image acquisition device, preferably in the form of a mobile phone, is attached to a support that is kept in contact with the user during acquisition, as described previously, for example, a support of the type described in PCT / EP2021 / 068702, EP17306361, PCT / EP2019 / 079565, PCT / EP2022 / 053847, FR2113577, FR2206750, or FR2206745. With such a support, the image quality (in particular brightness, distance from the acquisition device relative to the target, the angulation of the acquisition device relative to the target and the orientation of the acquisition device around its optical axis) is advantageously well controlled so that the evaluation of the quality of the image or images acquired is optional.

[0173] Preferably, the support is not bitten by the user, and, preferably still, allows opening and closing (to a position in which the arches are in contact with each other in the occlusal plane) of the arches.

[0174] Quality assessment is particularly advantageous in the absence of such support.

[0175] Depending on the result, the computer can decide to take several images, for example to vary the focal length in order to acquire a first clear image of the group of incisors, then a second clear image of the posterior group of teeth.

[0176] The acquisition of several images with different calibration conditions can be based on quality assessment, but can also be programmed to be systematic at each acquisition stage.

[0177] In step c), the computer compares the coverage level to the coverage threshold. If the coverage level is greater than or equal to the coverage threshold, step c) is completed. Otherwise, the computer determines guidance information to direct the user to position the image acquisition device towards "future" acquisition conditions suitable for acquiring, in the next step a), an additional image increasing said coverage level.

[0178] The guidance information is thus determined to inform the user about the areas of the target for which he or she still needs to acquire one or more image(s). It is presented to the user and guides him or her so that he or she can orient and / or position the image acquisition device according to the future acquisition conditions to be adopted for the next step a).

[0179] In a preferred embodiment, the computer determines, for example by random search or with an optimization algorithm, the future acquisition conditions for the next cycle, so that the acquisition of images under these future acquisition conditions maximizes the increase in the coverage level.

[0180] The presentation of guidance information may include visual, auditory and / or haptic transmission, in particular tactile, of guidance information.

[0181] For example, the guidance information may include audio instructions directing the user to move the imaging device closer to or further from their teeth, to shift the imaging device to the right or left, to rotate the imaging device around the dental arch, to open or close their mouth, or to open or close their jaw.

[0182] Tactile transmission of guidance information can be a vibration for example, instructing the user to stop a movement.

[0183] A haptic transmission of guidance information can be a vibration, for example to indicate the successful passage of a target crosshair over a surface of the target or over a symbol.

[0184] The presentation of guidance information can be adapted to the user.

[0185] Preferably, the presentation of guidance information includes several different types of transmissions stimulating several different senses, thus facilitating communication to the user.

[0186] Preferably, the guidance information is displayed on a screen, preferably on a screen of the image acquisition device. The display of the guidance information on a screen may include - preferably a reference frame allowing the user to orient themselves when moving the acquisition device in space, that is to say, to assess how the acquisition device is positioned relative to the oral object, and in particular relative to the target, and - an indicator showing movement relative to this reference frame.

[0187] The reference frame preferably represents, at least partially, in a symbolic or realistic manner (i.e., adapted so that the user recognizes the object represented), at least one oral object as observed by the acquisition device. It is determined according to the actual acquisition conditions of the acquisition device.

[0188] The reference image can be, for example, a preview image, i.e. the image observed by the acquisition device, preferably the mobile phone, in real time and displayed on the screen of the acquisition device and / or an equivalent image representing a part of the user, for example the user's head or part of the head or the mouth or the user's dental arches (by "equivalent" we mean that the image corresponds to an observation of the part of the patient that can be superimposed with the image observed by the acquisition device, and in particular observed along the optical axis of the acquisition device). The equivalent image can be a line drawing, for example representing the outline of a part of the user.

[0189] The reference frame may represent a view of a user-specific model or a generic model, said model thus representing, precisely or more crudely, a part of the user, preferably at least the target, preferably at least the oral object.

[0190] A generic model is common to several individuals. A generic reference frame can be determined, in particular, by statistical analysis of historical data representative of these individuals. A generic model can, for example, be a model of a typodont.

[0191] A user-specific model may be a model of all or part of the user's oral object, in particular the user's target. It may, in particular, be a scan of the user's dental arches. It may also include or be a 3D model of a user's arch in a configuration specific to a treatment stage. In particular, it may include or be a 3D model of a user's arch in a configuration specific to a stage of treatment with orthodontic aligners, and in particular a 3D model used for the design and fabrication of an orthodontic aligner. Such a 3D model may be generated at the beginning of orthodontic treatment or during orthodontic treatment.

[0192] The equivalent image is preferably a view of a generic or specific model. Preferably, a texture is applied to the model to make it more realistic and allow the user to identify more easily with the model. The texture can be extracted from an image, for example from an image acquired in step a), and then applied to a model, preferably chosen from a database before the first step a).

[0193] The model of which a view is used as a reference can in particular be the reference model used as a projection support for the acquired images, described above.

[0194] The equivalent image may be at least partly symbolic. It may include, for example, a set of geometric shapes representing the oral object, for example a set of discs, each disc representing a tooth of a part of a dental arch, the oral object being the dental arch.

[0195] Figure 10 shows two examples of equivalent images, representing the view of a 3D model of a user's dental arch, with and without gum tissue respectively. The view could also be, for example, a wireframe representation.

[0196] In particular, when the equivalent image is a view of a generic or specific model, the image acquisition device can display the preview image, preferably in a mini window, or "thumbnail", which facilitates spatial referencing for the user.

[0197] Displaying the reference frame on the screen is optional if the indicator provides an indication of the desired movement. For example, the indicator could be an arrow or a message suggesting a particular movement. However, displaying the reference frame on the screen is preferred because it greatly facilitates precise positioning of the acquisition device.

[0198] The indicator is displayed, preferably with the reference frame, on the screen, preferably on the screen of the image acquisition device, preferably on a mobile phone or tablet screen.

[0199] In a preferred embodiment, the reference frame includes a representation of The oral object and the indicator is a mark indicating an area of ​​this representation that is not yet covered. The indicator may be, for example, a particular outline surrounding this area or, preferably, a particular color applied to this area, or a symbol superimposed on this area. By "particular" outline or color, we mean an outline or color that allows the user to distinguish this area from the rest of the oral object representation.

[0200] This display allows the user to be guided quickly and efficiently. This guidance, which gives the user a great deal of freedom, is intuitive, so the user does not need to have received prior training to be guided.

[0201] The indicator can in particular be displayed in transparency or highlighted on the representation of the oral object.

[0202] The indicator is preferably displayed in augmented reality when the reference is a preview image or an equivalent image. Coverage rates and thresholds

[0203] Preferably, in step c), the user is informed, preferably in real time, about the level of coverage achieved, i.e. about the progress of the acquisition, and preferably about the coverage threshold.

[0204] Preferably, the information on the coverage level and / or the information on the coverage threshold is / are presented on a screen, preferably on the screen of the user's mobile phone. The information may, for example, take the form of a counter or a gauge, for example in the form of a progress bar.

[0205] In a preferred embodiment, the coverage level and / or coverage threshold is / are represented "graphically" on the screen, in particular in the form of line(s) and / or surface(s) and / or symbols.

[0206] In one embodiment, the following are displayed on the screen in such a way that they can be distinguished: - the initial surface area to be covered, - the covered area, and - preferably, a representation of elements of the target context, for example parts of the oral object different from the target, i.e. parts of the oral object which the process is not intended to cover, for example teeth adjacent to the teeth for which we wish to acquire images.

[0207] For example, when the reference frame is a symbolic or, preferably, realistic representation of the oral object or target, the initial area to be covered can be displayed on the screen in a way that is identifiable to the user in order to inform them of the coverage threshold. In particular, it can be colored a specific color, or more generally represented with a specific appearance, or delimited by a specific outline. The area thus represented with a specific appearance or encircled by this outline represents the coverage threshold.

[0208] Similarly, the covered area, that is, the area for which at least one image has already been acquired, can be displayed on the screen in a way that is identifiable to the user in order to inform them of the level of coverage. In particular, it can be colored a specific color, or more generally represented with a specific appearance, or delimited by a specific outline. The area(s) thus represented with a specific appearance or enclosed by this outline represent(s) the level of coverage.

[0209] For example, a target area can be displayed in green or red depending on whether that area has been acquired or remains to be acquired. The covered area can be displayed transparently or highlighted.

[0210] In one embodiment, the coverage threshold is graphically represented as a set of symbols displayed near, preferably superimposed on, the representations of a set of respective teeth. The representations of these teeth belong to, or even constitute a reference frame. For example, the symbols can be presented in augmented reality on the mobile phone's preview image or on a view of a dental arch model, preferably on a view of a model of the user's dental arches. The appearance of the symbols relating to teeth for which the desired images have already been acquired ("covered teeth") can be different from that of the symbols relating to teeth for which all the desired images have not yet been acquired ("teeth yet to be covered"), thus allowing the coverage rate to be graphically visualized.

[0211] In one embodiment, the symbol relating to a tooth disappears as soon as the tooth is covered. The user then sees the difference between the coverage threshold (all symbols initially displayed) and the coverage level (symbols that have disappeared).

[0212] The "graphical" display of the coverage threshold and coverage level is particularly effective in enabling the user to acquire all the required images.

[0213] Remarkably, the graphical representations of the coverage threshold and coverage level allow visualization of the areas of the target that remain to be covered, i.e., those for which desired images still need to be acquired. These graphical representations can thus be used as an indicator to guide the user. For example, coloring the covered area with a different color than the area still to be covered highlights the remaining area and thus guides the user.

[0214] The graphic, or “visual”, marking of the initial surface to be covered, the covered surface or the surface still to be covered is not limited to the application of a colour or texture or outline or to the representation of particular symbols.

[0215] Preferably, the graphical representations of the coverage threshold and the coverage level are displayed in augmented reality, preferably on the mobile phone screen.

[0216] In one embodiment, a timer is activated to measure the duration of image acquisition since the first step a). Displaying this duration and the coverage level and / or the difference between the coverage threshold and the coverage level is a motivating factor for the user.

[0217] In one embodiment, a score is calculated based on the time taken to reach the coverage threshold and / or the quality of the images acquired, and / or the usefulness of the images acquired, more generally on an objective set for the user.

[0218] In one embodiment, the initial area to be covered comprises zones assigned a utility coefficient, and the score is determined based on the utility coefficients of the zones within the covered area. For example, in one embodiment, the initial area to be covered may consist of a portion that must be covered and a portion that is optional. The utility coefficient assigned to a pixel in the "must" portion may be, for example, 100, and the utility coefficient assigned to a pixel in the "optional" portion may be, for example, 10. The score may, for example, be a function of, or even the sum of, the utility coefficients for all pixels in the covered area.

[0219] The score can be compared with scores previously obtained by the user or by other users, in order to obtain a ranking of the image set acquisition operation.

[0220] A ranking can be established for several patients, for example for all the patients of the same practitioner. An informational message and / or a gift, for example a reward, can be sent to a patient according to their ranking order.

[0221] The stopwatch and / or score and / or ranking may be displayed on the screen of the acquisition device.

[0222] Acquisition thus becomes playful. In particular, acquisition can be presented as a video game, the objective being to reach the coverage threshold as quickly as possible.

[0223] Guided by the guidance information and motivated by the information on the coverage level, the user modifies the acquisition conditions, which allows a new step a) to be started, preferably immediately at the end of step c).

[0224] When the coverage level is presented to the user, they can advantageously visualize immediately the effect of moving the acquisition device, in particular when the target changes color or when symbols associated with teeth change appearance or disappear as the coverage progresses. image acquisition. The guidance is advantageously intuitive.

[0225] In a preferred embodiment, the screen displays at all times a realistic representation of the oral object and the surface area covered at that time. The surface area covered is completed as the cycles progress, allowing the user to easily identify the remaining surface area to be acquired and to position and orient the image acquisition device accordingly.

[0226] The time interval between two successive cycles of steps a) to c) is preferably less than 5 minutes, 1 minute, 30 seconds, or 1 second. Preferably, the user acquires the images in real time, preferably by filming the oral object, with steps b) to c) being performed immediately for each acquired image.

[0227] At the end of the step cycles a) to c), i.e. when the coverage level is greater than or equal to the coverage threshold, the acquired images can be transmitted to the user and / or preferably to a dental care professional.

[0228] The acquired images can be stored, for example in a database, preferably accessible to a dental professional and / or the user. For example, the acquired images can be stored in the user's medical record.

[0229] The set of acquired images typically comprises more than 2, more than 5, more than 10, more than 50, more than 100 and / or less than 10,000 images.

[0230] Said set of acquired images may be used, in particular for: - to assess the user's dental situation before, during, or after orthodontic or dental treatment; and / or - generate or correct a model of the user's dental arch; and / or - design an orthodontic appliance; and / or - to design and offer dental treatment, for example hygiene monitoring, periodontal monitoring, or whitening.

[0231] In a particular embodiment, at the end of the cycles of steps a) to c), the method may include analyzing the acquired images to generate a model of the target, called the "final model." The final model may be transmitted to the user, preferably a dental professional. The final model may represent the target with high accuracy. The final model may be generated by a computer belonging to the dental professional to whom the acquired images are transmitted, or generated by the image acquisition device. The final model may be stored, for example, in a database, preferably accessible to a dental professional and / or the user. For example, the final model may be stored in the user's medical record. Examples

[0232] The objective of the acquisition is to acquire a set of images of a target consisting, for example, of all the user's teeth. The dental arches, which constitute the oral object, include said teeth and the gingiva. The oral object is modeled as a reference model 16 accessible to the computer. The reference model 16 can be derived from a database and can be generic. The target is identified on the reference model. The initial area to be covered is therefore the area of ​​the target in the reference model.

[0233] Figures 3, 5, 6 and 7 illustrate examples of implementation of the first principal aspect of the invention, in which multidimensional symbols 24 are virtually arranged in space to guide the user to associated acquisition conditions.

[0234] In the example in [Fig. 3], the symbols 24 are two-dimensional. Each has the form of three concentric and coplanar rings. They are shown on a view of a reference model representing dental arches, said view observing the model as the acquisition device observes the user's dental arches. The view is preferably displayed on the screen of a phone used for acquisition. The user aims to position the phone so as to view a target head-on, i.e., so that the rings appear circular. The optical axis then coincides with a predetermined observation axis suitable for image acquisition.

[0235] No target is necessary for this guidance. However, a target representing, for example, the circular contours of the rings when viewed from the front would improve the accuracy of the positioning of the acquisition device.

[0236] In the example in [Fig. 5], the symbols are three-dimensional. Each has the form of three concentric, overlapping rings. They are shown on a view of a reference model representing dental arches, this view observing the model as the acquisition device observes the user's dental arches. The view is preferably displayed on the screen of a phone used for acquisition. The user aims to position the phone so as to view a target head-on, that is, so that the rings appear circular and concentric, as in [Fig. 6]. The optical axis then coincides with a predetermined observation axis, namely the X-axis of the rings, suitable for image acquisition.

[0237] In the example of [Fig. 7], each symbol 24 consists of two concentric hoops extending in planes at 90° to each other. The two hoops are preferably of the same shape (same inner and outer diameters), and preferably enclosed within a colored sphere 26, but transparent to facilitate their localization. The intersection of the two planes defines a predetermined observation axis X associated with the symbol, identifiable by the user. This symbol form allows for very easily determine how to move the acquisition device.

[0238] In the embodiment of [Fig.7], the first horizontal hoop determines whether the acquisition device should be moved up or down, and the second vertical hoop, in a plane passing through the center of the mouth, determines whether the acquisition device should be moved to the right or to the left.

[0239] Guidance with a three-dimensional symbol is particularly effective. No target is necessary to obtain precise positioning of the optical axis of the acquisition device along the predetermined observation axis adapted for image acquisition.

[0240] A three-dimensional symbol also allows guidance to a predetermined distance along the predetermined observation axis. In the example in [Fig. 8], the distance d between the rings represents the distance between the acquisition device and the symbol along the symbol's X-axis, i.e., along the predetermined observation axis. The predetermined distance can, for example, correspond to a view of the symbol in which the rings touch (d = 0). It is easy for the user to move the acquisition device to this position.

[0241] When the predetermined acquisition conditions associated with a symbol are met, an image is acquired, preferably automatically, and preferably the appearance, for example the color, of the symbol is modified, or the symbol disappears.

[0242] An example illustrating the second main aspect of the invention is now described:

[0243] In step a), an image is acquired using the acquisition device.

[0244] In step b), the acquired image is analyzed to update the coverage level.

[0245] In particular, we are looking for the possible representation of the target on the acquired image, that is to say the existence of a potential contribution of the acquired image.

[0246] If this potential contribution exists, the view of the reference model that exhibits maximum concordance with the acquired image is sought, and the area of ​​said view corresponding to the target is deduced, and consequently the corresponding area on the reference model. If a portion of this latter area has not yet been recorded as belonging to the covered area, it is added to the covered area and marked on the reference model, preferably colored with a first color specific to the covered area, for example, green, the remainder of the target area on said view preferably being a second color, for example, red, and the area of ​​the reference model not defining the target preferably being a third different color, for example, white.

[0247] The view of the reference model 16 equivalent to the preview image is projected onto the screen of the image acquisition device 10, preferably a mobile phone, along the direction of the optical axis.

[0248] The view of the reference model thus projected can - be superimposed almost exactly with the preview image displayed on the screen, whether transparent or not, or - replace the preview image, as in [Fig.4].

[0249] It allows the user to visualize the areas covered and yet to be acquired, thanks to their specific colors.

[0250] This presentation allows the user to quickly and easily identify the remaining tooth areas to be covered and to easily orient the acquisition device accordingly. It also informs the user of the level of coverage.

[0251] As images are acquired during the cycles of steps a) to c), the covered area increases.

[0252] The images in [Fig. 4] each represent a view of a reference model depicting two dental arches, preferably similar to those of the user. Each view corresponds to a preview image and is displayed in place of said preview image, preferably on the screen of a mobile phone used for image acquisition. The views of the reference model are therefore "equivalent" to preview images. In other words, when the user rotates the acquisition device around their mouth, the displayed view of the reference model immediately adjusts accordingly. The user thus easily associates the reference model with their dental arches. They can therefore easily position and orient the acquisition device to acquire images of the uncovered teeth.

[0253] In the embodiment of [Fig. 4], the target consists of all the teeth of both arches, and the oral object consists of these two arches (and therefore includes, in addition to the teeth, the gums). The color of a tooth is specifically dark gray (GF) when the tooth coverage is sufficient, and light gray (GS) otherwise.

[0254] As the user moves the acquisition device in front of their teeth, the covered area increases, and therefore the number of teeth sufficiently covered, in dark grey, increases. The other teeth remain in light grey.

[0255] The coverage level corresponds, for example, to the percentage of the surface area covered relative to the initial surface area to be covered. The coverage threshold can be a percentage of the target surface area to be covered. For example, the threshold can be 90%, meaning that when more than 90% of the tooth surface area is covered, the coverage threshold is reached.

[0256] Symbols, possibly one-dimensional, i.e., in the form of a point, can symbolically represent the teeth to be covered (target). When, for example, at least 90% of the surface of a tooth is acquired, better when at least 95% of the When the surface of a tooth is covered, or even better, when the entire surface of a tooth is covered, the symbol representing that tooth is no longer displayed on the screen. Alternatively, the symbol is displayed in color or highlighted.

[0257] As is now clear, a device and a method according to the invention advantageously increase user autonomy and improve the quality and content of images acquired by a user with no particular knowledge in the dental field. They also allow for the remote creation of a 3D model of a target belonging to or constituting an oral object of the user. Finally, they greatly facilitate the remote determination of orthodontic treatment, as well as the monitoring of any orthodontic treatment, without the user needing to make an appointment with a dental professional.

[0258] Of course, the invention is not limited to the embodiments described and represented above.

[0259] In particular, the mobile phone can be replaced by a device comprising a holder equipped with a camera and held in contact with the user during the acquisition of the image set, and a screen displaying the scene observed by the camera, said screen being integrated into the holder or at a distance from the holder.

[0260] The shape of the symbols is not limiting. 1, 2 or 3 dimension symbols can be presented simultaneously in augmented reality.

Claims

Demands

1. A method for acquiring a set of images covering a target belonging to a user's oral object, the method comprising the following steps: 1) presenting to the user, on a screen (12) and in augmented reality in the space of the oral object observed by an image acquisition device (10), a multidimensional symbol or a set of multidimensional symbols (24), the shape and / or position of each symbol being determined so as to indicate to the user at least one predetermined acquisition condition suitable for acquiring said image; 2) for each symbol, acquiring, with the acquisition device, said image when said at least one predetermined acquisition condition associated with said symbol is met, preferably when all the predetermined acquisition conditions associated with said symbol are met.

2. A method according to the immediately preceding claim, wherein, in step 2), an image is acquired with the acquisition device only if a predetermined acquisition condition associated with at least one symbol is met.

3. A method according to any one of the preceding claims, wherein at least one symbol (24) defines - a symbol axis (X), preferably an axis of revolution, said acquisition condition being an angular deviation between the optical axis of the acquisition device and said symbol axis of less than 20°, and / or - a dimension (d) which, on the representation of the symbol on the screen, is variable as a function of the distance, between the acquisition device and said symbol in augmented reality, said acquisition condition being a specific value for said dimension or the membership of said dimension in a specific range of predetermined values.

4. A method according to any one of the preceding claims, wherein, in step 2), an image is automatically acquired with the acquisition device if predetermined acquisition conditions defining a position in space and / or an orientation of the acquisition device around its optical axis and including said at least one acquisition condition indicated by the symbol, are met.

5. A method according to any one of the preceding claims, wherein, in step 2), if an image is acquired with the acquisition device, - the appearance of said symbol is modified or said symbol is made to disappear, and / or - a sound signal is emitted, and / or - a score displayed on the screen is modified and relating to a coverage rate of the target by the images already acquired and / or relating to the time for the acquisition of the images already acquired and / or relating to the quality of the images already acquired and / or relating to the usefulness of the images already acquired.

6. A method according to the immediately preceding claim, wherein, when the set of images has been acquired, the user is presented, on the screen, with a ranking determined according to said score.

7. A method according to any one of the preceding claims, wherein the screen displays the symbols on preview images representing the actual scene observed by the acquisition device or on views of a model representing, like said preview images, at least said oral object or said target.

8. A method according to any one of the preceding claims, wherein the screen displays a target in a fixed position on the screen, said symbol preferably having a form complementary to the target when a predetermined acquisition condition associated with said symbol is met.

9. A method according to any one of the preceding claims, wherein the target comprises more than 5 teeth and / or an orthodontic appliance, and / or the symbol set comprises more than 2 symbols.

10. A method according to any one of the preceding claims, wherein the acquisition device is manipulated by the user in steps 1) and 2).

11. An acquisition method according to any one of the preceding claims, wherein the images are photographs, preferably realistic, and / or represent a distorted mask, resulting from the projection, preferably by the acquisition device, of an original mask, preferably in the form of a grid or a set of dots.

12. A device for carrying out a method according to any one of the preceding claims, comprising - an image acquisition apparatus, preferably in the form of a mobile phone (10); - a computer (14), preferably integrated into the acquisition device or in communication with the acquisition device, comprising a computer program including program code instructions for - in step 1), arrange and present to the user one or more multidimensional symbols (24) on a screen (12,18), preferably on the screen (12) of the acquisition device, in augmented reality in the space of the oral object, the shape and / or position of a symbol (24) being determined so as to indicate to the user at least one predetermined acquisition condition suitable for the acquisition of said image; - preferably, in step 2), only allow the acquisition, with the acquisition device, of said image if said at least one predetermined acquisition condition associated with a symbol is met, and / or command the acquisition device to acquire said image only if said at least one predetermined acquisition condition is met, and / or update a level of target coverage by the acquired images, and preferably compare the coverage level with a coverage threshold, and preferably display on the screen information on the coverage level and / or on the difference between the coverage threshold and the coverage level.

13. Device according to the immediately preceding claim, wherein the acquisition apparatus is - a mobile phone and said screen is integrated into the mobile phone or - a device comprising a support equipped with a camera and held in contact with the user during the acquisition of the set of images, the screen being integrated into the support or at a distance from the support.

Images