3D Scanner System With Dynamic Calibration

Abstract

The present disclosure relates to a 3D scanner system comprising an intraoral scanner comprising a housing and a transparent window in a distal end of the housing, where the transparent window comprises a fiducial marker pattern arranged in a predefined arrangement. The intraoral scanner further comprises: two or more scanning units located in the housing, each scanning unit comprising one or more camera units configured to acquire a set of images, where at least a portion of the fiducial marker pattern is imaged by the camera unit (s); and one or more processors configured to: compare the imaged fiducial marker pattern to a predefined arrangement, whereby a difference can be determined; determining whether a geometrical relationship between the scanning unit and / or the camera unit has changed based on the difference; and correcting a geometric relationship in a geometric model of the intraoral scanner based on the difference, thereby calibrating the scanner.

Description

Technical Field

[0001] This disclosure relates to a 3D scanner system including an intraoral scanner. More specifically, this disclosure relates to a system and method for recalibrating an intraoral scanner. Background Technology

[0002] 3D intraoral scanners are widely used in dentistry to create digital dental impressions. This technology enables dentists to obtain detailed and accurate representations of teeth in digital format, which can then be used for a variety of applications, including the design and fabrication of dental restorations, orthodontic appliances, and other dental prostheses.

[0003] A significant challenge associated with intraoral scanning technology is the need for accurate calibration. Calibration ensures that intraoral scanners produce reliable and consistent measurements that are crucial for accurate digital impressions, diagnosis, treatment planning, and fabrication of dental restorations. Intraoral scanners are often calibrated in the factory and sometimes rely on subsequent recalibration. Existing calibration methods typically rely on manual adjustments and are time-consuming, labor-intensive, and prone to human error.

[0004] Typically, scanner recalibration is designed to account for variations on timescales of hours or even days. However, a system and method are needed that can account for variations occurring on shorter timescales, such as those occurring during a single scan. Such a system should be able to provide accurate measurements, thereby enhancing the overall reliability and usability of intraoral scanning techniques in dental practice. Summary of the Invention

[0005] Typically, intraoral scanners require calibration at least once, for example, at the manufacturing facility. However, a challenge with intraoral scanners is that this calibration does not always provide an accurate calibration of the scanner corresponding to its intended use. Intraoral scanners are usually equipped with multiple optical and electronic components that generate heat during use. An associated problem is that these components may change their relative geometry, for example, due to thermal drift. If the true geometry deviates from a predefined relationship, such as that defined in the scanner's geometric model during calibration, the 3D scan generated by the scanner becomes inaccurate, and the scanner requires recalibration.

[0006] Currently disclosed 3D scanners address these challenges by providing a dynamically calibrated 3D scanner system, enabling intraoral scanners to be calibrated during use. This is achieved using a reference marker pattern placed in an optically transparent window of the scanner through which light is projected during use. The reference marker pattern is placed at a predefined position within the optical window. Therefore, the exact position of the reference marker is known a priori. If the position of the marker shifts or becomes distorted in the image acquired by the scanner during use, for example due to thermal drift of one or more components of the scanner, the 3D scanner system can detect this shift or new position of the marker. It is also possible that the reference marker pattern deforms, i.e., causing a change in the shape of the marker and / or a change in the spacing between the markers.

[0007] The 3D scanner system is preferably configured to detect any of these variations in the reference marking pattern to facilitate dynamic calibration of the intraoral scanner. This has the advantage of improving the scanner's accuracy, thereby generating a more accurate 3D model of the scanned object. In particular, when the scanner comprises two or more scanning units, it is important to know the geometric relationships between the scanning units so that the 3D scan data obtained from these units can be accurately stitched together.

[0008] Therefore, this disclosure addresses the above challenges by providing a 3D scanner system comprising: - Intraoral scanner, including: - A housing having a distal end for insertion into the oral cavity; - A transparent window located at the distal end of the housing, wherein the transparent window includes a reference mark pattern arranged in a predefined arrangement; The intraoral scanner further includes one or more scanning units, such as two or more scanning units, located within the housing, each scanning unit comprising: - One or more camera units, the one or more camera units being configured to acquire a set of images including at least one image from each camera unit, wherein at least a portion of the reference marker pattern is imaged by the one or more camera units; - One or more processors, said one or more processors being configured to: - By comparing the imaged reference mark pattern with the predefined arrangement, differences can be determined; - Based on the differences, determine whether the geometric relationship between the scanning unit and / or the camera unit has changed; and - The geometric relationships in the geometric model of the intraoral scanner are corrected based on the differences, thereby calibrating the scanner.

[0009] This disclosure further relates to a method for calibrating an intraoral scanner, the method comprising the following steps: - Acquire two or more sets of images, wherein the sets of images are acquired by individual scanning units of an intraoral scanner, each scanning unit including one or more camera units, wherein each set of images has a reference marker pattern. - Determine the difference between the reference mark pattern of the imaging and the predefined arrangement of the reference marks; - Based on the identified differences, determine whether the geometric relationship between the scanning unit and / or camera unit has changed; and - The geometric relationships in the geometric model of the intraoral scanner are corrected based on the identified differences, thereby calibrating the scanner.

[0010] Any specific implementation of the methods disclosed herein can be performed wholly or partially by the 3D scanner system disclosed herein. The methods can be implemented as computer-implemented methods. Therefore, this disclosure further relates to a data processing system, such as a 3D scanner system, including one or more processors configured to perform the steps of the disclosed methods for calibrating an intraoral scanner. This disclosure further relates to a computer program product including instructions that, when executed by a computer, cause the computer to perform the steps of the disclosed recalibration methods. The computer may be part of the 3D scanner system. This disclosure further relates to a computer-readable data carrier on which the computer program product is stored.

[0011] Therefore, the currently disclosed systems and methods enable dynamic calibration of intraoral scanners, thereby generating more accurate 3D models of the scanned objects. Attached Figure Description

[0012] Figure 1 An embodiment of an intraoral scanner according to the present disclosure is shown.

[0013] Figure 2 An exploded view of some components of an intraoral scanner according to an embodiment of the present disclosure is shown.

[0014] Figure 3 Another embodiment of an intraoral scanner according to the present disclosure is shown.

[0015] Figure 4 Another embodiment of an intraoral scanner according to the present disclosure is shown, wherein the scanner housing includes a removable portion.

[0016] Figure 5 Another embodiment of an intraoral scanner according to the present disclosure is shown.

[0017] Figure 6 An embodiment of the scanning unit according to this disclosure is shown.

[0018] Figure 7 An embodiment of a 3D scanner system according to the present disclosure is shown.

[0019] Figure 8 Another embodiment of the 3D scanner system according to this disclosure is shown.

[0020] Figure 9 An embodiment of the pattern to be projected and the reference mark pattern is shown.

[0021] Figure 10 An embodiment of a transparent window for an intraoral scanner as disclosed herein is shown.

[0022] Figure 11 Another embodiment of a transparent window of an intraoral scanner as disclosed herein is shown, in which a projected pattern is shown. Detailed Implementation

[0023] Scanner The scanner disclosed herein can be an intraoral scanner for acquiring images of the inside of a subject's mouth. The scanner can be a handheld scanner, i.e., a device configured for being held and operated by a person. The scanner can employ any suitable scanning principle, such as triangulation-based scanning, stereo vision, motion structure, confocal scanning, or other scanning principles. In a preferred embodiment, the scanner employs a triangulation-based scanning principle.

[0024] Scanning unit A scanner may include one or more scanning units, such as two or more scanning units. A scanning unit can be understood as a unit or device, including at least one projector unit and one or more camera units. In some embodiments, each scanning unit includes at least two camera units having at least partially overlapping fields of view along different camera optical axes. Preferably, each scanning unit includes at least four camera units having at least partially overlapping fields of view along different camera optical axes. The advantage of overlapping fields of view with camera units is that the triangulation of 3D points is improved, and therefore the accuracy of the generated 3D representation is increased.

[0025] In a preferred embodiment, the scanner employs a triangulation-based scanning principle. As an example, the scanner may include a projector unit and one or more camera units for determining points in 3D space based on triangulation. As another example, the scanner includes a projector unit and two or more camera units, wherein the camera units are configured to image the scanned object from separate views, i.e., from different directions. Specifically, the camera units may be configured to acquire a set of images, within which a correspondence problem is resolved based on triangulation. Images within this set of images may be acquired by individual camera units of the scanner.

[0026] A camera unit can be understood herein as a device for capturing images of an object. Each camera unit may include an image sensor for generating an image based on received light recorded on the image sensor. One or more image sensors may include a pixel array, wherein each pixel is associated with a corresponding camera ray. The pixel array may be a two-dimensional (2D) array. Each pixel may be covered by a microlens. In some embodiments, the image region, i.e., the 2D pixel array, is rectangular or square. Each camera unit may further include one or more focusing lenses for focusing light onto the image sensor of the given camera unit. In some embodiments, each camera unit includes two or more lenses or lens elements assembled in a camera lens stack. Thus, each camera unit may include a camera lens stack comprising a plurality of lens elements. The purpose of one or more focusing lenses or camera lens stacks may be to define or ensure a predetermined focal length or working distance of the camera unit.

[0027] The images within the set of images are preferably acquired simultaneously by the camera unit, i.e., acquired at the same time, with each camera contributing at least one image to the set of images. The images within the set of images preferably capture substantially the same area of ​​the dental object. These images may include multiple image features corresponding to pattern features in a light pattern projected onto the surface of the dental object. The correspondence problem can generally refer to the problem of determining which parts or image features of one image correspond to which parts of another image within the set of images. Specifically, in this context, the correspondence problem can refer to the task of associating each image feature with a projector ray emitted from the projector unit. In other words, the problem can also be formulated as the task of associating points in an image with points in the projector plane of the projector unit. Systems and methods for solving the correspondence problem are further described by the same applicant in PCT / EP2022 / 086763 and PA 2023 70115, the full text of which is incorporated herein by reference.

[0028] A scanner may include one or more scanning units, each of which includes a projector unit and one or more camera units. As an example, a scanner may include one scanning unit comprising a projector unit and at least two camera units. As another example, a scanner may include one scanning unit comprising a projector unit and four camera units. In yet another example, a scanner may include at least two scanning units, each comprising a projector unit and two or more camera units. In yet another example, a scanner may include at least two scanning units, each comprising a projector unit and four camera units. The projector unit and camera unit of each scanning unit can be provided as modular units for insertion into a fixed unit within the scanning unit. This has the advantage of providing a simpler and more intuitive method of assembling the scanning units. It further has the advantage of securing the projector unit and camera units(s) in a rigid structure such that the geometric relationship between the units is ideally secured and maintained. In some embodiments, the scanner has a minimum size of 18 × 18 mm at a given working distance, such as a working distance between 15 mm and 50 mm. 2 The field of view, for example, at least 20 × 20 mm 2 The field of view.

[0029] In some embodiments, the scanner includes two or more scanning units, such that the scanner's field of view can be expanded or magnified. Figure 1 An example of such an embodiment is shown, illustrating a scanner comprising two scanning units placed in series at the distal end of the scanner. In this embodiment, each scanning unit is arranged in combination with a mirror to redirect projected light toward an object, such as a person's dental arch. Scanners with extended field of view are further described by the same applicant in PCT / EP2023 / 058980, the entire contents of which are incorporated herein by reference.

[0030] Projector unit A projector unit can be understood herein as a device configured to project light onto a surface, such as the surface of a three-dimensional object. In a preferred embodiment, the projector unit is configured to project a light pattern onto the surface of a dental object. Preferably, the projector unit is configured to project a light pattern such that the light pattern is focused at a predefined focal length or focus range measured along the projector's optical axis. The projected pattern can be focused within a predefined depth of field of the scanner. The projector unit can be configured to project unpolarized light.

[0031] The projector unit may include a digital light processing (DLP) projector that uses a micromirror array to generate time-varying patterns, or a diffractive optical element (DOE), or a front-illuminated reflective mask projector, or a micro-LED projector, or a liquid crystal on silicon (LCoS) projector, or a back-illuminated mask projector, wherein the light source is placed behind a mask having a spatial pattern, thereby patterning the light projected onto the surface of the dental object. The pattern can be dynamic, i.e., changing over time, or the pattern can be time-static, i.e., remaining constant over time. The advantage of projecting a static pattern is that it allows all image data to be captured simultaneously, thus preventing warping caused by movement between the scanner and the object.

[0032] The projector unit may include one or more collimating lenses for collimating light from a light source. The collimating lenses (one or more) may be positioned between the light source and a mask. In some embodiments, the one or more collimating lenses are Fresnel lenses. The projector unit may further include one or more focusing lenses or lens elements configured to focus light at a predefined working distance or focus range, such as that defined by the depth of field of a scanner. In some embodiments, the projector unit includes a projector lens stack comprising a plurality of lens elements. The projector lens stack may define a projector optical axis. In some embodiments, the lens elements of the projector lens stack are attached together to form a single unit.

[0033] In a preferred embodiment, the projector unit of the scanner includes at least one light source and a pattern generating element for defining a light pattern. The pattern generating element is preferably configured to generate a light pattern to be projected onto the surface of one or more objects, such as a patient's dentition. As an example, the pattern generating element may be a mask with a spatial pattern. Therefore, the projector unit may include a mask configured to define a light pattern. The mask may be placed between the light source of the projector unit and one or more focusing lenses, such that light transmitted through the mask is patterned into a light pattern. As an example, the mask may define a polygonal pattern comprising multiple polygons, such as a checkerboard pattern. The projector unit may further include one or more lenses, such as collimating lenses or projection lenses. In other embodiments, the pattern generating element generates the light pattern based on diffraction and / or refraction, such as a pattern comprising a discrete, unconnected array of dots.

[0034] Preferably, the projector unit is configured to generate a predefined static pattern that can be projected onto a surface. Alternatively, the projector unit can be configured to generate a dynamic pattern that varies over time. The projector unit can be associated with its own projector plane, which is determined by the projector optics. As an example, if the projector unit is a back-illuminated mask projector, the projector plane can be understood as a plane containing the mask. The projector plane can include multiple pattern features of the projected pattern. Preferably, the camera unit and the projector unit are arranged such that the image sensor and the projector plane (e.g., defined by the mask) are in the same plane.

[0035] The projector unit can be configured to project multiple projector rays onto the surface of the object to be scanned. Solving the correspondence problem may include the step of determining image features within a set of images and further associating those image features with specific projector rays. In a preferred embodiment, the correspondence problem is solved jointly for a group of projector rays, rather than, for example, solving the correspondence problem individually for each projector ray. The inventors have discovered that by solving the correspondence problem jointly for a group or set of projector rays, a particularly reliable and robust solution can be obtained, resulting in a more accurate 3D representation. The depth of each projector ray can then be calculated, thereby generating a 3D representation of the scanned object.

[0036] The projector unit may include one or more light sources. The projector unit can be configured to project a light pattern defined by multiple projector rays when the one or more light sources are turned on / active. The projector unit can be configured to subsequently turn the light sources on and off at a predetermined frequency, wherein the light sources are on for a predetermined time period. The one or more light sources can be configured to generate light of a single wavelength or a combination of wavelengths (monochromatic or polychromatic). The wavelength combination can be generated by the light source, which is configured to generate light including different wavelengths or wavelength ranges (e.g., white light). The light source can be configured to generate unpolarized light, such as unpolarized white light.

[0037] In some embodiments, each projector unit includes a light source for generating white light. The advantage is that white light enables the scanner to simultaneously acquire data or information related to both surface geometry and surface color. Therefore, the same set of images can be used to provide, for example, both the geometry and color of an object in terms of 3D data / 3D representation. Thus, alignment between data related to the recorded surface geometry and data related to the recorded surface color is not required to generate a digital 3D representation of the object that represents both its color and geometry. Alternatively, the projector unit may include multiple light sources, such as LEDs, that individually generate light of different wavelengths (e.g., red, green, and blue), which can be combined to form light comprising different wavelengths. Therefore, the light generated by one or more light sources can be defined by wavelengths that define a specific color, or by a range of different wavelengths that define combinations of colors, such as white light. In some embodiments, the light source is a diode, such as a white light-emitting diode or a laser diode. In some embodiments, the projector unit includes a laser, such as a blue or green laser diode for generating blue or green light, respectively. The advantage is that a more efficient projector unit can be achieved, resulting in faster exposure compared to using, for example, a white light-emitting diode.

[0038] Projected pattern A projector unit can be configured to project a light pattern defined by a plurality of projector rays when the light source of the projector unit is turned on. The terms 'illumination pattern', 'light pattern', and 'projection pattern' are used interchangeably herein. The projection pattern can be generated using, for example, a pattern generating element located in the projector unit. The pattern generating element can be a mask with a spatial pattern, such as a transparent or transmissive mask. The mask can be a chromium photomask. In other embodiments, the pattern generating element includes one or more diffractive optical elements (DOEs) configured to generate the light pattern using diffraction and / or refraction. Using light patterns can lead to correspondence problems, where it is necessary to determine the correspondence between points in the light pattern and points seen by one or more camera units viewing the pattern. In some embodiments, the correspondence problem is addressed jointly for a group of projector rays emitted from the projector unit.

[0039] The projected pattern can be a polygonal pattern comprising multiple polygons. The polygons can be selected from the group consisting of triangles, rectangles, squares, pentagons, hexagons, and / or combinations thereof. Other polygons are also conceivable. Generally, polygons consist of sides and angles. In a preferred embodiment, the polygons are repeated in a predefined manner within the pattern. As an example, the pattern may include multiple repeating units, each repeating unit comprising a predefined number of polygons, wherein the repeating units are repeated throughout the pattern. Alternatively, the pattern may include a predefined arrangement comprising one or more stripes, squares, dots, triangles, rectangles, and / or combinations thereof. In some embodiments, the pattern is uncoded such that no part of the pattern is unique.

[0040] In some embodiments, the generated light pattern is a polygonal pattern, such as a checkerboard pattern comprising multiple squares. Similar to a common checkerboard pattern, the squares in the pattern may have alternating dark and bright areas corresponding to low-intensity (dark) areas and (higher)-intensity (bright) areas. In some embodiments, the light pattern is a checkerboard pattern comprising alternating squares of dark and bright light (i.e., different intensities). In other embodiments, the light pattern comprises a distribution of discrete, unconnected light points.

[0041] The pattern preferably comprises multiple pattern features. These pattern features can be arranged in a regular grid. In some embodiments of the currently disclosed scanners, the total number of pattern features in the pattern is at least 1000, preferably at least 3000, more preferably at least 10000, and even more preferably at least 15000. When a pattern comprising such pattern features is projected onto the surface of a 3D object, the acquired image of the object will similarly comprise multiple image features corresponding to the pattern features. A pattern / image feature can be understood as a single, well-defined location within a pattern / image. Examples of image / pattern features include corners, edges, vertices, points, transition points, dots, stripes, etc. In some embodiments, the image / pattern features constitute corners in a polygonal pattern, such as the corners of squares in a checkerboard pattern.

[0042] mirror The scanner may further include a mirror arranged in combination with a given scanning unit. The mirror is preferably configured to reflect light from the projector unit of the scanning unit and / or from the surface of a dental object onto one or more image sensors of each camera unit of the scanning unit associated with the mirror. In a preferred embodiment, the scanner includes or constitutes an elongated probe defining the longitudinal axis of the scanner. In some embodiments, the height of the mirror, as seen along the projector optical axis, is between about 13 mm and about 20 mm. This has the advantage that the scanner tip height is kept to a minimum, particularly for working distances greater than 15 mm. Therefore, the mirror allows a portion of the optical path to be folded or redirected within the scanner, enabling the scanner to accommodate an optical system, such as the scanning unit, with a working distance greater than the intended height of the scanner's probe or tip. Consequently, the tip or probe can be made smaller, particularly the height of the probe, making it easier to enter, for example, the patient's oral cavity. A smaller probe also makes it easier to capture data from the posterior part of the patient's oral cavity.

[0043] Reference mark Intraoral scanners may include a pattern of reference markers arranged in a predefined layout, such as a two-dimensional arrangement. The reference marker pattern may be placed in the optical path of the scanner, such as on or within the surface of the scanner's transparent window. Reference markers can be understood as objects placed in the field of view of the imaging system and appearing in the resulting image, used as reference points or measurements. The reference markers utilized may preferably be substantially two-dimensional objects, for example, located on the surface of the transparent window of the intraoral scanner. Advantageously, the reference markers are disposed on or inside the transparent window. Reference markers can resemble any geometric shape, such as squares, rectangles, circles, dots, triangles, hexagons, crosses, and / or combinations thereof. In particular, reference markers may have predefined geometric shapes selected from the group consisting of polygonal shapes, rectangular shapes, triangular shapes, cross shapes, rhombus shapes, circular shapes, line shapes, and / or combinations thereof.

[0044] Markings can be manufactured using a variety of techniques suitable for creating predefined patterns on or within the surface of a material, such as etching, engraving, abrasive blasting, printing, coating, electroplating, micromachining, micromilling, and / or combinations thereof.

[0045] As an example of how a reference mark pattern can be generated in a transparent window, a laser engraving machine or a chemical etching process can be used to selectively remove material from the transparent window to create the desired reference mark pattern. As another example, a mask can be placed on the transparent window to cover areas where the pattern should not be present, and then sandblasting, chemical etching, or abrasive blasting can be used to remove material from the exposed areas, leaving the pattern. As yet another example, screen printing, inkjet printing, or other printing methods can be used, or a special ink or coating can be adhered to the transparent surface to form a predefined pattern. As yet another example, ultraviolet (UV) lithography and a suitable etchant can be used to etch the pattern. As yet another example, precision machining tools or micro-milling machines can be used to remove material from the transparent window and create the desired pattern with micron-level accuracy.

[0046] In some embodiments, the reference marker is illuminated by an intraoral scanner during use of the scanner, such as by one or more projector units of the scanner. The advantage is that the reference marker is illuminated with known illumination. Therefore, the reference marker appears more similar across multiple sets of images acquired at different times. Thus, the reproducibility of the marker in the images is enhanced by illuminating the reference marker with an internal light source of the scanner, provided, for example, by one or more projector units of the scanner. In cases where the imaged reference marker changes over time, i.e., across multiple sets of acquired images, this can indicate that the geometric relationships between one or more scanner components have changed. In response, the scanner is preferably configured to automatically recalibrate the scanner by adjusting one or more parameters of the scanner's geometric model, as outlined elsewhere herein.

[0047] case Intraoral scanners may include a housing, such as an elongated housing, wherein the distal end of the housing is adapted for insertion into the oral cavity of a subject. In particular, the housing may resemble an elongated probe, wherein the distal end of the probe is configured for insertion into the oral cavity, such as in a human mouth, to acquire images and / or 3D data of a person's teeth. The housing may be manufactured as one or more components. In some embodiments, the housing is manufactured as a single component. The housing is preferably composed of one or more polymers, such as those selected from the group consisting of: acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), polyethylene (PE): high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), or polymethyl methacrylate (PMMA). Other materials are contemplated without departing from the scope of this disclosure.

[0048] Transparent window The intraoral scanner disclosed herein may include a transparent window. In a preferred embodiment, a reference marker pattern is arranged in or on the surface of the window. The transparent window may be located in the distal end of the scanner, such as within the scanner housing. In some embodiments, the window is substantially flush with the surface of the housing.

[0049] The transparent window can be made of various materials suitable for creating the transparent area, allowing light to pass through it. As an example, the transparent window can be made of a glass material such as sapphire. As another example, the window can be made of a polymer such as poly(methyl methacrylate) (PMMA). Preferably, the window is made of a rigid material such as those described above. The window is preferably made substantially planar and is fixedly mounted within the housing of the intraoral scanner disclosed herein.

[0050] Figure 10 The outline of a transparent window is shown, in which a predefined arrangement of reference markers is placed within the window. The markers may be placed near the edges of the window to allow a projected light pattern to transmit through one or more areas of the window, ideally without being obstructed by the reference marker pattern. Therefore, in some embodiments, the reference marker pattern is located outside the projected pattern so that it does not overlap with it.

[0051] (one or more) processors According to some embodiments, the scanner includes one or more processors, such as those selected from the group consisting of: central processing unit (CPU), accelerator (offload engine), general-purpose microprocessor, graphics processing unit (GPU), neural processing unit (NPU), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), advanced RISC machine (ARM), dedicated logic circuit, dedicated artificial intelligence processor unit and / or combinations thereof.

[0052] One or more processors may be configured to perform at least partially any of the methods disclosed herein, such as a method for recalibrating an intraoral scanner. As an example, the processor(s) may be configured to perform the steps of: determining a difference between an imaging reference marker pattern and a predefined arrangement of said reference markers; determining, based on the determined difference, whether the geometric relationship between the scanning unit and / or camera unit has changed; and correcting the geometric relationship in the geometric model of the intraoral scanner based on the determined difference, thereby recalibrating the scanner.

[0053] The scanner may further include a computer memory for storing instructions, which, when executed, cause one or more processors to perform the step of determining a difference between an imaged reference marker pattern and a predefined arrangement of said reference markers. The computer memory may further store instructions, when executed, causing one or more processors to perform the steps of: determining, based on the determined difference, whether the geometric relationship between the scanning unit and / or camera unit has changed, and correcting the geometric relationship in the geometric model of the intraoral scanner based on the determined difference, thereby recalibrating the scanner.

[0054] One or more processors may be located on the scanner or they may be part of an external computer system that forms part of the disclosed 3D scanner system. The processors may be operatively connected such that a first processor provides input to a second processor. Some steps of the processing, such as some steps of the disclosed calibration method, may be performed on the scanner, and other steps of the method may be performed by the computer system.

[0055] Module for transmitting data The scanner preferably includes a module for transmitting data to one or more external devices, or one or more external devices such as a computer system. The module may be a wireless module configured to wirelessly transmit data from the scanner to the computer system. The wireless module may be configured to perform various functions required for the scanner to communicate wirelessly with a computer network. The wireless module may utilize one or more of an integrated TCP / IP protocol stack / IEEE 802.11 Wi-Fi protocol that allows the scanner to access the computer network. The wireless module may include a system-on-a-chip with different types of built-in network connectivity technologies. These may include commonly used wireless protocols such as Bluetooth, ZigBee, Wi-Fi, WiGig (also known as 60 GHz Wi-Fi), etc. The scanner may be further or alternatively configured to transmit data using a wired connection, such as via an Ethernet cable or USB cable. The scanner may be configured to continuously transmit data during a scanning session. It may be further configured to transmit the data in real time.

[0056] Computer System A computer system can be understood as an electronic processing device used to perform a sequence of arithmetic or logical operations. In the context of this document, a computer system refers to one or more devices that include at least one processor, such as a central processing unit (CPU), and some type of computer memory. Examples of computer systems falling under this definition include desktop computers, laptop computers, computer clusters, servers, cloud computers, quantum computers, mobile devices such as smartphones and tablets, and / or combinations thereof.

[0057] A computer system may include hardware such as one or more central processing units (CPUs), graphics processing units (GPUs), and computer memory such as random access memory (RAM) or read-only memory (ROM). The computer system may include a CPU configured to read and execute instructions stored in computer memory, such as in the form of random access memory. The computer memory may be configured to store instructions for execution by the CPU and data used by those instructions. As an example, the memory may store instructions that, when executed by the CPU, cause the computer system to perform, wholly or partially, any of the computer-implemented methods disclosed herein. The computer system may further include a graphics processing unit (GPU). The GPU may be configured to perform various tasks, such as video decoding and encoding, 3D representation rendering, and other image processing tasks.

[0058] The computer system may further include non-volatile storage in the form of a hard disk drive. Preferably, the computer system further includes an I / O interface configured to connect peripheral devices used in connection with the computer system. More specifically, a display may be connected and configured to display output from the computer system. The display may, for example, display a 2D rendering of a generated digital 3D representation. Input devices may also be connected to the I / O interface. Examples of such input devices include a keyboard and mouse, which allow the user to interact with the computer system. A network interface may further be part of the computer system to allow the computer system to connect to a suitable computer network to receive and transmit data (such as scan data and images) to and from other computing devices. Scan data may include or constitute 3D data, such as depth maps or point clouds, or it may include 2D data, such as images. The CPU, volatile memory, hard disk drive, I / O interface, and network interface may be connected together via a bus.

[0059] The computer system is preferably configured to receive data from a scanner, either directly from the scanner or via a computer network, such as a wireless network. The data may include images, processed images, point clouds, data point sets, or other types of data. Wireless connections, wired connections, and / or combinations thereof may be used to transmit / receive the data. In some embodiments, the computer system is configured to generate a digital 3D representation of a three-dimensional (3D) object as described herein. In some embodiments, the computer system is configured to receive data, such as point cloud data, from a scanner and then subsequently perform steps of reconstructing and rendering the digital 3D representation of the three-dimensional (3D) object. Rendering can be understood as the process of generating one or more images from three-dimensional data. The computer system may include computer memory for storing computer programs, which include computer-executable instructions that, when executed, cause the computer system to perform any of the methods disclosed herein.

[0060] The methods outlined The first step of the method may be to acquire two or more sets of images using an intraoral scanner. Multiple sets of images can be acquired by individual scanning units of the intraoral scanner, where each scanning unit includes one or more camera units. Each set of images may include multiple two-dimensional images, such as at least one image from each camera unit of a given scanning unit. As an example, in the case where the scanning unit includes four camera units, a set of images may include four images. In the case of two scanning units, two sets of such multiple sets of images can preferably be acquired simultaneously. The camera units may have at least partially overlapping fields of view, such that the acquired images can similarly have overlapping fields of view. Therefore, the reflected projection pattern of the scanned object can ideally be visible in all images within a set of images. Furthermore, at least a portion of the reference mark pattern should be present in the images. Ideally, the entire reference mark pattern is imaged jointly by the camera units, but the entire pattern does not need to appear in every image within a set of images. This is in Figure 10 The diagram illustrates the outline of a transparent window, the overlapping field of view of the camera unit, and a reference marker pattern placed within the window. Therefore, the reference marker pattern can appear in multiple sets of images, thereby generating an imaged reference marker pattern.

[0061] Another step of the method may be to determine the difference between the imaged reference marker pattern and a predefined arrangement of the reference markers. As an example, the determined difference may be selected from the group consisting of: the position of the reference markers, the size of the reference markers, the orientation of the reference markers, and / or combinations thereof. For a perfectly calibrated intraoral scanner, ideally, there will be no difference between the imaged reference marker pattern in the transparent window and the predefined arrangement of the reference markers. Therefore, the geometry, size, and position of the markers are all predefined and known a priori. Any difference in one or more of the parameters in the subset of markers will indicate some deviation from the perfect calibration of the scanner. Such deviation may, for example, originate from thermal drift or thermal expansion in one or more of the scanner's components (optical, electrical, etc.). Therefore, the scanner is preferably configured to automatically detect and determine the difference between the imaged reference marker pattern and the predefined arrangement during use.

[0062] In the same step, or in a subsequent step, the scanner may be configured to determine, based on the identified differences, whether the geometric relationships between the scanner's scanning units and / or camera units have changed. As previously mentioned, the scanner may include two or more scanning units, each including one or more camera units, wherein the scanning units are positioned with predefined, known geometric relationships. Figure 1 An embodiment of this scanner is shown, in which two scanning units are positioned adjacent to each other in series. Therefore, the position and orientation of each scanning unit are predefined. The position and orientation can collectively be referred to as the pose of a given scanning unit. Figure 6 The image shows an example of how poses can be defined.

[0063] Another step in the method can be to calibrate the scanner by correcting the geometric relationships in the geometric model of the intraoral scanner based on the identified differences. The geometric model of the intraoral scanner can define various parameters of the scanner's imaging / optical system to capture accurate 3D data and reconstruct the scanned object. As an example, the geometric model may include one or more calibration parameters related to the camera unit, such as intrinsic parameters (focal length, principal point, etc.) and extrinsic parameters (camera position and orientation). The geometric model may further include parameters related to the optics of the imaging system, such as focal length, depth of field, field of view, aperture, image sensor size, pixel size, lens distortion, illumination model, etc.

[0064] Specifically, the geometric model can describe the pose of each scanning unit and / or the relative pose between scanning units. The pose of a given scanning unit can include the position and orientation of the scanning unit. The orientation of a given scanning unit can be defined by the optical axis of a projector unit that forms part of the scanning unit. In some embodiments, the geometric relationship between the scanning unit and / or camera unit is corrected based on a Euclidean transformation of the pose (position and / or orientation) of at least one scanning unit. The Euclidean transformation can have at least three degrees of freedom, or in some cases at least six degrees of freedom. The Euclidean transformation can include one or more rotations, translations, reflections, or any sequence thereof.

[0065] Therefore, the geometric model can be updated by adjusting the values ​​of one or more of the parameters, such as the position and / or orientation of the scanning unit, in response to the determined differences. It can also be the position and / or orientation of one or more camera units of a given scanning unit, which is adjusted to correct the geometric relationships. Some of the parameters of the geometric model can be fixed, while others can vary freely within a predefined range. Parameter adjustments can be performed continuously during scanning, enabling the currently disclosed systems and methods to achieve real-time and dynamic calibration of intraoral scanners.

[0066] Detailed Explanation of the Diagram Figure 1 An embodiment of an intraoral scanner 1 according to the present disclosure is shown. In this embodiment, the scanner 1 includes a housing 2 having a distal end for insertion into the oral cavity, and a transparent window 3 located in the distal end of the housing, wherein the transparent window includes a reference marker pattern (not shown) arranged in a predefined arrangement. The intraoral scanner 1 further includes two or more scanning units 5 located in the housing 2, each scanning unit 5 including one or more camera units, specifically four in this embodiment, the one or more camera units being configured to acquire a set of images including at least one image from each camera unit, wherein at least a portion of the reference marker pattern is imaged by the camera unit. The intraoral scanner further includes a mirror 8 for each scanning unit arranged in front of each scanning unit 5, such that light projected by (one or more) scanning units is directed away from the transparent window 3 onto the object to be scanned. Similarly, light reflected from the surface of the scanned object can be reflected by the mirror 8 and redirected back to the camera unit of each scanning unit 5. The reference marker pattern in the transparent window 3 can be as follows: Figures 9 to 10 As shown in the image.

[0067] Figure 2An exploded view of some components of an intraoral scanner 1 according to an embodiment of the present disclosure is shown. In this embodiment, the scanner includes two scanning units 5, each scanning unit including a plurality of camera units 6 and a plurality of flexible printed circuit boards (PCBs) 12 connected between the camera units 6 and a main PCB (not shown). The scanner further includes a rigid frame 9 for receiving the scanning units 5, such that they can be mounted in the frame 9. The frame may be manufactured as a single component. The frame may be further configured to receive and house mirrors 8, wherein each mirror is arranged in combination with the scanning units 5, as per [reference to...]. Figure 1 The explanation.

[0068] Figure 3 An embodiment of an intraoral scanner 1 according to the present disclosure is shown. In this embodiment, the scanner 1 includes a housing 2 having a distal end for insertion into the oral cavity, and a transparent window 3 located in the distal end of the housing, wherein the transparent window includes a reference mark pattern (not shown) arranged in a predefined arrangement. In this embodiment, the scanner further includes a battery (not shown) and a port 14 for charging the battery and / or for transmitting data via a cable connected to the port.

[0069] Figure 4 An embodiment of an intraoral scanner 1 according to the present disclosure is shown. In this embodiment, the scanner 1 includes a housing 2 having a distal end for insertion into the oral cavity, and a transparent window 3 located in the distal end of the housing, wherein the transparent window includes a reference mark pattern (not shown) arranged in a predefined arrangement. In this embodiment, the scanner further includes a battery 13 and a port 14 for charging the battery and / or for transmitting data via a cable connected to the port. In this embodiment, the housing 2 can be disassembled into at least two parts, i.e., such that the housing 2 includes a removable portion in which the transparent window 3 is located. This is advantageous in cases where the window 3 needs to be replaced or repaired. Furthermore, the removable portion of the housing allows easy access to the battery compartment for housing the battery 13.

[0070] Figure 5 An embodiment of an intraoral scanner 1 according to the present disclosure is shown. In this embodiment, the scanner 1 includes a housing 2 having a distal end for insertion into the oral cavity, and a transparent window 3 located in the distal end of the housing, wherein the transparent window 3 includes a reference mark pattern (not shown) arranged in a predefined arrangement. The reference mark pattern in the transparent window 3 can be as follows: Figures 9 to 10As shown in the figure. In this figure, the housing 2 is made transparent for illustrative purposes. The intraoral scanner 1 further includes two scanning units 5 located within the housing 2, each scanning unit 5 including one or more camera units configured to acquire a set of images from each camera unit, including at least one image, wherein at least a portion of a reference marker pattern is imaged by the camera unit. The intraoral scanner further includes a mirror 8 for each scanning unit arranged in front of each scanning unit 5, such that light projected by the scanning unit(s) is directed away from the transparent window 3 onto the object to be scanned. Similarly, light reflected from the surface of the scanned object can be reflected by the mirror 8 and redirected back to the camera unit of each scanning unit 5. The scanner 1 further includes a battery 13 and a port 14 for charging the battery and / or for transmitting data via a cable connected to the port.

[0071] Figure 6 An embodiment of a scanning unit 5 according to this disclosure is shown. In this embodiment, the scanning unit includes a projector unit 10 for projecting a predefined pattern and a plurality of camera units 6 (four camera units are illustrated herein). The projector unit 10 has an optical axis 11 corresponding to the line of sight of the central ray projected by the projector unit and / or corresponding to the radial axis of symmetry of the projector unit. The figure further illustrates the orientation of the scanning unit, which includes position and orientation. The orientation is defined by a Cartesian coordinate system (…). x , y , z The indicator shows that optical axis 11 coincides with one of the axes, which is exemplified here as... z The coordinate system is defined by the axis. Therefore, the position and orientation of the scanning unit can be defined by the indicated coordinate system. However, other origins and other orientations of the coordinate system can be chosen, as long as the pose (position / or orientation) is predefined. Then, any deviation from the predefined pose and / or any deviation in the relative pose between the two scanning units can be used to infer that their relative geometric relationship has changed, for example, due to thermal drift / expansion. The two scanning units can also be defined in a common coordinate system.

[0072] Figure 7 An embodiment of a 3D scanner system according to the present disclosure is shown. In this embodiment, the scanner system includes an intraoral scanner 1 having a distal end for insertion into the oral cavity, thereby enabling the scanning of one or more dental objects 15. The scanner includes a transparent window 3 at the distal end of the scanner. The system further includes a computer system 16 for generating 3D representations of the dental objects(s), such as a 3D representation of a patient's dentition, and / or for visualizing the 3D representations on a display. The scanner 1 may be configured to transmit data 17 to the computer system.

[0073] Figure 8 An embodiment of a 3D scanner system according to the present disclosure is illustrated. In this embodiment, the scanner system includes an intraoral scanner 1, which includes two scanning units 5 and a mirror 8 arranged in combination with each scanning unit. The scanner further includes a transparent window 3 located at the distal end of the scanner, wherein the transparent window includes a reference marker pattern (not shown) arranged in a predefined arrangement. The scanner system further includes one or more processors 7 configured to compare the imaged reference marker pattern with the predefined arrangement, thereby determining a difference; and / or to determine, based on the difference, whether the geometric relationship between the scanning units and / or camera units has changed; and / or to correct the geometric relationship in the geometric model of the intraoral scanner based on the difference, thereby calibrating the scanner. The processor 7 may be located on the intraoral scanner 1 or formed as part of an external computer system 16. The scanner system may further include a power supply 18 for powering the scanner 1 and / or for charging a battery located in the scanner. In this embodiment, the scanner includes a port 14 for charging and / or powering the scanner. The port 14 may additionally or alternatively be configured to transmit data 17 to the computer system 16. The scanner may include a transmission unit, such as a wireless module, for wirelessly transmitting data 17 to a computer system, for example, via a wireless network (Wi-Fi).

[0074] Figure 9 An embodiment of the pattern 19 to be projected and the reference mark pattern 4 is shown. In this embodiment, the projected pattern 19 resembles a checkerboard pattern, but other patterns (lines, dots, triangles, hexagons, etc.) are conceivable. Each reference mark is illustrated as a cross; however, other shapes may be utilized. Each scanning unit of the scanner may include a projector unit (not shown) for projecting the pattern 19. The scanner may further include a transparent window (not shown) in which the reference mark pattern 4 is positioned. Figure 6 An example of a scanning unit with a projector unit and multiple camera units is shown. The scanner system can be configured to calibrate the intraoral scanner based on a reference mark pattern 4 located in a transparent window.

[0075] Figure 10An embodiment of a transparent window 3 of an intraoral scanner as disclosed herein is shown. In this embodiment, the transparent window includes a reference marker pattern 4. Therefore, the reference marker pattern 4 is physically located within or on the window and thus does not form part of the projected pattern (not shown). As an example, the pattern 4 may be coated on the window 3 or form an integrated portion of the window. Furthermore, in this embodiment, the scanner includes two scanning units, each including multiple camera units (not shown), wherein at least a portion of the reference marker pattern 4 is imaged by (one or more) camera units. The field of view 20 of each camera unit is delineated in the figure. Thus, the scanner may include two or more camera units, such as four camera units, having at least partially overlapping fields of view 20 as indicated in the figure. The overlap between fields of view is indicated in the figure by shaded areas 21, which correspond to the common field of view of the camera units. In this embodiment, only a portion of the reference marker pattern 4 is visible in the field of view of a given camera unit. However, collectively, the camera units view / image all reference markers 4 in the pattern. The figure illustrates two sets of camera units with overlapping fields of view, where each set of four camera units belongs to a given scanning unit. Furthermore, a reference marker pattern 4 is associated with each scanning unit, such that the pattern 4 can be used to infer any deviations in the geometric relationship between the two scanning units. The scanner system may further include one or more processors 7 (not shown) configured to compare the imaged reference marker pattern with a predefined arrangement 4, thereby determining differences; and / or to determine, based on the differences, whether the geometric relationship between the scanning units has changed; and / or to calibrate the scanner by correcting the geometric relationship in the geometric model of the intraoral scanner based on the differences. The projection pattern may be similar to... Figure 9 The projection pattern shown is illustrated. It should be noted that this figure illustrates a predefined arrangement of reference marks. For a perfectly calibrated scanner, the imaged reference mark pattern will be exactly similar to the predefined arrangement.

[0076] Figure 11 An embodiment of a transparent window 3 of an intraoral scanner as disclosed herein is shown. In this embodiment, the transparent window includes a reference mark pattern 4. The reference mark pattern 4 is physically located within or on the window and therefore does not form part of the projection pattern 19. Similar to Figure 10This embodiment illustrates an overlapping camera field of view 20, such that the camera units jointly image the reference marker pattern 4 and the reflected projection pattern 19. In this embodiment, the two scanning units are arranged sequentially, i.e., they are placed adjacent to each other, such that they each project pattern 19 onto the same side of the scanner and preferably the patterns are closely aligned without overlapping. This is illustrated in the figure. In this embodiment, a total of six reference markers are placed in or on window 3; however, other numbers of reference markers are contemplated without departing from the scope of this disclosure. It should be noted that even though the projection pattern 19 is shown in the figure, it does not form part of the transparent window 3. Instead, it is projected through the transparent window 3 during use of the intraoral scanner. Here, the projection pattern 19 is illustrated as a checkerboard pattern. However, other patterns, such as polygonal, striped, or dotted patterns, are contemplated without departing from the scope of this disclosure.

[0077] Further details of the invention 1. A 3D scanner system, comprising: - Intraoral scanner (1), including: - A housing (2), the housing having a distal end for insertion into the oral cavity; - A transparent window (3), the transparent window being located in the distal end of the housing, wherein the transparent window includes a reference mark pattern (4) arranged in a predefined arrangement; The intraoral scanner further includes one or more scanning units (5) located within the housing, each scanning unit comprising: - One or more camera units (6), the one or more camera units being configured to acquire a set of images including at least one image from each camera unit, wherein at least a portion of the reference marker pattern is imaged by the one or more camera units; - One or more processors (7), said one or more processors being configured to: - By comparing the reference mark pattern of the image with the predefined arrangement, differences can be determined; - Based on the differences, determine whether the geometric relationship between the scanning unit and / or the camera unit has changed; and - The geometric relationships in the geometric model of the intraoral scanner are corrected based on the differences, thereby calibrating the scanner.

[0078] 2. The scanner system according to Clause 1, wherein the intraoral scanner comprises two or more scanning units.

[0079] 3. The scanner system according to any one of the preceding clauses, wherein the geometric relationship includes the orientation of each scanning unit and / or the relative orientation between the scanning units.

[0080] 4. The scanner system according to Clause 3, wherein a given orientation of the scanning unit includes the position and orientation of the scanning unit.

[0081] 5. The scanner system according to Clause 4, wherein the orientation of a given scanning unit is defined by the optical axis of a projector unit forming part of the scanning unit.

[0082] 6. The scanner system according to any one of the preceding clauses, wherein the geometric relationship between the scanning unit and / or camera unit is corrected based on the Euclidean transformation of the orientation of at least one scanning unit or camera unit.

[0083] 7. The scanner system according to Clause 6, wherein the Euclidean transformation has at least three degrees of freedom.

[0084] 8. The scanner system according to Clause 6, wherein the Euclidean transformation has at least six degrees of freedom.

[0085] 9. The scanner system according to any one of the preceding clauses, wherein the determined difference is selected from the group consisting of: the position of the reference mark, the size of the reference mark, the orientation of the reference mark and / or a combination thereof.

[0086] 10. The scanner system according to any one of the preceding clauses, wherein each scanning unit of the intraoral scanner comprises two or more camera units.

[0087] 11. The scanner system according to any one of the preceding clauses, wherein each scanning unit of the intraoral scanner comprises four or more camera units.

[0088] 12. The scanner system according to any one of clauses 10 to 11, wherein the camera unit is configured to acquire a set of images, the set of images including at least one image from each camera unit.

[0089] 13. The scanner system according to any one of clauses 10 to 12, wherein the camera unit is configured to simultaneously acquire images that form a portion of the set of images.

[0090] 14. The scanner system according to any one of the preceding clauses, wherein each camera unit includes an image sensor and one or more focusing lenses for focusing light onto the image sensor.

[0091] 15. The scanner system according to any one of the preceding clauses, wherein the intraoral scanner further comprises one or more projector units configured to project a pattern through the transparent window.

[0092] 16. The scanner system according to Clause 15, wherein one or more projector units include a mask for defining the pattern.

[0093] 17. The scanner system according to any one of Clauses 15 to 16, wherein the projected pattern is a checkerboard pattern.

[0094] 18. The scanner system according to any one of clauses 15 to 17, wherein the reference mark pattern is aligned to the pattern projected through the transparent window.

[0095] 19. The scanner system according to any one of Clauses 15 to 18, wherein the reference mark pattern is located outside the projection pattern such that it does not overlap with the projection pattern.

[0096] 20. The scanner system according to any one of Clauses 15 to 19, wherein the projected pattern includes a plurality of blank spaces for surrounding the reference mark.

[0097] 21. The scanner system according to any one of Clauses 15 to 20, wherein the reference mark pattern is completely enclosed within the projected pattern.

[0098] 22. The scanner system according to any one of clauses 15 to 21, wherein the projector unit is configured to illuminate reference marks.

[0099] 23. The scanner system according to any one of Clauses 15 to 22, wherein the geometric relationship is corrected by adjusting the position and / or orientation of one or more camera units relative to each other and / or relative to the projector unit.

[0100] 24. The scanner system according to any one of the preceding clauses, wherein the reference mark has a predefined geometry selected from the group consisting of: polygonal shape, rectangular shape, triangular shape, cross shape, rhombus shape, circular shape, line shape and / or combinations thereof.

[0101] 25. The scanner system according to any one of the preceding clauses, wherein the transparent window is made of glass such as sapphire.

[0102] 26. The scanner system according to any one of the preceding clauses, wherein the transparent window is made of a polymer such as poly(methyl methacrylate) (PMMA).

[0103] 27. The scanner system according to any one of the preceding clauses, wherein one or more processors are configured to continuously calibrate the intraoral scanner during use based on continuously correcting the geometric relationships.

[0104] 28. The scanner system according to any one of the preceding clauses, wherein one or more processors are configured to calibrate the intraoral scanner in real time during use of the scanner.

[0105] 29. A method for recalibrating an intraoral scanner, the method comprising the following steps: - Acquire two or more sets of images, wherein the sets of images are acquired by individual scanning units of the intraoral scanner, each scanning unit including one or more camera units, wherein each set of images contains a reference marker pattern; - Determine the difference between the imaging reference mark pattern and the predefined arrangement of the reference marks; - Determine whether the geometric relationship between the scanning unit and / or the camera unit has changed based on the identified differences; and - The geometric relationships in the geometric model of the intraoral scanner are corrected based on the determined differences, thereby recalibrating the scanner.

[0106] 30. The method according to Clause 29, wherein the geometric relationship is corrected continuously and in real time.

[0107] 31. The method according to any one of clauses 29 to 30, wherein the steps of the method are performed continuously and in real time.

[0108] 32. The method according to any one of clauses 29 to 31, wherein the reference marker pattern is located in the window of the intraoral scanner.

[0109] 33. The method according to any one of clauses 29 to 32, wherein the geometric relationship includes the orientation of each scanning unit and / or the relative orientation between the scanning units.

[0110] 34. The method according to Clause 33, wherein a given orientation of the scanning unit includes the position and orientation of the scanning unit.

[0111] 35. The method according to any one of clauses 29 to 34, wherein the geometric relationship includes the pose of each camera unit and / or the relative pose between the camera units.

[0112] 36. The method according to Clause 35, wherein a given pose of the camera unit includes the position and orientation of the scanning unit.

[0113] 37. The method according to clause 34, wherein the orientation of a given scanning unit is defined by the optical axis of a projector unit forming part of the scanning unit.

[0114] 38. The method according to any one of clauses 29 to 37, wherein the geometric relationship between the scanning unit and / or the camera unit is corrected based on the Euclidean transformation of the pose of at least one scanning unit.

[0115] 39. The method according to any one of clauses 29 to 38, wherein the geometric relationship between the camera units is corrected based on the Euclidean transformation of the pose of at least one camera unit.

[0116] 40. The scanner system according to Clause 39, wherein the Euclidean transformation has at least three degrees of freedom.

[0117] 41. The scanner system according to Clause 39, wherein the Euclidean transformation has at least six degrees of freedom.

[0118] 42. The method according to any one of clauses 29 to 41, wherein the determined difference is selected from the group consisting of: the position of the reference mark, the size of the reference mark, the orientation of the reference mark and / or a combination thereof.

[0119] Although some embodiments have been described in detail and illustrated, this disclosure is not limited to such details, but may be embodied in other ways within the scope of the subject matter defined in the following claims. In particular, it should be understood that other embodiments may be utilized, and structural and functional modifications may be made without departing from the scope of this disclosure. Furthermore, those skilled in the art will appreciate that, unless the embodiments are presented specifically as alternatives only, different disclosed embodiments may be combined to achieve a particular implementation within the scope of this disclosure.

[0120] Figure Labels 1. Intraoral scanner 2. Shell 3. Transparent window 4. Reference Marker Pattern 5. (One or more) scanning units 6. (One or more) camera units 7. (One or more) processors 8. (One or more) mirrors 9. Framework 10. Projector Unit 11. Optical axis of the projector unit 12. (One or more) flexible PCBs 13. Battery 14. Port for charging and / or data transmission 15. (One or more) dental objects 16. Computer System 17. Data Transmission 18. Power supply 19. Projected pattern 20. Field of view of the camera unit 21. Common field of view of camera units

Claims

1. A 3D scanner system, comprising: - Intraoral scanner (1), including: - A housing (2), the housing having a distal end for insertion into the oral cavity; - A transparent window (3), the transparent window being located in the distal end of the housing, wherein the transparent window includes a reference mark pattern (4) arranged in a predefined arrangement; The intraoral scanner further includes one or more scanning units (5) located within the housing, each scanning unit comprising: - One or more camera units (6), the one or more camera units being configured to acquire a set of images including at least one image from each camera unit, wherein at least a portion of the reference marker pattern is imaged by the one or more camera units; - One or more processors (7), said one or more processors being configured to: i. By comparing the imaged reference mark pattern with the predefined arrangement, differences can be determined; ii. Determine whether the geometric relationship between the scanning unit and / or the camera unit has changed based on the difference; and iii. Based on the said differences, correct the geometric relationships in the geometric model of the intraoral scanner, thereby calibrating the scanner.

2. The scanner system according to claim 1, wherein, The intraoral scanner includes two or more scanning units.

3. The scanner system according to any one of the preceding claims, wherein, The geometric relationship includes the orientation of each scanning unit and / or the relative orientation between the scanning units.

4. The scanner system according to claim 3, wherein, The given orientation of the scanning unit includes the position and orientation of the scanning unit.

5. The scanner system according to claim 4, wherein, The orientation of a given scanning unit is defined by the optical axis of a projector unit that forms part of the scanning unit.

6. The scanner system according to any one of the preceding claims, wherein, The geometric relationship between the scanning unit and / or camera unit is corrected based on the Euclidean transformation of the orientation of at least one scanning unit or camera unit.

7. The scanner system according to claim 6, wherein, The Euclidean transformation has at least three degrees of freedom.

8. The scanner system according to claim 6, wherein, The Euclidean transformation has at least six degrees of freedom.

9. The scanner system according to any one of the preceding claims, wherein, The determined differences are selected from the group consisting of: the position of the reference mark, the size of the reference mark, the orientation of the reference mark, and / or combinations thereof.

10. The scanner system according to any one of the preceding claims, wherein, Each scanning unit of the intraoral scanner includes two or more camera units.

11. The scanner system according to any one of the preceding claims, wherein, Each scanning unit of the intraoral scanner includes four or more camera units.

12. The scanner system according to any one of claims 10 to 11, wherein, The camera unit is configured to acquire a set of images, which includes at least one image from each camera unit.

13. The scanner system according to any one of claims 10 to 12, wherein, The camera unit is configured to simultaneously acquire the images that form a portion of the set of images.

14. The scanner system according to any one of the preceding claims, wherein, Each camera unit includes an image sensor and one or more focusing lenses for focusing light onto the image sensor.

15. The scanner system according to any one of the preceding claims, wherein, The intraoral scanner further includes one or more projector units configured to project a pattern through the transparent window.

16. The scanner system according to claim 15, wherein, One or more projector units include a mask for defining the pattern.

17. The scanner system according to any one of claims 15 to 16, wherein, The projected pattern is a checkerboard pattern.

18. The scanner system according to any one of claims 15 to 17, wherein, The reference mark pattern is aligned with the pattern projected through the transparent window.

19. The scanner system according to any one of claims 15 to 18, wherein, The reference mark pattern is located outside the projection pattern so that it does not overlap with the projection pattern.

20. The scanner system according to any one of claims 15 to 19, wherein, The projection pattern includes a plurality of blank spaces for surrounding the reference mark.

21. The scanner system according to any one of claims 15 to 20, wherein, The reference mark pattern is completely enclosed within the projected pattern.

22. The scanner system according to any one of claims 15 to 21, wherein, The projector unit is configured to illuminate the reference mark.

23. The scanner system according to any one of claims 15 to 22, wherein, The geometric relationship is corrected by adjusting the position and / or orientation of one or more camera units relative to each other and / or relative to the projector unit.

24. The scanner system according to any one of the preceding claims, wherein, The reference marker has a predefined geometric shape selected from a group consisting of: polygonal shape, rectangular shape, triangular shape, cross shape, rhombus shape, circular shape, line shape and / or combinations thereof.

25. The scanner system according to any one of the preceding claims, wherein, The transparent window is made of glass, such as sapphire.

26. The scanner system according to any one of the preceding claims, wherein, The transparent window is made of a polymer, such as poly(methyl methacrylate) (PMMA).

27. The scanner system according to any one of the preceding claims, wherein, One or more processors are configured to continuously calibrate the intraoral scanner during use based on continuously correcting the geometric relationships.

28. The scanner system according to any one of the preceding claims, wherein, One or more processors are configured to calibrate the intraoral scanner in real time during use of the scanner.

29. A method for recalibrating an intraoral scanner, the method comprising the following steps: a. Acquire two or more sets of images, wherein, The images are acquired by individual scanning units of the intraoral scanner, each scanning unit including one or more camera units, wherein each set of images contains a reference marker pattern; b. Determine the difference between the imaging reference mark pattern and the predefined arrangement of the reference marks; c. Determine whether the geometric relationship between the scanning unit and / or the camera unit has changed based on the identified differences; and d. Based on the determined differences, correct the geometric relationships in the geometric model of the intraoral scanner, thereby recalibrating the scanner.

30. The method according to claim 29, wherein, The geometric relationship is continuously and in real time corrected.

31. The method according to any one of claims 29 to 30, wherein, The steps of the method are executed continuously and in real time.

32. The method according to any one of claims 29 to 31, wherein, The reference marker pattern is located in the window of the intraoral scanner.

33. The method according to any one of claims 29 to 32, wherein, The geometric relationship includes the orientation of each scanning unit and / or the relative orientation between the scanning units.

34. The method according to claim 33, wherein, The given orientation of the scanning unit includes the position and orientation of the scanning unit.

35. The method according to any one of claims 29 to 34, wherein, The geometric relationship includes the pose of each camera unit and / or the relative pose between the camera units.

36. The method according to claim 35, wherein, A given pose of the camera unit includes the position and orientation of the scanning unit.

37. The method of claim 34, wherein, The orientation of a given scanning unit is defined by the optical axis of a projector unit that forms part of the scanning unit.

38. The method according to any one of claims 29 to 37, wherein, The geometric relationship between the scanning unit and / or the camera unit is corrected based on the Euclidean transformation of the orientation of at least one scanning unit.

39. The method according to any one of claims 29 to 38, wherein, The geometric relationship between the camera units is corrected based on the Euclidean transformation of the pose of at least one camera unit.

40. The scanner system according to claim 39, wherein, The Euclidean transformation has at least three degrees of freedom.

41. The scanner system according to claim 39, wherein, The Euclidean transformation has at least six degrees of freedom.

42. The method according to any one of claims 29 to 41, wherein, The determined differences are selected from the group consisting of: the position of the reference mark, the size of the reference mark, the orientation of the reference mark, and / or combinations thereof.

Images