Method for determining estimate of fitting height of lens in spectacle frame, and corresponding device

Abstract

Method for determining an estimate of the fit height of a lens (11L) in a frame (10u, 10b, 17) of eyeglasses, in which an upper reference point (16) of the frame at a level above a mounting point is specified, said reference point allowing an upper reference horizontal plane (18) passing over said upper reference point (16) to be defined, and measuring a structural term (FH 'struc, FHstruc) defined as an algebraic distance between the lower reference line and the upper reference horizontal plane (18), and also measuring a posture term (FHpos) defined as an algebraic distance between the upper reference horizontal plane (18) and the gaze axis (14L), estimating a fit height (FH, FHapprox) by summing the value of the posture term and the value of the structural term. An apparatus for determining an estimate of a fitting height of a lens, the apparatus comprising a computer and a camera connected to the computer, the camera and the computer being configured to perform the method.

Description

Technical Field

[0001] The invention relates to a method for determining an estimate of the fitting height of a spectacle lens. The invention also relates to an apparatus comprising means for determining the fitting height of a spectacle lens and implementing the method.

[0002] The device allows the fitting height to be determined automatically, thanks to the use of one or more 2D or 3D cameras, and advantageously without any intervention by an eye care practitioner. This determination can also be done with the intervention of an eye care practitioner, either by measuring the wearer of the glasses directly (possibly using a measuring device requiring manual operation) or indirectly using pictures (the eye care practitioner measuring the pictures). Background Art

[0003] Eyeglasses and their lenses can be defined by multiple parameters. Figure 1 Parameters are shown above, where the indexes R and L refer to the right lens and the left lens, respectively. Reference "a*" is the horizontal dimension of the lens grid, "b*" is the vertical dimension of the lens grid, "c" is the distance between the L and R centers of the frame system, "d*" is the distance between the lenses, "CR", "CL" are the centers of the frame system for the right lens and the left lens, respectively, "1R", "1L" are the right horizontal midline and the left horizontal midline, respectively, "2R", "2L" are the right vertical midline and the left vertical midline, respectively, "3R", "3L" are the right lens plane and the left lens plane, respectively, "4R", "4L" are the angles from the lens plane to the frontal plane at the centers CR, CL of the frame system for the right lens and the left lens, respectively, "5" is the common tangent to the upper edge of the lens shape, and "6" is the frontal plane of the glasses passing at the centers CR, CL of the frame system. The horizontal and vertical directions apply because the frame of the glasses should be horizontal, i.e. its main frontal axis is horizontal, i.e. the two hinged temples are at the same level as when the wearer normally wears the glasses in a natural posture.

[0004] The frame system of the lens is defined as an imaginary frame around the lens shape, wherein the sides of the frame are tangent to the outermost edge of the lens shape. Therefore, the frame system of the lens is also defined as the vertical and horizontal sides of the frame being tangent to the outer edge of the lens. The frame system of the lens has a lower horizontal side and an upper horizontal side. The lower horizontal side of the frame system passes through the lowest point of the bottom part of the peripheral outer edge of the lens and is therefore tangent to the outer edge of the lens at this lowest point. The upper horizontal side of the frame system passes through the highest point of the upper part of the peripheral outer edge of the lens and is therefore tangent to the outer edge of the lens at this highest point.

[0005] The sides of a frame system are usually used as references for measurements. In this context, we will see that a lower reference line is usually considered and is included in the lower horizontal side of the frame system of the lens (i.e. the lower reference line is on a plane or passes on a plane). In the present invention, the word "includes" means that the length of the line can be limited to the size / length of the side of the frame system and the line can extend beyond the size / length of the side of the frame system, in all cases the side of the frame system carries the line and this applies to the upper and lower reference lines and sides of the frame system. This also means that the lower reference line is horizontal.

[0006] The determination of the fitting height of lenses in spectacles is particularly important for the optical comfort of wearers of complex lenses like progressive lenses.

[0007] Prior art Figure 2 A side view of a cross section of the eyeglasses is shown. Figure 2 In the figure, the upper part 10u of the frame and the lower part 10b of the frame can be seen, which are the parts surrounding the left lens 11. L The left mirror ring of the 12. The left temple can be seen in the background. L .

[0008] Pupil of left eye 13 L The horizontal gaze axis 14 of the eyeglass wearer, illustrated as a large dot, in a natural posture L Indicated as a dotted line, the wearer sees an object far / infinitely far ahead, with the eyes oriented straight ahead. Horizontal gaze axis 14 L At mount point 15 L The definition point is at the left lens 11 L intersect in front of .

[0009] The left lens 11 is shown L The fitting height FH and the lens plane 3 of the left lens L relationship Figure 2 In FIG. 3 , the fitting height FH is symbolized as a straight arrow. It can be noted that the value of the fitting height is the value of the fitting height vector at the lens plane 3 L The length of the orthogonal projection on the lens, the adapted height vector will be 15 L Connected to the point of the horizontal lower reference line, the fit height vector is orthogonal to the lower reference line. As usually implemented, the lower reference line is included in the lower horizontal side of the frame system of the lens and is therefore tangent to the bottom part of the peripheral outer edge of the lens at its lowest point.

[0010] The following documents relate to methods and devices for fitting lenses: US 2009 / 066914 A1, US 2020 / 183194 A1, WO 2021 / 122826 A1 and US 2015 / 049306 A1.

[0011] Currently, fit height measurement can be done manually by an eye care practitioner, or can be automated or semi-automated using a 2D or 3D camera and computer system. In some cases, an additional protocol is used to derive a value for the anterior tilt angle, which is the angle between the lens plane 3 L The angle with the vertical line. is an example of such an automated camera system.

[0012] Some of these known camera systems require intervention by an eye care practitioner to position the pupil and / or the frame system. In particular, in the case of spectacles with rimless or partially rimless frames, positioning the frame system is often difficult. Some systems also require complex protocols to estimate the anteversion angle in order to correct the height measured on the vertical plane in the picture taken by the camera and give a result corresponding to the definition of the fitting height, where the distance considered is the lens plane 3 L Projection on.

[0013] In practice, in these known camera systems, the wearer of the glasses is positioned in front of the camera. In some embodiments, a one-way mirror can hide the camera from the wearer. The camera is connected to a computer, which performs all processing in multiple stages.

[0014] Then, in a recording phase, a picture is recorded of the wearer's face wearing the spectacle frames normally (preferably with two demo lenses), the wearer looking straight ahead with a horizontal gaze axis at an object located at a distance, the wearer being in a natural posture with his / her head vertical, i.e. the frontal part of the ear-orbital plane of the wearer's head defines the horizontal line.

[0015] Then, in the center detection stage, the center of the pupil on the picture is detected by the computer for each eye. This detection can be done automatically using image processing algorithms and / or with the help of an eye care practitioner who manually points to the center of the pupil.

[0016] Then, in the frame system detection phase, a detection of the lower horizontal edge of the frame system is performed for both lenses of the eyeglasses. This allows to define a lower reference line for each lens, which is included in the lower horizontal edge of the frame system of the lens, or generally to define a common lower reference line common to both lenses. In practice, this common lower reference line tangentially connects the bottom peripheral outer edges of the two lenses at their respective lowest points. Again, this task can be done automatically and / or with the help of an eye care practitioner, this last case being preferred when the frame is rimless or has no rim bottom portion.

[0017] Then, in the calculation phase, the vertical distance between the pupil center and the lower reference line is calculated on the image.

[0018] This automated or semi-automated method has some disadvantages, as there is no correction for the anteversion angle, and it does not take into account the off-paraxial effects due to the wearer not being in front of / facing the camera. Additionally, for rimless glasses, it is almost impossible to automatically detect the frame system, in particular the lower horizontal edge of the frame system. Furthermore, in the case where there is also a correction for the anteversion angle, this is done by additional measurements on some of the previous phases that add their own inaccuracies / errors.

[0019] A method for estimating the fitting height is proposed which is much simpler while providing relatively accurate results and can be used efficiently for frameless or partially frameless eyeglass frames. This last advantage is based on the use of an upper reference point which is above the mounting point and on a part that is always present in the frame (i.e. the bridge of the nose) or in frames without a bottom part of the frame rim (i.e. using the upper part of the rim). Other advantages of the invention will become apparent from the description of the invention. Summary of the invention

[0020] It is therefore an object of the present invention to provide a method for determining an estimate of the fit height of a lens in an eyeglass frame worn by a wearer, the lens being in front of a pupil of the wearer's eye, the lens having a front face and a peripheral outer edge, the peripheral outer edge including a bottom portion of the edge, the lens plane of the lens being defined and when the frontal portion of an orbital plane of the wearer's head defines a horizontal line and the wearer sees an object located at a far distance through the pupil of the eye with the eye oriented straight ahead and a horizontal gaze axis passing through the center of the pupil, then the gaze axis of the eye intersects the front face of the lens at a defined mounting point, the fit height of the lens being defined as the length of an orthogonal projection of a fit height vector on the lens plane, the fit height vector connecting the mounting point of the lens with a point of a lower reference line, the lower reference line being horizontal and tangent to the bottom portion of the peripheral outer edge of the lens at its lowest point, the fit height vector being perpendicular to the lower reference line,

[0021] wherein an upper reference point of the frame, located at a level above the mounting point, is specified, said reference point allowing definition of an upper reference horizontal plane passing through said upper reference point,

[0022] Among them, the measurement structure term, which is defined as the algebraic distance between the lower reference line and the upper reference horizontal plane,

[0023] where a posture term is measured, which is defined as the algebraic distance between the upper reference horizontal plane and the gaze axis, and

[0024] Therein, the fitting height is estimated by summing the value of the posture term and the value of the structure term.

[0025] In different embodiments of the invention, the following processing means are used, which can be used alone or in any technically possible combination:

[0026] - the lower horizontal side of the frame system passes through the lowest point of the bottom part of the peripheral outer edge of the lens,

[0027] - a lower reference line, horizontal and tangential to the bottom portion of the peripheral outer edge of the lens, is included in the lower horizontal side of the frame system of the lens,

[0028] - a point on a lower reference line that is horizontal and tangential to the bottom portion of the peripheral outer edge of the lens is the lowest point of the bottom portion of the peripheral outer edge of the lens,

[0029] - the structural term FH'struc is the length of the orthogonal projection on the lens plane of the structural vector that connects the upper reference point with the point of the lower reference line, the structural vector being perpendicular to the lower reference line,

[0030] - Equivalently, the structural term FH'struc is the length of the orthogonal projection on the lens plane of the structural vector connecting the points of the upper reference horizontal plane with the lower reference line, the structural vector being perpendicular to the lower reference line,

[0031] - The structural term FHstruc is the vertical distance between the upper reference horizontal plane and the point of the lower reference line,

[0032] - the posture term FHpos is the vertical distance between the upper reference horizontal plane and the gaze axis,

[0033] -The angle of inclination of the lens plane compared to the vertical direction And wherein the vertical distance is further corrected for the forward tilt angle to provide a corrected posture item, the corrected posture item being The result is, and the fit height is estimated by summing the value of the corrected pose term with the value of the structure term, both of which are algebraic distances,

[0034] - the lower edge of the lens fits into the bottom part of the frame,

[0035] - the upper edge of the lens fits into the upper part of the frame,

[0036] - the wearer wears the frame in a natural posture in which the frontal part of the ear-orbital plane of the wearer's head defines a horizontal line so that the pupils are horizontal and therefore in the same horizontal plane, the glasses comprise two lenses and are worn horizontally, the two defined mounting points of the two lenses being in the same horizontal plane,

[0037] - the lens plane is the plane tangent to the lens at the center of the frame system of the lens, the center of the frame system being in the middle of the horizontal dimension of the frame system and in the middle of the vertical dimension of the frame system,

[0038] - structural items are obtained from a construction plan of the frame and are provided as data attached to the frame produced according to that plan,

[0039] - the structural items are measured once at the factory where the frames are produced and provided as data attached to the frames,

[0040] - the structural item is measured once on one frame in a batch of identical frames at the factory where the frames are produced and is provided as data attached to each frame in the batch,

[0041] - measuring structural items when at least one lens has to be prepared for a new pair of spectacles or modified or changed for an updated pair of spectacles,

[0042] - data attached to the frame is tangible information, such as values ​​printed on paper or on the frame,

[0043] - the data attached to the frame is intangible information, such as values ​​stored in an electronic memory and / or computerized system,

[0044] - the data attached to the frame is intangible information, such as a value transmitted through a computer network,

[0045] - Upper reference point is selected from:

[0046] - the point at the lower edge of the bridge of the frame,

[0047] - the highest point of the lower edge of the bridge of the frame,

[0048] - the point on the upper edge of the bridge of the frame,

[0049] - the highest point of the upper edge of the bridge of the frame,

[0050] - the point of the upper part of the frame that receives and houses the upper edge of the lens,

[0051] - the point of the lower edge of the upper part of the frame that receives and houses the upper edge of the lens,

[0052] - the highest point of the lower edge of the upper part of the frame that receives and houses the upper edge of the lens,

[0053] - a point on the upper edge of the upper part of the frame that receives and houses the upper edge of the lens,

[0054] - the highest point of the upper edge of the upper part of the frame that receives and houses the upper edge of the lens,

[0055] - a point on an upper reference horizontal line or plane which is horizontal and tangential to the upper portion of the peripheral outer edge of the lens,

[0056] - the upper horizontal side of the frame system passes through the highest point of the upper part of the peripheral outer edge of the lens,

[0057] - an upper reference horizontal line that is horizontal and tangential to the upper portion of the peripheral outer edge of the lens is included in the upper horizontal side of the frame system of the lens

[0058] - a point on an upper reference horizontal line that is horizontal and tangential to the upper portion of the peripheral outer edge of the lens is the highest point of the upper portion of the peripheral outer edge of the lens,

[0059] - when considering the two lenses of the spectacles, each reference point on the upper part of the frame is at the same respective level in the reference horizontal plane,

[0060] - The bridge of the frame is designed to fit around the upper part of the wearer's nose,

[0061] - the structural item is measured once on a frame with or without fitted lenses and provided as data attached to the frame and preferably also to other identical frames,

[0062] - the structural item is measured by a computerized device using one or more pictures taken by a 2D or 3D camera,

[0063] - Posture items are measured manually,

[0064] - the posture item is measured by a computerized device using one or more pictures taken by a 2D or 3D camera,

[0065] - the picture obtained with the computerized device is clearly in a vertical plane and facing the glasses,

[0066] -the computerized device and the 2D or 3D camera are located at the same location,

[0067] - the computerized device and the 2D or 3D camera are not located at the same place and are elements of a network, in particular the Internet, the picture being taken remotely from the computerized device,

[0068] -The computerized device is a smartphone,

[0069] -The computerized device is a computer connected to a 2D or 3D camera,

[0070] - a computerized device is a device comprising a computing circuit, a 2D or 3D camera and a human-machine interface,

[0071] -Computerized equipment is programmable.

[0072] - the computerized device using the pictures is configured to reject pictures taken by a 2D or 3D camera when the pictures obtained are not in a vertical plane and facing the glasses,

[0073] - the computerized device using the pictures is configured to reject a picture taken by a 2D or 3D camera when in the obtained picture: the face of the wearer cannot be detected and / or the frames cannot be detected on the face of the wearer and / or an error in face detection due to a bad position of the wearer is produced and / or an error in frame detection due to reflections or shadows on the lenses is produced and / or a detection that the wearer is too close or too far from the camera is produced and / or a detection that the frames are not worn correctly is produced and / or the pupil is not detected, in particular due to eye blinking,

[0074] - the computerized device using the picture is configured to correct the picture taken by the 2D or 3D camera when the picture obtained is not in a vertical plane and is facing the glasses,

[0075] - The pictures are corrected by computerized equipment using mathematical and image processing,

[0076] - the inclination of the wearer's head in the picture is corrected by detecting the tangents of the frame system of the lenses, which are then taken into account in the calculation,

[0077] - detect head orientation using facial landmarks detected by machine learning techniques,

[0078] - the computerized device using the pictures is configured to reject pictures taken by the 2D or 3D camera when the wearer wearing the frames is not in a natural posture or when the wearer's head is not upright, and / or when the glasses are not worn horizontally, and / or when the wearer is not looking at an object located far ahead / infinity, and / or when the eyes are not oriented straight ahead with a horizontal gaze axis,

[0079] - the computerized device using the pictures is configured to correct the pictures taken by the 2D or 3D camera when the wearer wearing the frames is not in a natural posture and / or when the wearer's head is not upright and / or when the glasses are not worn horizontally and / or when the wearer is not looking at an object located far in front / infinity,

[0080] - the computerized device is configured to perform correction calculations (i.e., calculus) when the wearer of the frames is not in a natural posture and / or when the wearer's head is not upright and / or when the glasses are not worn horizontally and / or when the wearer is not looking at an object located far ahead / infinity,

[0081] - a computerized device detects, on at least one image of the wearer, an upper reference point or an upper reference horizontal plane and a pupil center of at least one of the two eyes and calculates (i.e. computes) a posture term and then estimates the fit height by summing the value of the posture term with the value of the structure term, both terms being algebraic distances,

[0082] - a computerized device iteratively detects the pupil center and the upper reference point on a set of images of the wearer and then calculates a posture term at each iteration,

[0083] - a computerized device iteratively detects an upper reference point or an upper reference horizontal plane and a pupil center of at least one of the two eyes on each image of a set of images, and then calculates a set of posture items, and wherein a statistical calculation is applied to the set of posture items, wherein an upper confidence limit and a lower confidence limit consisting of two posture distance values ​​are calculated (i.e., calculated), posture items with values ​​greater than the upper confidence limit and posture items with values ​​less than the lower confidence limit are deleted, and the remaining posture items are averaged, and wherein the fitting height is estimated by summing the value of the average posture item with the value of the structure item, both of which are algebraic distances,

[0084] - before the pictures are taken, the wearer wearing the frames is instructed to assume a natural posture in which the frontal portion of the ear-orbital plane of the wearer's head defines a horizontal line and is instructed to wear the glasses normally,

[0085] - The wearer is instructed to wear the glasses horizontally,

[0086] - For each of the wearer's two eyes, an estimate of the fit height is made.

[0087] Another object of the present invention is to provide a device for determining an estimate of the fit height of a lens in an eyeglass frame worn by a wearer, wherein the device comprises a computer and a camera connected to the computer, and wherein the camera and the computer are configured to perform the method of the present invention.

[0088] The invention will now be illustrated, without being limited, by the following description of examples and embodiments with reference to the following drawings:

[0089] Prior art Figure 1 shows the parameters defining the characteristics of an eyeglass frame and its lenses,

[0090] Prior art Figure 2 A side view of a cross section of the eyeglasses in relation to the pupil of the eye of a wearer who normally wears the eyeglasses and is in a natural posture and looking straight ahead at an object far in front is shown, as well as the way in which the mounting point and the fitting height are generally defined,

[0091] Figure 3 A front view of an eyeglass frame with lenses in relation to the eyes of a wearer wearing the glasses normally and in a natural posture and looking straight ahead at an object far ahead is shown, as well as the distances measured in an embodiment of the invention,

[0092] Figure 4 Shows Figure 3 , and other distances measured in another embodiment of the present invention,

[0093] Figure 5 A flowchart showing an example of a procedural implementation of the present invention is shown,

[0094] Figure 6 A front view of an eyeglass frame with lenses is shown with some examples of upper reference points.

[0095] In the relevant figures, the fitting height FH is symbolized as a straight arrow. The structural term FH'struc resulting from the projection of the structural vector on the lens plane is symbolized as a straight arrow. The vertical approximate fitting height FHappox is symbolized as a straight arrow. The structural term FHstruc, which is vertical and resulting from the projection of the structural vector on the vertical plane, is symbolized as a straight arrow. The posture term FHpos, which is vertical and resulting from the projection of the posture vector on the vertical plane, is symbolized as a straight arrow. DETAILED DESCRIPTION

[0096] The principle of the invention is based on adapting the decomposition of the height in two terms: a structural term and a posture term.

[0097] Structural items are distances which can be measured precisely and advantageously only once, preferably at the factory where the frame is manufactured. The structural items depend only on the spectacle frame. In fact, the structural items depend only on the geometry / structure of the frame and not on the way the frame is worn. The presence of the (future) wearer of the spectacle frame is not required to measure the structural items. Advantageously, the acquisition of the structural items, in particular by measurement, can be done by the manufacturer of the spectacle frame and the structural items can, for example, be stored in a database for later use or engraved on the frame. In some cases, the measurement of the structural items can be done by an eye care practitioner in a shop, for example when he receives the frame and uses a computer with which he has been trained. The device is completed by a similar device.

[0098] The posture item needs to be measured by manual measurement or fully or partially automated measurement of a wearer of the eyeglass frames wearing the eyeglass frames without or preferably with demonstration lenses. In practice, the posture item depends on the way the frames are normally worn in a natural posture during a distance vision task. The posture item can advantageously be measured with a computerized device and using a simple 2D camera or using a 3D camera for more precise measurements. The computerized device analyzes the obtained frontal picture of the face of the wearer wearing the eyeglass frames, the frontal part of his / her ear-orbital plane defining the horizontal line, the wearer being in a natural posture and looking straight ahead at an object located far ahead.

[0099] The posture term is a shorter distance than the structure term.

[0100] The structure term is added to the posture term to give an estimate of the fit height, which gives a resulting value that is less than the value of the structure term due to considering the structure and posture vectors pointing in opposite directions and considering the algebraic distances associated with the vectors.

[0101] The fact that the posture term is much smaller than the structural term and that the structural term can be obtained / measured accurately gives the advantage that the effect of errors in the posture term on the accuracy of the fitted height is reduced. Furthermore, we will see that an estimate that actually corresponds to the definition of the fitted height can be determined by a correction of the posture term for the forward tilt angle.

[0102] More generally, the posture term can be viewed as a correction term that allows avoiding frameless frames or The measurement difficulties encountered with eyeglass frames, or the use of 2D cameras in known camera systems, minimize or suppress the effects of anteversion angle measurement errors or non-paraxial effects. In addition, the use of structural items that can be accurately obtained independently of the wearer avoids the necessity to find the 3D position of the lower horizontal edge of the frame system, which position is particularly difficult to accurately detect with conventional 2D or 3D cameras in known camera systems.

[0103] For frameless frames or The provided configuration is based on the demo lens used by the eye care professional (ECP) in the store, and if the eye care professional eventually wants to order another type of lens than the demo lens, he must provide the value b* / 2 (i.e. the vertical dimension from the lens frame, see Figure 1 ) between the two.

[0104] The reference point for measuring posture and structural items is not at a level (i.e. height) below the pupil level, but at a level above the pupil level, which is why it is called the upper reference point. The upper reference point of the invention can be located on the frame of the glasses, or can be a point on the upper horizontal edge of the frame system or a point on the upper reference horizontal line included in the upper horizontal edge of the frame system. Thus, in the case where the frame is completely or partially frameless, i.e. the upper part of the rim is not present in the frame, if no upper reference point is chosen on the bridge of the nose portion of the frame that is always present, an upper reference point on the upper edge of the lens and preferably on the upper horizontal edge of the frame system can be used.

[0105] Since the purpose of the invention is to estimate the fitting height, a lower reference line identical to the definition of the fitting height is used. This lower reference line allows the determination of the structure term as we will see, ie it determines the bottom of the structure vector.

[0106] Preferably, the upper reference point 16 for measuring posture and structure items is the highest point of the bottom edge of the nose bridge 17, such as Figure 3 and Figure 4 The nose bridge 17 is the portion of the frame that is arranged around the wearer's nose.

[0107] Figure 6 Other upper reference points that may be used are shown as examples:

[0108] - the highest point 16 of the lower edge of the bridge 17 of the frame,

[0109] - the highest point 16a of the upper edge of the bridge 17 of the frame,

[0110] - point 16b of the upper part 10u of the frame,

[0111] - point 16c of the lower edge of the upper part 10u of the frame,

[0112] - the highest point 16d of the lower edge of the upper part 10u of the frame,

[0113] - a point 16e of the upper edge of the upper part 10u of the frame,

[0114] - the highest point 16f of the upper edge of the upper part 10u of the frame,

[0115] - A point 16g on an upper reference horizontal line or plane which is horizontal and tangential to the upper portion of the peripheral outer edge of the lens.

[0116] For the measurement of posture items, the mounting point 15 is also used L For measurements of structural items, the lower reference line is also used, as it is used to measure the fitting height in a known camera system.

[0117] The upper reference point 16 and the lower reference line allow to define a structural vector orthogonal to the lower reference line. The structural vector under consideration extends between a point on the lower reference line at its lower end and the upper reference point 16 at its upper end, to which it is orthogonal, the lower reference line being horizontal. The structural vector is therefore contained in a vertical plane. The structural vector points to the top.

[0118] In practice, the lower reference line is included in the lower horizontal edge of the frame system. More generally, the lower ends of the fit height (or another name in case the lower reference line is modified) vector and the structure vector can be defined on a lower reference line that is modified and does not refer to the frame system (e.g., a lower reference line that passes through a specific point of the bottom part of the bezel of the frame). In all cases, the lower ends of the fit height vector and the structure vector must be defined in the same way, i.e., on the same lower reference line.

[0119] Mounting point 15 L and the upper reference point 16 allow the definition of the posture vector. The posture vector under consideration has the mounting point 15 at its lower end L and a point at the level of the upper reference point 16 at its upper end, these two points make the posture vector contained in the vertical plane. One or both ends of the posture vector can also be respectively passed through the mounting point 15 Land one or two horizontal lines and / or planes defined by the upper reference point 16. The posture vector points to the bottom.

[0120] Figure 3 Schematically corresponds to a 2D picture taken by a 2D camera of the wearer's face in a natural pose and seeing an object located far in front / infinity, with the eyes oriented straight ahead. With a 3D camera, additional depth information can be obtained (i.e. in the direction away from the camera) and pictures of slices of the 3D scene in the depth direction (i.e. frontal slices) can be constructed, for example, or pictures from different perspectives and preferably lateral views to visualize the anteroposterior angle. The anteroposterior angle can be estimated with a 2D camera in a lateral position of the wearer's head, so with two 2D cameras (one in front of the wearer to get the wearer's face and the other in a lateral position), accurate results can be obtained without using a 3D camera.

[0121] Figure 3 An embodiment of the invention will now be described which is simple since the distances considered for posture and structural items are in the vertical plane and therefore these distances can be measured directly on a 2D picture of the wearer's face. Figure 3 This simple embodiment of produces an approximate adaptation height FHapprox also in the vertical plane.

[0122] exist Figure 3 In FIG. 1 , the distances FHpos, FHstruc, which are symbolized as straight arrows, are measured in the vertical plane of the picture. The distance FHpos is a posture term and is the distance between the upper reference horizontal line or plane 18 ( Figure 4 ) passes through the center of the pupil 13L and is aligned with the horizontal gaze axis 14 L ( Figure 4 ) are measured vertically between horizontal lines or planes at the same level. In practice, due to the wearer's posture and gaze direction, the pupil center on the image corresponds to the mounting point 15 L .

[0123] In this simple embodiment, the distance FHstruc is a structural term and is the distance between the lower reference line and the upper reference point 16 (or the upper reference horizontal line or plane 18 passing through the upper reference point 16 ( Figure 4 )) and it is the vertical distance. An estimate of the value of the fitting height FHapprox can be obtained by the following calculation: FHapprox = FHstruc + FHpos, these last two values ​​being the algebraic distances.

[0124] In fact, in this simple embodiment of the invention, the structure vector and the posture vector are projected on a vertical plane which actually corresponds to the picture plane, and the resulting approximate fitting height FHappox is therefore in the vertical plane.

[0125] In this simple embodiment, all terms are obtained directly from the 2D picture and are in the vertical plane without any correction for forward tilt or projection in the lens plane.

[0126] We will see that a more accurate estimate of the fit height can be obtained using a more accurate structural term that uses the projection of the structural vector onto the lens plane, and also with a correction for the posture term for the anteversion angle or the projection of the posture vector in the lens plane.

[0127] In fact, in addition to the fact that the posture term is smaller than the structural term, another advantage of using an upper reference point above pupil level is that it is also possible to use a reference point along the pupil level when, for example, Figure 4 When viewed in the side view of the lateral view, the vertical line intersecting the lower reference line at the lower end of the adapted height vector is closer to the mounting point 15. L The different spacings between these vertical lines are related in particular to the anteversion angle and therefore to the inclination of the lens plane. Therefore, the measurement of distances for posture items (performed from a 2D view or picture and where the posture items are only vertical distances) is less distorted when considering the definition of the fitting height, which is the distance in the lens plane rather than in the vertical plane.

[0128] Now, about Figure 4 , where lens plane 3 L It is visible that a more precise embodiment of the invention is described. In this embodiment, the projection of the structure vector on the lens plane is used. In practice, a structure term FH'struc can be obtained, the structure vector being projected on the lens plane or on a plane parallel to the lens plane, especially in the case where the measurement is substantially done with a ruler.

[0129] In a more precise embodiment of the present invention, the structural vector is projected on the lens plane to obtain a distance corresponding to the structural term FH'struc. Therefore, the structural term FH'struc is closer to the definition of the fitting height because they are both in the lens plane. The fitting height is calculated by adding the posture term FHpos and the structural term FH'struc: Fitting height = FH'struc + FHpos, and the value of the fitting height thus obtained is closer to the defined fitting height FH.

[0130] Incidentally, the structural item FH'struc may be named "angled structural item" to distinguish it from the structural item FHstruc which may be named "vertical structural item".

[0131] However, in this more precise embodiment, the posture term FHpos used is still the vertical distance, i.e. the posture vector projected on the vertical plane. Therefore, the accuracy of the fitting height calculated by the correction of the posture term for the forward tilt angle or the projection of the posture vector on the lens plane can also be improved.

[0132] In the operations performed in the present invention, the distances between points can be determined, in particular, a point on the lower reference line and an upper reference point for a structure item, or a point corresponding to the pupil center and an upper reference point for a posture item. In practice, the posture vector and the structure vector defining the measured distance are each defined by their respective two ends (the lower end, such as a point on the lower reference line, and the upper end, such as an upper reference point). The same is true for the adaptation height vector. It should be noted that these vectors have specific directions, with the adaptation height vector pointing to the top, the structure vector pointing to the top, and the posture vector pointing to the bottom.

[0133] However, it is also possible to determine the distance between a point and a horizontal line or between a point and a horizontal plane or between a horizontal line and a horizontal plane. Non-limiting examples of usable horizontal lines are a horizontal line passing through a reference point or pupil center, a lower horizontal edge of a frame system, an upper horizontal edge of a frame system. Non-limiting examples of usable horizontal planes are a horizontal plane passing through a reference point or pupil center, a horizontal plane supporting a reference line or gaze axis (i.e., the line or axis is on a plane). In addition, in order to consider only one eye at a time, it is also possible to consider two eyes and / or two bezels and lenses for defining common reference lines and planes, for example, a horizontal plane passing through two centers of two pupils, a horizontal plane passing through two gaze axes of two eyes, a horizontal plane passing through two lower horizontal edges of two frame systems of two lenses. Examples of common horizontal lines and corresponding horizontal planes defined in the picture are a horizontal line crossing the two pupil centers or two gaze axes of the two eyes (used to define the bottom end of the posture vector), a horizontal line connecting the two lower horizontal edges of the two frame systems of the two lenses (used for a common lower reference line or plane), and a horizontal line connecting the two upper horizontal edges of the two frame systems of the two lenses (used for a common upper reference horizontal line or plane 18).

[0134] With regard to the characteristic "horizontal" of lines and planes (and correspondingly vertical lines and planes), this is firstly to simplify the description of the invention (in particular to help reference in space to the corresponding positions and orientations of these elements of the invention), and secondly, this is related to the fact that, for the measurement, the glasses should be worn normally by the wearer in a natural posture, in which the frame is horizontal and the two pupil centers are on a horizontal line or plane. More generally, this also means that these lines and planes used to measure the distance (i.e., the ends defining the posture vector and the structure vector) are parallel to each other. This corresponds to the most commonly encountered ideal situation. However, the invention is also applicable to cases that deviate from those ideal situations due to calculations (i.e., calculations) that take into account deviations from the ideal situation. For example, the fact that the frame is tilted on one side (resulting in the frontal part of the ear-orbital plane defining a non-horizontal line) can be taken into account in the calculation. The fact that the gaze direction is not horizontal can be taken into account, for example, due to a complementary system that allows to estimate the gaze direction (i.e., eye tracking) and take it into account in the calculation. Deviations can be taken into account by image processing, for example by rotation of the taken image(s).

[0135] Thus, since the camera is configured to provide a picture in which the horizontal line of the rendered scene is the horizontal line of the pixels in the picture, the distances between lines defined in the picture and that are horizontal can be determined and / or the distances between planes defined in the picture and that are horizontal can be determined (the picture may have been corrected to make the lines and / or planes horizontal, or the calculation takes into account the tilt of the lines and / or planes). It may be noted that some image processing may be applied to correct for some defaults in the head position and / or frame fit, such as rotating the picture to correct for a slight tilt of the wearer's head.

[0136] The detection of reference points or lines or planes can be done using standard image processing techniques such as face localization, facial landmark localization, edge detection... or using machine learning algorithms such as convolutional neural networks... to find the frames in the picture. The measurements obtained from the picture also use known mathematical procedures in order to be able to convert the pixel size of the object on the picture to the real size of the object in the real world.

[0137] For rimless frames, embodiments of the present invention are much easier than known systems, since the detection of the upper reference point or line or plane is much easier since points of the nose bridge portion of the frame can be used, and there is no need to detect the frame system, since the structural items are obtained in advance and can be measured exactly once. For known systems, additional devices (such as IR cameras or addiction light systems) must be used to be able to detect the frame system of rimless frames.

[0138] Figure 5 A flow chart of an example of a procedural implementation of the present invention is shown in FIG. 1 , wherein numbers 0 to 9 refer to steps of the operation.

[0139] In step 0, the structural items are measured. In this example, the structural items are obtained from the FH'struc parameters. Such measurements can be done once at the factory where the eyeglass frames are manufactured, and the structural items are therefore obtained from information / data provided by the manufacturer (e.g. extracted from a frame database). When such information / data is not available, the structural items can be measured using means commonly used for this purpose, and for example A device that uses the lens plane and provides results according to the description provided above for the FH'struc parameter.

[0140] In step 1, the wearer is instructed to wear the glasses normally and in a natural posture, in which the frontal part of the ear-orbital plane of the wearer's head defines a horizontal line. He / she is also instructed to look at an object located at a distance, with the eyes oriented straight ahead towards a device configured to perform a method according to the invention for providing a fitting height for each lens or two lenses as the case may be. The device comprises a computer device and a camera inserted thereon, the camera being at least a 2D camera. The camera is arranged to obtain a frontal picture of the wearer's face. The camera may be hidden from the wearer due to a one-way reflector.

[0141] In step 2, the device records a picture or video, ie a set of pictures. Thus, the wearer's face with at least his / her eyes, nose and glasses frames is on the picture as a 2D representation of the wearer's face looking straight ahead.

[0142] In step 3, the computer means of the device detects the center of each pupil of both eyes in the image using an image processing algorithm. In some cases, an eye care professional (ECP) may have to intervene by manually pointing to the center of the pupil, either only for verification of the detection and / or for manual correction of the detection.

[0143] In step 4, the computer means of the apparatus detects in the image an upper reference point 16 or an upper reference horizontal plane 18 corresponding to an upper reference horizontal line in the 2D image.

[0144] In step 5, the computer means of the device calculates a posture term based on the vertical distance / height between the level of the pupil center and the level of the upper reference point of each eye. Steps 3, 4 and 5 are iterated on each image in a set of images, and this is why in Figure 5The arrow 6 of the iterative step is represented above. In other embodiments, this is the iterative steps 2, 3, 4 and 5. The number of iterations may or may not be a predetermined value N. Of course, if the device is configured to operate on one picture, there is no iteration. In an advanced embodiment, a quality parameter is attached to each detection, and in case of low overall quality, the number of iterations is increased, and vice versa. The difference in the values ​​of the two posture items of the two eyes is an example of such a quality parameter, a high difference is likely due to an error. When the iteration of step 6 ends, the computer device of the device has a set of posture items FHpos. The posture items are items from the vertical distance / height, or step 5 can be further processed with a correction for the forward tilt angle when the angle is known (for example, manually entered into the computer device or downloaded from a database) or has been obtained by the device from an image (especially with a 3D camera) and / or with an additional device.

[0145] In step 7, the computer means of the device processes the group of posture items FHpos with statistical tools to reduce uncertainty. In the proposed example, an upper confidence limit and a lower confidence limit consisting of two values ​​of the posture distance are calculated from the group of posture items. Posture items with values ​​greater than the upper confidence limit and posture items with values ​​less than the lower confidence limit are deleted from the group.

[0146] In step 8, the computer device of the apparatus averages the remaining posture items to obtain an average value of the remaining posture items.

[0147] Finally, in step 9, the fit height is estimated by adding the average of the remaining posture terms to the value of the structure term.

[0148] In an advanced embodiment, the computer means of the device is configured to detect anomalies from the picture and correct the anomalies if possible or reject the picture and use another one. For example, in step 2, if the face or glasses cannot be roughly detected in the image, the image is rejected. For example, in step 3, if the centers of the pupils are not at the same level and the level difference is too high, this may mean that the wearer's head is tilted on one side and an attempt can be made to rotate the image. For example, in step 4, if two upper reference points on the two upper parts of the two rims are detected and are not at the same level and the level difference is too high, this may mean that the wearer's head is tilted on one side or the glasses are not worn correctly and an attempt can be made to correct the image. For example, in step 4, if the two position items of the two lenses are not equal but the difference is small, the average values ​​of the two position items can be averaged.

[0149] As an implementation example for detecting anomalies in pictures / images (e.g., non-horizontal frame orientation or poor head positioning) and / or for determining devices / parameters used in the method of the present invention, the following image processing procedure may be used.

[0150] For frame orientation:

[0151] - For example, using convolutional neural networks to detect facial landmarks in pictures / images in order to locate the eye region,

[0152] - typically using edge detection below each eye zone defined by the iris position to detect the bottom of each half frame,

[0153] - search for a line connecting two points of the two bottoms of the frame, so that all other points of the frame are above this line (i.e. the "lower line of the tangent to the frame"),

[0154] - In most cases, this alignment is horizontal (i.e. the frame is worn normally). If this is not the case and the angle of the frame orientation compared to the horizontal is smaller than a determined value, this fact is taken into account in the method in order to obtain an exact correlation by correction. If the angle is greater than the determined value, the picture / image is discarded and the procedures are repeated with a new picture / image, which may have been obtained after issuing a repeat instruction to the wearer.

[0155] For detection of poor head positioning, a procedure can be used, for example, to estimate the "right / left orientation of the head". This can be done according to the following procedure:

[0156] - For example, using convolutional neural networks to detect facial landmarks in pictures / images in order to locate the eye region,

[0157] - For example, using convolutional neural networks or more traditional algorithms (like Daugman algorithm) to detect the center of the iris of both eyes,

[0158] - calculate the two horizontal distances between the root of the nose and the two iris centers,

[0159] - In most cases, these two horizontal distances are equal or differ by less than a threshold (i.e., the head has not rotated significantly on one side). If the absolute value of these two distances differ by more than a threshold, the picture / image is discarded and the procedures are repeated with a new picture / image, which may be obtained after (again) asking the wearer to actually stand in front of the camera.

[0160] Additionally, structural items can be checked for consistency, especially when they must be measured by the device or an eye care professional or even entered by an eye care professional based on external information / data, e.g. when the input value is too far from a conventional value, a warning is issued on the device's human-machine interface.

[0161] To the wearer and the eye care professional, the operation of deriving the fit height looks very similar to that performed with known camera systems that directly measure the fit height. A difference may be that the eye care professional has to enter or measure a structural item, but this will be very rare as this structural item will usually be provided by the manufacturer of the eyeglass frame.

[0162] The invention may be implemented in many other ways without departing from the scope of the claims. For example, a possible common upper reference horizontal line or plane 18 may be a line at the top of the lens, which line may be derived from the top of the frame line by image processing. In this case, the structural term would be Figure 1 The B* size of the frame shown, and the posture term will be the distance / height between the lines passing at the center of the pupil and at the top of the upper part of the rim housing the outer edge of the lens or, better, at the top of the groove of the upper part of the rim, these lines being at least parallel or, better, horizontal. The advantage of this last case is that the B* size of the frame is an initially known quantity that has been measured and provided by the frame manufacturer.

Claims

1. A method for determining the position of a lens (110 in a frame (10u, 10b, 17) of spectacles worn by a wearer L ) is a method for estimating the fitting height of a lens, wherein the lens is fitted at the pupil (13 L ) in front of the lens, the lens having a front face and a peripheral outer edge, the peripheral outer edge including a bottom portion of the edge, the lens plane (3 L ) is defined, and when the frontal portion of the ear-orbital plane of the wearer's head defines a horizontal line and the wearer is in the eye-oriented position with the eye oriented straight ahead and with the horizontal gaze axis (14 L ) passes through the pupil (13 L ) in the center of the state through the eye (13 L ) sees an object at a distance, then the eye's gaze axis (14 L ) at the defined mount point (15 L ) and the lens (11 L ), The fitting height of the lens is defined as the fitting height vector on the lens plane (3 L ) on the orthogonal projection, the adapted height vector is the mounting point of the lens (15 L ) is connected to a point of a lower reference line, the lower reference line being horizontal and tangent to the bottom portion at the lowest point of the bottom portion of the peripheral outer edge of the lens, the fitting height vector being perpendicular to the lower reference line, It is characterized in that an upper reference point (16) of the frame, located at a level above the mounting point, is specified, the reference point allowing definition of an upper reference horizontal plane (18) passing through the upper reference point (16), and The method comprises the following steps: measuring a structural term (FH'struc, FHstruc), said structural term being defined as the algebraic distance between said lower reference line and said upper reference horizontal plane (18), A posture term (FHpos) is measured, wherein the posture term is defined as the distance between the upper reference horizontal plane (18) and the gaze axis (14 L ), and The fit height (FH, FHapprox) is estimated by summing the value of the posture term and the value of the structure term.

2. The method according to claim 1, wherein: The structural term (FH'struc) is the structural vector in the lens plane (3 L ), the structure vector connects the upper reference point (16) with the point of the lower reference line, and the structure vector is perpendicular to the lower reference line.

3. The method according to claim 1, wherein: The structural term (FHstruc) is the vertical distance between the upper reference horizontal plane (18) and a point on the lower reference line.

4. The method according to any one of claims 1 to 3, wherein: The posture term (FHpos) is the distance between the upper reference horizontal plane (18) and the gaze axis (14 L ) is the vertical distance between the 5. The method according to claim 4, wherein: The lens plane (3 L ) is tilted forward by an angle compared to the vertical direction And wherein the vertical distance is further corrected for the forward tilt angle to provide a corrected posture item, the corrected posture item is and wherein the method comprises the step of estimating the fit height by summing the value of the corrected posture term with the value of the structure term, both terms being algebraic distances.

6. The method according to any one of claims 1 to 5, wherein: The upper reference point is selected from: - the point of the lower edge of the bridge of the nose (17) of the frame, - the highest point (16) of the lower edge of the nose bridge (17) of the frame, - the point of the upper edge of the bridge of the nose (17) of the frame, - the highest point (16a) of the upper edge of the nose bridge (17) of the frame, - a point (16b) of the upper part (10u) of the frame that receives and houses the upper edge of the lens, - a point (16c) of the lower edge of the upper part (10u) of the frame that receives and houses the upper edge of the lens, - the highest point (16d) of the lower edge of the upper part (10u) of the frame that receives and houses the upper edge of the lens, - a point (16e) of the upper edge of the upper part (10u) of the frame that receives and houses the upper edge of the lens, - the highest point (16f) of the upper edge of the upper part (10u) of the frame that receives and houses the upper edge of the lens, - a point (16g) on ​​an upper reference horizontal line or plane which is horizontal and tangential to the upper portion of the peripheral outer edge of the lens.

7. The method according to any one of claims 1 to 6, wherein: The method comprises the steps of measuring the structural items (FH'struc, FHstruc) once on the frame with or without fitted lenses and providing the structural items (FH'struc, FHstruc) as data attached to the frame and preferably also to other identical frames.

8. The method according to any one of claims 1 to 7, wherein: The method comprises the step of measuring, by a computerized device, the structural item (FH'struc, FHstruc) using one or more pictures taken by a 2D or 3D camera.

9. The method according to any one of claims 1 to 8, wherein: The method comprises the step of manually measuring the posture item (FHpos).

10. The method according to any one of claims 1 to 8, wherein: The method comprises the step of measuring, by a computerized device, the posture item (FHpos) using one or more pictures taken by a 2D or 3D camera.

11. The method according to claim 10, wherein: The computerized device detects the upper reference point (16) or the upper reference horizontal plane (18) and the pupil center of at least one of the two eyes on at least one picture of the wearer and calculates the posture term and then estimates the fit height by summing the value of the posture term with the value of the structure term, both terms being algebraic distances.

12. The method according to claim 10, wherein: The computerized device iteratively detects the upper reference point (16) or the upper reference horizontal plane (18) and the pupil center of at least one of the two eyes on each picture in a set of pictures, and then calculates a set of posture terms, and wherein a statistical calculation is applied to the group of posture items, wherein an upper confidence limit and a lower confidence limit consisting of two posture distance values ​​are calculated, those posture items having values ​​greater than the upper confidence limit and those posture items having values ​​less than the lower confidence limit are deleted, and the remaining posture items are averaged, and Therein, the fit height is estimated by summing the value of the average posture term and the value of the structure term, both of which are algebraic distances.

13. The method according to any one of claims 10 to 12, wherein: Prior to taking one or more pictures, the wearer wearing the frames is instructed to be in a natural posture in which a frontal portion of an orbital plane of the wearer's head defines a horizontal line and is instructed to wear the glasses normally.

14. The method according to any one of claims 1 to 13, wherein: For each of the wearer's two eyes, an estimate of the fit height is made.

15. The method according to any one of claims 1 to 14, wherein: The computerized device using one or more pictures is configured to correct the one or more pictures taken by the 2D or 3D camera and / or correction calculations when the wearer wearing the frames is not in a natural posture and / or when the wearer's head is not upright, and / or when the glasses are not worn horizontally, and / or when the wearer is not seeing objects located far ahead / infinity.

16. A lens (110) in a frame (10u, 10b, 17) of spectacles to be worn by a wearer. L ) of the apparatus for estimating the height of the adaptation, wherein The device comprises a computer and a camera connected to the computer, and wherein the camera and the computer are configured to perform the method of any one of claims 1 to 15.

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