EP3440501A1 - Method and device for determining parameters for spectacle fitting - Google Patents

Abstract

Methods and devices are disclosed for determining parameters for spectacle fitting, particularly centering parameters. A depth information detection device (12) detects an item of depth information relating to a user's head (10), said depth information including a distance (14) from the head (10) to the device (12), (13). On the basis of this depth information and, if applicable, additional information such as images, an evaluation device (13) can then determine the desired parameters for fitting the spectacles, such as centering parameters.

Description

 Description Method and device for determining parameters for adjusting glasses

The present application relates to methods and apparatus for determining

Parameters for fitting a pair of spectacles to a person's head, in particular the

Determination of centering parameters. Such centering parameters are used to

To properly arrange spectacle lenses in a spectacle frame, that is to center, so that the spectacle lenses are worn in the correct position relative to the eyes of the person.

A generic device and a generic method are known for example from EP 1 844 363 B2.

In the approach used in this document, a pair of

Image capture devices are used to generate stereo image data from a person's head or parts of the head. From the stereo image data, a three-dimensional model of the head is then calculated. Based on the three-dimensional model, desired optical parameters can be determined. A corresponding method is also described. Instead of the pair of image recording devices, a pattern projection can also be used in a variant described in this document as an alternative.

In the device of EP 1 844 363 B2, the person to be examined is positioned in front of the device and the image recording devices then take corresponding images of the head or parts thereof. This can lead to inaccuracies in the positioning of the person, i. the person may be positioned differently from a desired nominal position, in particular a desired nominal distance. This can make it difficult to determine accurate dimensions from the images taken with the image pickup devices needed to determine the parameters. In addition, it requires the approach of EP 1 844 363 B2, in image pairs derived from the pair of

Imaging facilities are recorded, corresponding points or

To find image areas. Depending on lighting conditions, it may be difficult to do so for a sufficient number of pixels. From US 2015/323310 A1 methods and devices are known in which a pupil distance and a scale are determined using a distance measurement. A determination of spectacle fitting parameters is not dealt with in this document.

From the post-published DE 10 2005 001 874 A1 are a method and a

corresponding device for the determination of parameters for adjusting glasses known, in which with a measuring device depth information with respect to a head of a

User is detected, wherein the measuring device determines the distance of at least one eye to an image pickup device of the measuring device. A parameter of

 Use position of a pair of glasses or spectacle frame is then determined taking into account the determined distance.

US 2010/0220285 A1 discloses a method for determining parameters for

Eyewear adaptation, in particular a pupillary distance, known, in which a distance of a device used to a patient is measured and the pupillary distance is measured on the basis of the distance over a scale.

DE 689 28 825 T2 shows a reflection of a lighting on an optical axis of a camera.

A light field camera is disclosed in DE 10 2014 108 353 A1.

It is therefore an object of the present invention to provide methods and apparatus

to provide an accuracy of the determination of parameters for

 Eyeglass adjustment, especially with inaccurate positioning of a person to be examined as mentioned above, is improved.

For this purpose, a method according to claim 1 or 14 and a device according to claim 9 are provided. The subclaims define further embodiments.

According to a first and second aspect, there is provided a method of determining parameters for adjusting glasses, comprising: acquiring depth information regarding a head of a user, the depth information including a distance between the head of the user and a device used for detecting, and determining parameters for spectacle fitting based on the depth information. The depth information can Also, several distances between the head and the device at different locations of the head, which are detected at the same time or at different times include.

In addition, in the first aspect, a 2D image (hereinafter also simply referred to as an image) of the head is taken, wherein the taking of the 2D image and the detection of the

Depth information on a common optical axis takes place.

In the context of the present application, eyeglass adaptation generally refers to an adaptation of spectacles to a specific person, in particular to the person's head. Such an eyewear adaptation can, for example, begin with the selection of a specific type of eyeglass frame, in particular a specific make of eyeglass frame. An expert, such as an optometrist, will usually check to see if the eyeglass frame matches the person's anatomy (e.g., size of the frame, width of the bridge of the nose, strap length). Subsequently, the seat of the socket is checked (e.g.

Adaptation of nose pads, adjustment of the brackets to the face geometry). Finally, various parameters are measured, e.g. Pupil distance, corneal vertex distance, pre-tilt of the socket, frame disc angle, viewing height. This measurement of the above-mentioned various parameters is called Zentriermessung or

Eyeglass centering called. Some of the measured parameters affect the lens power, e.g. the corneal vertex distance. Other parameters determine how the lenses are to be positioned in the socket or how they fit into the socket

must be incorporated, e.g. the distance between the pupil centers when "looking into infinity" (pupil distance) or the translucent height.On other parameters can be used to calculate and manufacture eyeglass lenses particularly well tolerated and individual for the person, for example, the forward inclination of the socket and the lens angle.

In the context of the present invention, parameters for spectacle fitting are generally understood to mean information which is needed or usable for the spectacle fitting described above. These include, for example, dimensions relating to the head of the person, in particular regarding the eye area, a type of spectacle frame and

Dimensions of the spectacle frame and the seat of the spectacle frame in the face.

The parameters for spectacle fitting may in particular be centering parameters which can be used for the spectacle lens centering explained above and which are e.g.

describe anatomical features of the user (eg distance of the eye pupils) and a position of glasses on the head. Examples of such centering parameters are in the DIN ISO 13666, 2013-10 edition, namely, for example, monocular pupillary distance or pupil distance. The monocular pupillary distance is the distance between the center of the pupil and the midline of the person's nose or bridge

Spectacle frame in case the eye is in primary position. The primary position corresponds to the position of the eyes with straight head and posture and straight-ahead view. The glasses adjustment parameters may also include dimensions of a spectacle frame. The parameters for adjusting the glasses can be determined on the basis of a real spectacle frame worn by the person or also on the basis of a virtual spectacle frame which is adapted to a model of a head which is created on the basis of the depth information. In this case, the use of a virtual spectacle frame, the parameters for

Eyeglass fitting also includes a type of a selected eyeglass frame or parameters representing the selected eyeglass frame, e.g. Dimensions of the same, describe include.

By determining a distance between the depth information detection device and the head of the person to be examined, inaccurate positioning of the person to be examined, i. Positions that deviate from a desired target position, are compensated in the determination of parameters for eyeglass adjustment.

The method may further comprise determining a current head position (actual head position), in particular based on the depth information, e.g. compared with a desired head position. The head position may include the position of the head in space as well as its orientation (e.g., tilt, line of vision). The head position may, for example, a lateral head rotation (ie about the body axis of the person), a head position in the axial direction (relative to the measuring device) a lateral head inclination (ie in the direction of a shoulder) or a head inclination along the body axis (ie forward or backward ), wherein the head position relative to the device according to the invention, for example to the depth information detection device, can be determined. Head positions relative to the device according to the invention are relevant, for example, to the correct placement of the person in front of the device according to the invention (for example within the measuring volume). The

Head tilt (along the body axis) has a strong influence on the measurement of the

Viewing height. Consideration is therefore relevant to the lens centering and can be used for subsequent correction of the transparency height if necessary. The parameters for adjusting the glasses are determined on the basis of the determined actual head position. In this way, for example, deviations from the desired head position and / or head position (eg in the axial direction) relative to a device used can be taken into account in determining the parameters for spectacle fitting. The actual head position can be as above described include a lateral inclination of the head or an inclination of the head forward or backward. This is particularly relevant if the natural, habitual head posture of the person at the time of determining the parameters for spectacle fitting is to be taken into account, since the inclination of the head determines the determination of some parameters

Spectacle fitting, e.g. the determination of a premonition or the determination of an overview height, can influence. For this purpose, the person may be asked to take the natural head posture, which is then detected as actual head position. This detected actual head position is then used to determine the parameters for adjusting the glasses. Thus, the parameters for adjusting the glasses can be determined suitably for the natural head position.

For example, for this purpose, at least one coarse 3D model of the head can be created from the depth information, from which the head posture and head position of the user can be seen. In this way, the user can be given a feedback regarding the positioning of the head, for example, the user can be instructed to place the head for a measurement differently, for example, if relevant parts of the head can not be detected. In addition, it can also be ascertained if the head posture differs from a previously established habitual head posture of the user or if there is not a zero-sighting direction or main direction of vision desired for a measurement. Thus, the head of the user can be positioned as optimally as possible in the measuring range of the device.

Determining the parameters for adjusting the glasses can then be based on the recorded image of the head. The person can when taking the image a spectacle frame without lenses or with support discs (simple plastic discs without optical

Effect), or wear glasses with lenses (glasses with optical correction effect) or no spectacle frame. For example, such support discs are sometimes incorporated in new spectacle frames in an optometrist shop. In the latter case, the method can then measure the three-dimensional topography of the face and determine anatomical parameters (e.g., the distance of the pupils) as the parameters that can then be used for spectacle fitting. In particular, by using the three-dimensional topography, such parameters can be determined independently of the head position.

By taking the picture, additional information can be added to the picture

Depth information for determining the parameters for eyeglass adjustment are used, for example, taken from the image dimensions of the head of the person. In this case, the method may include scaling the recorded image on the basis of the depth information and / or scaling based on the image parameters for spectacle fitting based on the depth information. By scaling the captured image based on the depth information, a more accurate determination of the spectacle fitting parameters can be achieved since the captured image can accurately reflect dimensions and these dimensions can be extracted from the image.

The method may further include rectifying the captured image based on the

Include depth information. A rectification is to be understood as an alignment and / or equalization of the recorded image, so that e.g. Even with an oblique head position, which leads to distortions in the image, correct parameters from the rectified image

Eyeglass adjustment can be taken. The acquisition of the depth information and / or the taking of an image may be repeated several times, the method further comprising a combination of the respective generated depth information and / or images, e.g. through a temporal averaging. , A suitable method for this purpose is, for example, in "Rapid Avatar Capture and Simulation using

Commodity Depth Sensors "A. Shapiro, A. Feng, R. Wang, Hao Li, M. Bolas, G. Medioni, E. Suma in Computer Animation and Virtual Worlds 2014, Proceedings of the 27th Conference on Computer Animation and Social Agents , 05/2014 - CASA 2014 described.

By means of such averaging, the accuracy of the determination of the parameters for adjusting the glasses can be increased. However, multiple depth information and / or multiple images may be combined differently than with averaging to increase accuracy.

For example, this combining may be a temporal adaptation of a function (or functions), eg, adaptation of a polynomial function or other suitable function, or a combined spatial and temporal adaptation of the function, eg polynomial and spline functions If the function is temporally adjusted, adaptation takes place via a plurality of depth information or images taken in chronological succession, or spatially via the images or the depth information (for example: across different parts of the detected face) during a combined spatial and temporal adaptation one or more corresponding functions adapted to the depth information and / or images, for example by adaptation of coefficients of the function (eg polynomial coefficients in a polynomial function) that the function as close as possible to the depth information and / or images. Further

Processing steps may then be based on the function or functions.

Combining the images or depth information, e.g. By averaging or fitting a function, it can be done using a rigid registration method (i.e., a method that uses only rotations and translations) to accommodate different depth information and / or captured images. Thereby, parts relating to the same part of the head, e.g. Measurement data, the depth information or parts of the images relating to the same part of the head brought to coincide. This is especially necessary when the head moves between the individual measurements. However, non-rigid methods (i.e., methods which also use other operations such as distortions) may be used wholly or for some parts of the depth information and / or images, e.g. to account for movements such as eyelid movements, such as the Dynamic Fusion method (described, for example, in "Dynamic Fusion: Reconstruction and tracking of non-rigid scenes in real-time", Richard A.

Newcombe, Dieter Fox, Steven M Seitz; The IEEE Conference on Computer Vision and Pattern Recognition (CVPR), 2015, pp. 343-352).

Preferably, such non-rigid methods are used only for areas of the face which either are not relevant for the later determination of parameters or can move quickly. The two types of registration methods mentioned above for matching the different measurements (depth information and / or images) can be performed independently or in combination. The method may further include discarding images and / or depth information that meets predetermined criteria. These criteria may include, for example, the presence of a head posture unsuitable for measurement, e.g. such that parts of interest such as eyes are invisible or include a closed eyelid. As a result, less suitable images and / or depth information (e.g., images with an eyelid closed) may be discarded to determine the parameters for eyewear adaptation.

The method of the first aspect may further comprise, the method of the second aspect further comprising: presenting a model of the head based on the depth information, and virtually fitting glasses to the model, wherein the parameters for adjusting the glasses are determined based on the virtual fitting. In such a case, it is preferable that the person wearing the depth information and possibly the images does not wear glasses, so that a model of the head without glasses can be made easier. Different eyewear frames can then be adapted to this model virtually, ie also as models eg on a display. From the virtual fitting then the parameters for adjusting glasses can be determined, for example, a type of glasses then to be used real, dimensions of the then actually used glasses and / or Zentrierparameter this.

So here it can be the acquired depth information, possibly together with

recorded images, also displayed as a 3D model of the head on a display. In other words, in this case, a 3D model of the head at appropriate

 Repeat rate of the depth information detection device are displayed in real time, which corresponds to a virtual mirror. This 3D model can then be combined with various virtual spectacle frames to give the person a first impression of the optical effect of different spectacle frames. One of the spectacle frames can then be selected. The type of this spectacle frame can also be used as a parameter for

 Eyeglass adjustment can be viewed. It is also possible in such an adjustment of a virtual spectacle frame parameters for spectacle fitting, which are then used to adjust a real glasses to determine, and describe the dimensions of the spectacle frame. This can be done, for example, by varying such parameters until optimal matching is achieved. Examples of such parameters are e.g. Disc width, disc height and bridge width of the spectacle frame. For example, the eyeglass bridge can be adapted to the shape of the nasal bridge in the 3D model.

Centering parameters can then also be determined on such a selected virtual spectacle frame on the 3D model of the head. In other words, with embodiments of the present invention centering parameters with real

Spectacle frames (which are worn in the measurements of the person) or with virtual spectacle frames (which are adapted to a 3D model of the head) are made.

There is also provided a computer program having a program code which, when executed on a processor, causes the processor to be one of the above

executes described method and / or its execution controls. The

Computer program may be stored on a computer readable medium. According to a third aspect, there is provided an apparatus for determining parameters for adjusting glasses, comprising depth information detection means for detecting depth information relating to a head of a user, wherein the

Depth information comprises at least one distance of the head to the device, and an evaluation device which is adapted to determine parameters for adjusting the glasses based on the detected depth information.

By determining a distance between the depth information detection device and the head of the person to be examined, positions of the person to be examined, which deviate from a desired position or preferred position, can be compensated for in determining the parameters for adjusting the glasses.

The depth information acquisition device may comprise a light field camera. Such a light field camera is also referred to as a plenoptic camera.

Light field cameras capture, in a sense similar to holographic recording systems, the so-called light field of a scene. Not only are intensity information recorded as in a conventional camera, but additional information about the direction from which a respective light beam comes. The recorded signal (which is recorded, for example, with a conventional image sensor) thereby contains in a light field camera both image information and depth information obtained from the intensity information and the information about the direction of the light rays. This allows a captured object, such as the person's head, to be at least to some degree (depending on the implementation of the

Light field camera) are reconstructed three-dimensionally, and distances between the head and the light field camera are detected. With such a light field camera so can

For example, the functionality of the depth information detection device and the

Functionality of a camera. As a result, a correspondingly compact construction is possible.

In some embodiments of such light field cameras is a

Used multi-microlens arrangement, which is mounted in a defined plane in front of an image sensor. The individual lenses of the microlens array generate different image information on the image sensor. From the entire image information on the image sensor, the light field can be reconstructed. The depth information acquisition device may be configured to detect a depth profile of a region of interest of the head. A depth profile is an indication of a distance of points of the region of interest from a reference surface (eg defined by the depth information acquisition device) as a function of a position in a plane parallel to the reference surface, for example a position in one

captured 2D image. On the basis of the depth profile, the evaluation device can display a model of the region of interest, as it were, as a virtual mirror, which is known e.g. enable a virtual adaptation of glasses. It should be noted that the user at the time of generating the depth information and image information either a

Can wear glasses frame, or can wear no glasses frame. For the virtual adjustment of spectacle frames, it is advantageous if the user when recording no

Wearing spectacle frame.

The depth information detection device may operate based on infrared radiation. As a result, a user is not disturbed by the measurement. For example, a camera-based infrared depth sensor in which an infrared pattern of a

Projection system is generated and the depth of the objects in the scene are averaged by recording the so-lit scenery with an infrared camera, so for example, a depth profile of the head can be created. Such depth sensors are commercially available. They allow comparatively high refresh rates, for example of 30 Hz or 60 Hz.

Instead of infrared patterns, patterns in the visible light range can also be used.

Such methods are also known by the term strip projection. In the process, various image patterns and / or image sequences are projected onto a surface (in this case upside down) and an image of the object taken with a camera (which may be or differ from the above-mentioned 2D camera). The camera stands at a defined angle to the projection system. The three-dimensional surface of the target, here the head, and the triangulation base (that is, the distance between the projector and the camera) make the patterns imaged on the camera's sensor changed or deformed, from which the depth information and topography of the illuminated surface are determined can be. In particular, the distance of the head from the depth information acquisition device can thus also be determined. However, the use of infrared light as described above is preferred because in this case a normal

Image capture is not disturbed and, for example, the user is not affected by the

Light pattern is irritated. The depth information acquisition device may comprise a transit time sensor, via which the distance is determined over a transit time of a signal, wherein the transit time can be measured directly or in the form of a phase shift.

In such runtime sensors is essentially a signal from the

Depth information detection device sent to the head and detects a signal reflected from the head. From the duration of the signal to and from the head and the speed of the signal, the distance can then be determined, this being

For example, by a scanning method can also be done at a variety of points. Instead of measuring the transit time directly, a phase difference between a modulation of the reflected beam and a corresponding modulation of the reference beam derived from the transmitted beam is frequently determined-in particular if light pulses are used as a signal.

Instead of light pulses, however, other types of signals, for example

Ultrasonic signals are used.

Particular preference is given to using travel time sensors, which are so-called

Runtime cameras used with lateral resolution depth sensors. Examples of suitable

Sensors for such time-of-flight cameras are Photonic Mixing Device (PMD) sensors, which use a modulated light signal, such as infrared light, to illuminate the head, and detect the reflected light with the PMD sensor also on A modulation source used for the modulation is coupled, ie the transit time is measured indirectly via a phase shift.

With corresponding time-of-flight sensors, objects such as the head can be scanned at a high refresh rate, for example in the range of 30 to 60 Hz and high resolution, so that depth information with refresh rates comparable to a video rate can be made available. In this case, an entire depth profile of the head can be created.

By such time-of-flight sensors, it is thus possible to determine depth information with a high repetition rate and / or high accuracy. Even a robust detection of depth information, largely independent of room lighting, etc. can be realized because, for example, no corresponding points have to be found in stereo image pairs.

Another type of depth information detection device, which at

Embodiments can be used, uses a distance measurement by means of optical triangulation, such as laser triangulation. The principle of the optical

Triangulation is based on the fact that a light spot on the object to be measured (in the present case the head or a part thereof) with a laser, a light emitting diode (LED) or another light source is generated. This can be done in the visible range or in the infrared range. The light spot is imaged via a camera, for example a CCD camera (charge coupled device), a CMOS camera or a line scan camera. The light source and the camera are at a defined angle to each other Due to the trigonometric relationships can be determined from the displacement of the imaged light spot on the sensor, that is, the location of the light spot on the sensor, the distance to the object to be measured. In particular, the light spot in the image shifts with increasing distance to the object to be measured in a direction from the light source to the camera, because due to the angle between the light source and camera, the light also covers a greater distance in the direction of the camera with increasing distance. Such a measurement can also be done line by line. For this purpose, for example, a laser line is projected onto the head. From a camera image of the laser line can then

Depth information along the laser line are transmitted in particular on the basis of shifts perpendicular to the direction of the laser line. Thus, the topography of the head along the line can be determined. With a scanning system in which the laser line moves over the head, then the entire head or a part of interest thereof, for example an eye area including a pair of spectacles, can be measured.

It must be ensured in particular when using a laser light source that the eyes of the person to be examined by the laser can not be damaged.

In particular, the intensity of the laser is to be chosen sufficiently low. Here infrared light is preferred.

A camera for such an optical distance measurement by means of triangulation can be one of a possibly additionally provided for image recording 2D camera, separate camera. It can also be used a single camera device, for example, at

Use of visible light areas outside the above-mentioned laser line or can use other light lines for image recording and at the same time can accommodate the laser line, or when using infrared light, for example by means of a

switchable filter periodically between the measurement of depth information and the recording of an image can be switched. In other embodiments, none at all

Image acquisition is performed with a 2D camera, but it is merely an example, with a scanning system as described above, in which a laser line is moved over the head, a total depth profile and thus determines the topography of the head.

In a further embodiment, the depth information can also by a

Stereocamera method be determined by triangulation. In contrast to the above-mentioned EP 1 844 363 B2, here a pair of cameras is not only used to determine a 3D model, but it is also explicitly a distance from the head to the

Stereo cameras determined. In this case, two are used at a predetermined angle to each other or more at several predetermined angles to each other arranged cameras.

When using two cameras, e.g. of a stereo camera system, the depth determination of an object point is made by determining the parallax of the respective object point in the two camera images, that is to say a displacement of object points between the camera images. The error of such a depth measurement is proportional to the square of the distance between the cameras and the head and inversely proportional to the stereo base, that is, the distance of both cameras. Thus, the stereo base must be sufficiently large enough for typical distances in the operation of the

Device to achieve sufficient accuracy to obtain the depth information. "Sufficient accuracy" means in particular that the parameters for

Eyewear adjustment can be determined with a desired or required for the eyeglass adjustment accuracy.

Since corresponding points or areas in the two image recordings must be identified in this approach, the area of the head to be examined must have sufficient structure (in particular lines or edges) to be such

Identify correspondence with a method used for this purpose. Objects that usually do well include the eyes, eyebrows, nose, and other prominent facial features. In addition, in some embodiments, a structure may still be projected upside down, such as binary patterns, lines, dots, etc., around the

Identification corresponding area to facilitate. When implementing the depth information acquisition device, for example, as a runtime sensor or as a light field camera, however, a more compact structure than, for example, with a

Stereo camera system possible because no angle between two cameras must be provided. Thus, time-of-flight sensors, light field cameras and the like are known

 Depth information detection devices in cases where it depends on a compact design, compared to a stereo camera system preferred.

The present invention is not limited to the above-described types of

Depth information detection devices limited. It can too

 Depth information detection devices are used with other depth sensors, for example, as already mentioned, ultrasonic depth sensors, depth sensors, which perform a depth measurement by means of optical coherence tomography (OCT), confocal sensors or chromatic confocal sensors. Overall, any conventional depth sensor can be used, which can capture a depth information with respect to the head, in particular with respect to the eye area and the glasses, sufficiently accurate and thereby does not pose a risk to the eyes of the user (for example, due to excessive radiation). "Sufficiently accurate" again means that finally the parameters for adjusting the glasses can be determined with an accuracy desired or required for adjusting the glasses.

The apparatus further includes, in addition to the depth information acquisition device, a 2D camera, i. a (conventional) camera for taking two-dimensional images by means of an image sensor, for taking an image of at least a part of the head. This provides additional information for determining the parameters

 Eyeglass adjustment available, for example, taken from the picture dimensions of the head of the person.

The evaluation device can be set up for scaling the images on the basis of the depth information and / or for scaling based on the images of certain parameters for adjusting glasses based on the depth information as already explained above.

The evaluation device can also rectify the images based on the

Depth information to be set up, as already explained above. The device is set up such that the depth information acquisition device and the 2D camera detect the head via a common optical axis. In the case of the depth information acquisition device, the optical axis corresponds to an axis on which the depth information is detected, that is to say a "viewing direction" of the axis

Depth information detector. If the depth information acquisition device uses imaging optics, then the optical axis corresponds to the optical axis of this imaging optic, usually a straight connecting line of all centers of curvature of refractive or reflecting surfaces of the imaging optics. Light rays on the optical axis pass through the imaging optics without deflection. In the case of the 2D camera, the optical axis corresponds to the optical axis of the lens of the 2D camera as described above for imaging optics.

In some embodiments, a beam splitter may be used to combine and separate the optical axes of the depth information acquisition device and the 2D camera. The beam splitter may be a wavelength-selective beam splitter. In such embodiments, for example, the 2D camera can record visible light, while the depth information detection device operates on the basis of infrared radiation. In other embodiments, the beam splitter is not wavelength selective, and the 2D camera and depth information acquisition device at least partially share an equal portion of the spectrum. By such an arrangement, a more compact

Device can be achieved as in a stereo camera or the like, since no

corresponding angle must be provided for example between image recording devices. In addition, depth information and image information of the camera are taken from the same direction, whereby a perspective correction of the depth information relative to the image data can be omitted.

The evaluation device can be set up based on the depth information

Head position of the head to determine, wherein determining the parameters for

Eyewear adjustment based on the specific head position.

The apparatus may be arranged to detect the depth information by the

Depth information detection device and / or the recording of the images with the 2D camera to repeat several times, wherein the evaluation device then for combining a plurality of acquired depth information and / or a plurality of recorded images, for example in the form of an averaging as described above, is set up. The evaluation device can also be set up to discard images and / or depth information that fulfill predetermined criteria.

The evaluation device can be further set up, a model of the head based on the depth information, e.g. to display on a display, and to allow a virtual fit glasses to the model, wherein the evaluation device is adapted to determine the parameters for adjusting the glasses based on the virtual fitting.

The present invention will be explained in more detail below with reference to various embodiments with reference to the accompanying drawings. Show it:

1 is a schematic representation of a device according to an embodiment,

Fig. 2 is a schematic representation of a device according to another

Embodiment,

Fig. 3 is a schematic representation of a device according to another

4 shows a schematic illustration for explaining depth sensors which can be used in the exemplary embodiments,

Fig. 5 is an illustration of a section through a depth profile, as in some

Embodiments can be generated,

FIGS. 6A-6F are explanatory views of spectacle fitting parameters;

7 is a flowchart for illustrating a method according to FIG

Embodiment,

8 is a flow chart illustrating a method according to another embodiment, and

Figures 9 and 10 are illustrations for explaining a rectification, as performed in some embodiments. In the following, various embodiments of the present invention will be explained in detail.

In Fig. 1, a device for determining parameters for fitting a pair of spectacles (i.e., parameters that can be used to adapt a pair of spectacles to a person's head) is shown schematically in accordance with one embodiment. The device of FIG. 1 comprises a depth information acquisition device 12 for determining a depth information relating to a head 10 of a user, in particular for determining a depth information relating to an eye area, that is, an area around the user's eyes, thereof. The user in Fig. 1 wears a pair of glasses 1 1, with respect to which also a depth information can be determined.

A depth information in the sense of the present application comprises at least one piece of information regarding a distance of the user, in particular the head 10 of the user and / or the spectacles 1 1 worn by the user, to the user

 Depth information detection device 12. For example, as a distance, the length of the dotted line 14 of FIG. 1 can be determined. However, distances can also be measured to other and / or multiple locations of the head 10. In a preferred embodiment, a depth map is created as it were, for example, by determining the above-described distance for a plurality of points of the head 10, in particular the eye area, and / or a plurality of points of the spectacles 1 1. The depth information provided by the depth information acquisition device 12 thus provides information about such a distance. This information can be used below to determine regardless of the exact position of the head 10 parameters for adjusting the glasses 1 1 to the head 10 of the user, for example, for centering eyeglass lenses. Examples of suitable depth information detection devices as well as parameters to be determined will be explained later in more detail.

The apparatus of Fig. 1 further comprises an evaluation device 13, which the

Depth information from the depth information detection device 12 receives and based on the depth information determines parameters for adjusting the glasses 1 1. The

Evaluation device 13 can be programmed, for example, as appropriately programmed

Computing device, for example in the form of a computer to be executed. However, hardwired hardware components such as application specific integrated circuits (ASICs) may also be used. The evaluation device 13 can in a conventional conventional manner output means such as a display, speakers, interfaces for outputting signals and the like, for outputting or transmitting the particular parameters for spectacle fitting to other means. Details of the determination of the glasses adjustment parameters will also be explained later. It is to be noted that the depth information detecting device 12 and the

Evaluation device 13 of the device according to the invention can be arranged locally close together, for example in a common housing or in separate housings, which are in a fixed spatial arrangement to each other. Likewise, however, the evaluation device 13 also spatially separated from the

Depth information detection device 12 may be arranged, and that of the

 Depth information detection device 12 determined depth information can be transmitted in a conventional manner wireless, wired or via optical lines such as glass fibers to the evaluation device 13. Such a transmission is also possible, for example, via networks such as the Internet, so that essentially arbitrary distances between the depth information acquisition device 12 and the evaluation device 13 are possible.

Before various details of depth information acquisition devices, parameters for adjusting glasses and the determination of the same are explained in more detail, variations and extensions of the invention will now be described first with reference to FIGS. 2 and 3

Embodiment of Fig. 1 discussed. To avoid repetition in the following description, the same or corresponding elements in different figures bear the same reference numerals and are not explained in detail several times. In the apparatus of Fig. 2, the apparatus of Fig. 1 is extended by a camera 20 which receives a two-dimensional image, such as a black-and-white image or a color image, of the head 10 or a portion thereof, such as an eye area. The camera 20 may be conventionally provided with a lens and an image sensor

be implemented.

The image recorded in this way is likewise supplied to the evaluation device 13. The

Evaluation device 13 additionally determines the parameters for adjusting the glasses on the basis of the recorded image in this case. The evaluation device 13 can also control the camera 20 and the depth information acquisition device 12 in such a way that the image is recorded simultaneously with the depth information. For evaluation, in one variant, for example, the image taken by the camera 20 can then be scaled on the basis of the depth information acquired by the depth information acquisition device 12. For example, such scaling may be done with a higher scaling factor if the depth information indicates that the head 10 is farther from the depth information acquisition device 12, and scaled with a smaller scale factor as the head gets closer to the depth

 Depth information detection device 12 is. The scaling factor may indicate an increase or a decrease.

In this way, in particular the image can be scaled such that the image

Dimensions of the head 10 are sufficiently accurately removed, which the

"Sufficiently accurate" means that ultimately the parameters for adjusting the glasses can be determined with an accuracy desired or required for adjusting the spectacle .. Instead of scaling the image, in another variant, the parameters can be determined however, corresponding dimensions may also be taken from the captured image, and the dimensions taken may then be scaled based on the depth information In Figure 2, the camera 20 is shown separate from the depth information acquisition device 12. However, in some embodiments, the camera 20 may also be part of it serve the depth information detection device 12, for example in the case of a stripe projection or a laser triangulation, as will be explained in more detail later.

In the embodiment of FIG. 2, the camera 20 and the work

Depth information detection device 12 as shown at different angles and with different optical axes. In other embodiments, a structure is provided in which depth information detector 12 and camera 20 view the head 10 coaxially. A corresponding embodiment is shown in FIG. 3.

In Fig. 3 are as in the embodiment of FIG. 3 a

 Depth information detection device 12 and a camera 20 is provided. In the embodiment of Fig. 3, a beam splitter 30 is additionally provided, which the optical axis of the camera 20 with the optical axis 12 of

Depth information detection device 12 combines so that the head 10 on a single considered optical axis, or is measured. This also makes a compact design possible. In addition, parallax errors and the like between the depth information and the image taken by the camera 20 are avoided or reduced. In which

Embodiment of Fig. 2, such parallax errors and the like, however, can be eliminated by calculation by the evaluation device 13.

The beam splitter 30 may be a wavelength-selective beam splitter. In such

For example, the camera 20 may record visible light while the depth information detector 12 operates based on infrared radiation. Alternatively, the beam splitter 30 is not wavelength selective, and the camera 20 and depth information detector 12 at least partially share an equal portion of the spectrum.

Even if it is not shown explicitly in FIG

Depth information detection device 12 provided depth information and of the

Camera 20 provided one or more images from an evaluation as the evaluated for the evaluation device 13 of FIG. 1 are evaluated to parameters for

To obtain eyeglass adjustment. Next, various kinds of depth information detecting means which can be used to obtain the depth information will be explained in more detail.

For example, runtime or phase position measurements can be used to obtain the

Depth information can be used. In such methods, as explained above, substantially a signal from the depth information detecting means is sent to the head and a signal reflected from the head is detected. With appropriate

In this case, time-of-flight sensors can scan objects such as the head 10 with a high refresh rate of, for example, in the range from 30 to 60 Hz and high resolution, so that the depth information can be made available with refresh rates comparable to a video rate. In this case, an entire depth profile of the head can be created. On the basis of such depth profiles, as in the embodiment of FIG. 1, parameters for

Glasses adjustment can be determined in principle without the use of another camera such as the camera 20. FIG. 4 schematically shows a depth information acquisition device, which serves as a schematic illustration for various types of use that can be used Depth information detection devices can serve. In the case of a runtime sensor, 40 denotes a signal source, for example, a modulated light source, and 41 denotes a corresponding sensor for detecting the received light, for example, a runtime camera as described above.

As already explained, another type of

 Depth information detection devices that can be used in embodiments, a distance measurement by means of optical triangulation, for example

Laser triangulation. In the case of FIG. 4, in such a triangulation device, for example, 40 may denote a light source and 41 a camera which are at a defined angle to one another.

Another possibility for implementing the depth information acquisition device 12 is the use of a light field camera.

Further possibilities for implementing a depth information device, as described, are a camera-based infrared depth sensor in which an infrared pattern is generated by a projection system and the depth of the objects in the scene is determined by recording the scene thus illuminated with an infrared camera. As also described, a stripe projection with visible light can also be used.

 In the case of FIG. 4, for example, the element 40 would then be the projection system, and the element 41 the camera, which may be identical to or different from the camera 20. In another embodiment, as described, the depth information may also be determined by a stereo camera method using triangulation. In this case, two or more cameras are arranged at one or more predetermined angles. In the case of FIG. 4, in such a depth information acquisition device, for example, 40 is a first camera and 41 is a second camera.

By using such depth sensors as described above can at

corresponding high-resolution depth sensors a profile of the head 10 and thus the three-dimensional surface of the head 10 based on the

Depth information acquisition device alone to be modeled. As an example, Fig. 5 shows a schematic representation of a section 50 through such a 3D model, in which a section 51 is visible through the glasses. The section 50 in the example of FIG. 5 is indicated by a The user's eye 52 does not pass through the center of the subject's face but through the center of the eye. 10, the profile of the head is indicated as shown in Figures 1 -4, wherein this profile extends through the central axis of the head and thus differs from the profile 50.

On the basis of the depth information, which is a distance between the

 Depth information detection device and the head 10 includes, a true to scale such three-dimensional profile of the head 10 can be created with appropriate

Cut 50 in different places. This can in turn parameters for

Eyeglass adjustment as Zentrierparameter be determined. This will be explained in more detail below.

First, different parameters for spectacle fitting, in particular centering parameters, will be explained with reference to FIGS. 6A to 6F. FIGS. 6A to 6F respectively show views of spectacles, possibly together with a partial view of a head, in order to explain various parameters.

FIG. 6A shows the monocular pupil distance when looking at infinity. An arrow 60A shows the monocular pupillary distance for a left eye, measured as the distance between the pupil and a central axis 61 of the head. An arrow 60B shows the monocular

 Pupil distance for the right eye. The values for the left and right eyes are different in most cases.

Fig. 6B illustrates the view height measured again when looking at infinity, satisfying the eye pivot requirement. The eye pivot requirement means that the optical axis of the lens should pass through the eye pivot. The optical axis runs through the optical center of the spectacle lens and is generally perpendicular to the spectacle lens. This can minimize undesirable prismatic effects when viewed through eye movements through different parts of a spectacle lens. The see-through height indicates the distance between the pupil and a lower edge of the spectacle lens. An arrow 62A shows the viewing height for the right eye, and an arrow 62B shows the viewing height for the left eye.

In Fig. 6C, 63 denotes the corneal vertex distance, which is usually measured from the back of the spectacle lens of the spectacles to a peak plane of the cornea. In Fig. 6D, an angle 64 denotes the front inclination of the socket, essentially one Inclination of the glasses to the vertical. As well as the viewing height shown in FIG. 6B, this also depends on the person's head posture.

In Fig. 6E, an angle 65 designates the lens angle, an angle at which the lens is compared with a "plane" lens, and finally Fig. 6F

various dimensions of the spectacle frame itself indicated. 67 is the disk width, with 68 the disk height. Disc width and disc height together with pupil distance and viewing height are important information for determining a required glass diameter of a spectacle lens. With 66 also the bridge width of the spectacle frame is designated.

FIGS. 6A to 6F show some spectacle fitting parameters which can be determined by means of the illustrated devices. Other parameters for adjusting the glasses can also be determined. For example, there are optionally further parameters which can be determined for the centering of spectacle lenses for near vision (for example for reading glasses or working glasses) and for the centering of progressive lenses. This includes, for example, the "near-pupil distance", which is not measured infinitely in the direction of view as described above, but when looking at an object located near the head.

In addition to the parameters for spectacle fitting shown in FIG. 6F, other geometric information about the spectacle frame can also be determined. This geometrical information can be important for the selection of suitable spectacle lenses, since they have an influence on the glass thickness, for example, in spectacles having a positive optical effect.

At least in the centering of single vision lenses is usually the

Eye pivot request fulfilled. In the case of the centering of the height, that is to say the alignment of the optical axis of the spectacle lens in the vertical direction, the head posture must be taken into account, since the inclination of the head influences the measurement of the viewing height and also the pretilt of the frame. In order to take this into account, it can be ensured, for example during a measurement by the discussed device by the person's head posture, that the plane of the spectacle frame is perpendicular to the ground, which is also referred to as the zero-sighting direction. In this state is then discussed with the

Device determines the position of the pupils in the plane of the spectacle lens. It is also possible to determine the viewing height in natural head and body posture, the person to be examined usually looks in 8 to 10 m on the ground, which also as Main direction is called. The head posture can, as will be explained in more detail below, also be determined by means of the device according to the invention, and the person to be examined may, if necessary, be instructed to change the head posture.

The approaches for determining centering parameters on the basis of the depth information and optionally on the basis of a camera image (for example taken with the camera 20 of the preceding exemplary embodiments) will now be explained in more detail below with reference to FIGS. 7 to 10.

FIG. 7 shows a flowchart which gives an overview of a method according to an exemplary embodiment for determining parameters for adjusting glasses. FIG. 8 then shows a detailed flow chart in which various possible details of such a method are illustrated. While the methods are presented as a series of steps, the illustrated order should not be construed as limiting.

 In particular, some steps may also be performed in a different order, or one or more steps may be executed in parallel. For example, a depth information and an image may be recorded simultaneously with a depth information acquisition device such as the depth information acquisition device 12 of FIG. 2 and a camera such as the camera 20 of FIG. 2 or also with a light field camera as explained above.

In a step 70 in FIG. 7, depth information is detected which includes a distance of a head from a device used to acquire the depth information. This can be done with depth information detectors 12 as discussed above.

In step 71, an image (also referred to as an overview image) of at least one region of interest, for example an eye area, of a head is additionally detected. Step 71 is optional, and in some embodiments only the depth information is captured in step 70. In step 72, parameters which are used for spectacle fitting, in particular spectacle lens centering, are then determined. For example, one or more of the parameters discussed with reference to FIGS. 6A-6F may be determined.

For this purpose, in some embodiments, a true-to-scale 3D model of the head with glasses is created from the acquired depth information, and the parameters are then read from this 3D model. In addition, when an overview image has been acquired, the Overview image to be registered to the 3D model, for example, used to give the 3D model texture. This facilitates the detection of individual features such as

for example, the eyes. Approaches for detecting such features as the eyes, the eyeglass frame, and the like, which are needed to determine the parameters, are known per se, for example, from conventional photography where various face recognition algorithms are used. The distance of the head to the depth information detection device can be used to ensure a correct size of the 3D model even with a positioning of the head, which does not correspond to a predetermined target position.

In other embodiments, the depth information may include only a single distance between the head and the device at a single point, and in addition an overview image is taken. Such depth information can be provided with a relatively simple depth sensor which, for example, need not be designed to be scanned. In this case, the distance thus obtained is used to scale the image with a scaling factor which depends on the distance and which is in the

Essentially directly from the set of rays. Thus, the recorded image can be scaled to a correct size, and dimensions such as the dimensions shown in FIGS. 6A to 6F can be taken from the thus scaled overview image. Depending on the direction in which a single picture is taken, only the determination of some parameters is necessary. For example, from a frontal image, parameters of FIGS. 6A, 6B, and 6F may be determined, while for the parameters of FIGS. 6C and 6D, an image must be taken from the page. Depending on the parameters to be determined, a number of image recordings may therefore be carried out in such a case.

In some embodiments, the depth information thus compensates for the size of the head of the person to be examined or relevant parts thereof changing as a function of a distance of the head from the camera used. For example, the head appears larger when it is closer to the camera and smaller when it is away from the camera.

Referring now to FIG. 8, various details and extensions of the method of FIG. 7 will be discussed. While FIG. 8 and the following description explain various possible extensions and details in combination, it should be noted that these can also be implemented independently of each other, that is not so

necessarily be implemented in combination with each other. In step 80, depth information is repeatedly detected, and optionally image information is repeatedly recorded in step 81. Thus, steps 70 and 71 of FIG. 7 are repeatedly performed. As already explained, some depth sensors offer high levels

Refresh rates in the range of 30 Hz or 60 Hz, ie in the range of typical video rates, and also cameras can record image information with such rates. However, lower repetition rates are possible. These measurements at 80 and 81 can be analyzed with appropriately equipped computers in real time, at least in some aspects.

As already explained, from such repeatedly acquired depth information, a model of the head can then be created and displayed on a display, which makes it possible, for example, to adapt a virtual spectacle frame as described. Also, the

Depth information as described can be used to align the head.

In step 82, then from the measurements made at 80 and 81, appropriate

Measurements are selected. Thus unfavorable images or depth information for the later determination of the parameters for spectacle fitting can be excluded.

For example, the position of the pupil, which is required for example for the parameters shown in FIGS. 6A and 6B, can only be inaccurate with the eyelid closed

determine. Therefore, with appropriate detection of facial features (also referred to in the English literature as facial feature detection or Landmark Detection) can be determined in which images or in which depth information one or both eyelids are closed, and corresponding data can for the

subsequent processing steps are discarded. It should be noted that the acquisition of the depth information and the taking of the images at 80 and 81 can also be synchronized, so that, for example, one image each of a set of

Depth information is assigned. For example, if it is found in the image that the

Eyelid is closed, also the corresponding depth information can be discarded. Conversely, if, for example, it is found in the depth information that the head has been turned so far that a reasonable determination of desired parameters for adjusting the glasses is difficult or impossible, the corresponding image can also be discarded. Next, in step 83, a combination of multiple measurements and / or registration of data with each other may be made. Under registration will be included generally understood a process in which several records are brought to line or aligned. In the case of so-called rigid registration methods, the topography of the individual measurements is not changed, ie distances and angles are retained, but the individual measurements are brought into coincidence only by rotation and translation.

In this way, a plurality of successive measurements (in steps 80 and 81 of FIG. 8) can be combined after registration, which can bring about an improvement in accuracy, in particular with regard to the depth information. The parameters for the registration can be determined by conventional optimization methods, for example the ICP (Iterative Closest Point) algorithm for data without texture, homographic estimation, for example by means of a DLT algorithm for image data (direct linear transformation, for example for image data taken with a camera). , However, such rigid registration methods for combination can be problematic with variable facial areas (for example, moving eyelids) because unfavorable registration can occur here, in particular for display purposes on a display or the like. In preferred embodiments, therefore, such image areas or regions of depth information, where typically fast

Changes may occur (especially eyelid, eye movements and the like) are not used rigid method.

In step 84, a head posture is then determined in the measurements of steps 80 and 81. This head pose can then be used to rectify captured images, or otherwise, for example, in determining the parameters for

Eyeglass adjustment can be used for correction.

In one embodiment, with registration methods such as those discussed above with respect to step 83, the head of the person being photographed is registered with a standard head (that is, a 3D model of a head of a standard set shape) and the

Posture of this standard head is determined with respect to a reference coordinate system of the device. This reference coordinate system is also determined as a world coordinate system. For this purpose, in one embodiment, the rigid transformation is determined, which gives the standard head in its own frame of reference in a standard head in the

World coordinate system transformed so that a best possible match with the measurement data of the depth information detection device is achieved. This transformation can be described, for example, by means of the following six parameters: translation in the x, y and z directions, and rotation about the x, y and z axes (for example according to the Euler formula), where x, y and z describe axes of a world coordinate system. As an example, a head 10 is shown in Fig. 9, which is rotated by an angle 90 about the z-axis (perpendicular to the image plane). With 91, the center axis of a straight-headed head is designated, with 92 the central axis of the head 10. Here would therefore by the

Registration of angles 90 is determined. In a corresponding manner, translations or rotations of the head 10 about the x and / or y axis can also be determined.

The head pose thus described with these six parameters is then used in step 85 described below to correct for any skew of the line of sight to the device. In this way, for example, a visual point, that is to say the point of intersection of the respective visual axis of the person with a plane of the spectacle lens, can be corrected.

One way to apply a correction in advance is to rectify the

Camera image (eg, the images taken in step 81) in step 84 to convert the camera images to an image plane corresponding to an orientation of the face. This will be explained with reference to FIG. 10. In Fig. 10, in turn, the head 10 in the position of Fig. 9 is shown. Indicated at 100 is an optical center of a camera used (for example, the camera 20 of the above-described embodiments). 101 denotes an image plane of the central projection from the center 100, for example an image plane, according to which the image is taken by the camera 20. Due to the inclination of the head 10, distortions arise, for example, between the left and right half of the face. In the rectification, the points of the image plane 101 are converted into an image plane 102 substantially in accordance with the light rays drawn, resulting in equalization, and the thus corrected image is adjusted to the orientation of the face because the image plane 102 is closer to the orientation than the image plane 101 , From such equalized (and optionally scaled as discussed above) parameters for spectacle fitting can then be taken.

In step 85, as already indicated above, an analysis of the depth information and / or images, which have been preprocessed in steps 82 to 84, is carried out in order to determine the parameters for adjusting the glasses. This can, as already explained, essentially with algorithms for the detection of facial features or other features (for example the spectacle frame), and corresponding parameters for spectacle fitting can then be determined by corresponding distance or angle measurements in the data, for example in a 3D model created on the basis of the depth information and / or in image data scaled and / or rectified on the basis of the depth information. be performed. In this way, the parameters for adjusting the glasses, in particular the centering parameters, can be determined in a simple manner.

As already explained, in some embodiments, only some of the steps explained in FIG. 8 can also be carried out. For example, steps 83 and 84 may also be performed independently of each other, and may also be performed when only one measurement of depth information is made or only one measurement of depth information and one image taken. In other words, the multiple image acquisition and averaging can also be omitted.

LIST OF REFERENCE NUMBERS

10 head

 1 1 glasses

 12 depth information detecting device

13 evaluation device

 20 camera

 30 beam splitter

 40 component

 41 component

 50 depth profile

 51 glasses

 52 eye

 10 head profile

 60A, 60B pupillary distance

 61 midline

 62A, 62 B Clearance height

 63 Corneal vertex distance

 64 forward inclination

 65 frame angle

 66 Bridge width

 67 disc width

 68 disc height

 70-72; 80-85 process steps

 90 angles

 91 central axis

 92 central axis

 100 optical camera center

 101 image plane

 102 Rectified image plane

Claims

 claims

A method of determining spectacle fitting parameters (60A, 60B, 62A, 62B, 63-68) comprising:

 Detecting (70; 80) depth information regarding a user's head (10), the depth information comprising a distance (14) between the user's head (10) and a device used for detection, and determining (72; 85) parameters for spectacle fitting (60A, 60B, 62A, 62B, 63-68) based on the depth information,

 Taking (71; 81) a 2D image of the head,

 wherein the taking (71; 81) of the 2D image and the detection (70; 80) of the

 Depth information on a common optical axis takes place.

The method of claim 1, wherein the method further comprises determining a

Head position of the head (10), wherein determining the parameters for

Spectacle fitting (60A, 60B, 62A, 62B, 63-68) is based on the determined head position.

The method of claim 1 or 2, wherein determining the parameters for

Spectacle fitting (60A, 60B, 62A, 62B, 63-68) is performed based on the captured 2D image.

The method of claim 3, comprising scaling the 2D image based on the depth information and / or scaling spectacle fitting parameters (60A, 60B, 62A, 62B, 63-68) based on the 2D image based on

Depth information.

The method of claim 3 or 4, further comprising rectifying (84) the 2D image based on the depth information.

The method of any one of claims 1 to 5, wherein acquiring the depth information (80) and / or taking the 2D image (81) is repeated a plurality of times, the method further comprising averaging over a plurality of acquired depth information and / or over a plurality of acquired images includes. The method of claim 6, further comprising discarding (82) 2D images and / or depth information that satisfy predetermined criteria.

Method according to one of claims 1 to 7, further comprising:

 Depicting a model of the head (10) based on the depth information, and

Virtual fitting of glasses to the model,

wherein the eyeglass fitting parameters (60A, 60B, 62A, 62B, 63-68) are determined based on the virtual fitting.

Apparatus for determining spectacle fitting parameters (60A, 60B, 62A, 62B, 63-68) comprising:

 depth information detecting means (12; 40,41) for detecting depth information with respect to a head (10) of a user, the

Depth information comprise at least a distance (14) of the head (10) to the device,

 an evaluation device (13) which is set up the parameters for

Determine eyeglass fitting (60A, 60B, 62A, 62B, 63-68) based on the acquired depth information, and

a 2D camera (20) for taking an image of at least a part of the head (10),

wherein the device is arranged such that the

 Depth information detection device (12) and the 2D camera (20) detect the head (10) via a common optical axis.

Apparatus according to claim 9, wherein the depth information detecting means (12) comprises a light field camera.

Device according to one of claims 9 or 10, wherein the

Depth information detecting means (12; 40, 41) based on infrared radiation operates.

Device according to one of claims 9 to 11, wherein the

Depth information detection means (12; 40,41) is arranged to detect a depth profile of a region of interest of the head (10), and wherein the Evaluation device (13) is set up, a three-dimensional model of

indicate the area of interest.

Device according to one of claims 9 to 12, wherein the

Depth information detection device (12; 40, 41) comprises a device based on transit time measurements and / or phase measurements and / or triangulation and / or and / or pattern projection and / or stereo image recording.

A method of determining spectacle fitting parameters (60A, 60B, 62A, 62B, 8) comprising:

 Detecting (70; 80) depth information regarding a user's head (10), the depth information comprising a distance (14) between the user's head (10) and a device used for detection, and determining (72; 85) parameters for spectacle fitting (60A, 60B, 62A, 62B, 63-68) based on depth information, and

 Depicting a model of the head (10) based on the depth information, and virtually fitting glasses to the model,

 wherein the eyeglass fitting parameters (60A, 60B, 62A, 62B, 63-68) are determined based on the virtual fitting.

The method of claim 14, wherein the method further comprises determining a

Head position of the head (10), wherein determining the parameters for

Spectacle fitting (60A, 60B, 62A, 62B, 63-68) is based on the determined head position.

The method of claim 14 or 15, further comprising capturing (71; 81) an image of the head (10), wherein determining the eyeglass fitting parameters (60A, 60B, 62A, 62B, 63-68) is based on the captured image.

The method of claim 16, comprising scaling the image based on

Depth information and / or scaling of spectacle fit parameters (60A, 60B, 62A, 62B, 63-68) based on the image based on the depth information.

The method of claim 16 or 17, further comprising rectifying (84) the image based on the depth information.

The method of any of claims 14 to 18, wherein acquiring the depth information (80) and / or taking an image (81) is repeated a plurality of times, the method further comprising averaging over a plurality of acquired depth information and / or over a plurality of acquired images includes.

The method of claim 19, further comprising discarding (82) images and / or depth information that satisfy predetermined criteria.