Method and device for determining centering data

Abstract

Method for determining centering data, in which a. an actual momentary head posture of a test subject is determined, b. an arrangement of a spectacle frame (202) relative to the specific actual instantaneous head position is determined, wherein c. a habitual head posture is determined using an automated procedure and d. the specific actual instantaneous head posture is corrected using the specific habitual head posture, characterized in that the centering data are determined on the basis of the habitual and not the random actual instantaneous head posture, by determining a deviation of the actual instantaneous head posture from the specific habitual head posture for the correction and converting the centering values ​​on the basis of this deviation, wherein the habitual head posture is determined using a dynamic method with the following steps: e. continuous measurement and recording of head posture using a calibrated image recording device in a measurement situation over a period of time when the subject is distracted from the measurement situation, f. Following the measurement, a three-dimensional (3D) model of the head is created as 3D data from the recording, g. Further processing of the 3D data to determine a preferred head position from the recording.

Description

[0001] The invention relates to a method for determining centering data according to the preamble of patent claim 1 and to a device for determining centering data according to the preamble of patent claim 9. Finally, the invention relates to a computer program for carrying out the above-mentioned methods.

[0002] When opticians determine the centration data for the optical adjustment of glasses, i.e. all necessary information for the correct centration of spectacle lenses in a spectacle frame for the individual application of the customer or test subject, the following procedure can be used:

[0003] The customer is asked to adopt the most natural head and body posture possible. The centration values ​​are then determined by marking the visual points in the lens plane of the spectacle frame using a pen or by video recording, followed by manual (e.g., with the video centration device marketed by the applicant under the "Video Infral" trademark) or automated (e.g., with the video centration device marketed by the applicant under the "RV Terminal" trademark) centration data determination.

[0004] To determine the pre-tilt angle, a tool called a "Y-stick" is used. This tool "freezes" the pre-tilt angle of the spectacle frame at a given time so that it can be read off later. The pre-tilt angle thus recorded is then used to position the customer in the same position in front of a centration system.

[0005] Furthermore, EP 1 591 064 A1 discloses a measuring device for determining head inclination, which is marketed by the applicant of EP 1 591 064 A1 under the name "Ysis." This measuring device is attached to the spectacle frame. This proposal aims to record the "normal" head posture at a given time for both near and far vision. The head inclinations assumed when looking into the distance and when reading are used to determine the difference in head inclination between distance and near vision tasks. The corresponding visual points through the spectacle lens are then determined from this.

[0006] All of the above methods are static, ie a “snapshot” of the respective situation is used to determine a habitual head posture.

[0007] WO 2005 / 069063 A1 discloses the measurement of centering data. This assumes that the subject maintains a habitual head posture during the measurement.

[0008] DE 10 2004 045 012 A1 deals with the measurement of the forward tilt angle of a spectacle frame. It is assumed that the test subject adopts a habitual head position during this measurement.

[0009] FR 2 896 682 A1 discloses a device for measuring the angle between two pre-tilt angles of the spectacle frame, namely the pre-tilt angle when looking into the distance and the pre-tilt angle when looking up close.

[0010] WO 01 / 62139 A1 discloses classifying the behavior of a spectacle wearer based on their gaze habits. Typical head and eye movements during various visual tasks are determined. Based on this, the subject's gaze behavior is categorized according to eye and head mobility (head / eye mover). The results of the analysis are used as a basis for selecting a suitable spectacle lens.

[0011] EP 1 747 750 A1 discloses the method for determining the most frequent gaze directions relative to the head. For this purpose, head posture and gaze direction are detected simultaneously. From the determined relative gaze directions, the relative "net" gaze direction and the resulting visual point through a spectacle lens are determined.

[0012] DE 10 2004 063 160 A1 describes a method and device for adjusting eyeglasses, in particular for recording the habitus head posture of a test subject, whose measurement data are incorporated into the video centration data determination. In this method, several video photographs are taken of the test subject to determine the head posture angle of a test subject in various head posture positions. The head posture angles are recorded and compared with the forward tilt angle of the eyeglass frame and the corneal vertex distance. The corresponding video photographs are taken at a moment when, in the opinion of the operator, the test subject has assumed their natural habitus head posture.

[0013] A centration measurement, i.e. a measurement in which all necessary information for the correct centration of spectacle lenses in a spectacle frame for the individual application of the customer or test subject is determined, represents a forced situation for the optician's customer. Although the centration measurement reveals how the customer held his head during a photograph, this head position does not necessarily correspond to his "normal", i.e. most common head position in actually casual situations.

[0014] This remains the same even when the procedure described in DE 10 2004 063 160 A1 is used. Furthermore, this procedure carries the risk that the supposedly natural head position is not recorded at all, but rather a different one, because the test subject has already assumed a different head position within the operator's reaction time.

[0015] The object of the invention is to provide a more precise method for determining centering data and a corresponding device suitable for implementing the method according to the invention. This method uses an improved method for determining the habitual head posture of a subject, specifically such that the determined head posture is closer to the subject's actual "normal" head posture than is the case with the above-described prior art methods.

[0016] The problem is solved by a method having the features of patent claim 1.

[0017] The object is further achieved by a device having the features of patent claim 9.

[0018] Advantageous embodiments and further developments of the invention are the subject of the subclaims.

[0019] The dynamic method used in the invention to determine the habitual head posture of a subject comprises the following method steps: e. continuous measurement and recording of head posture using a calibrated image recording device in a measurement situation over a period of time when the subject is distracted from the measurement situation, f. Following the measurement, creation of a three-dimensional (3D) model of the head as 3D data from the recording, g. Further processing of the 3D data to determine a preferred head posture from the recorded head posture.

[0020] The corresponding device for determining the habitual head posture of the subject comprises in a corresponding manner: e. a recording device for continuously measuring and recording the head posture by means of a calibrated image recording device in a measuring situation over a period of time when the subject is distracted from the measuring situation, f. a device for creating a three-dimensional (3D) model of the head as 3D data from the recording following the measurement, and e. a determination device for further processing the 3D data and determining the preferred head posture from the recorded head posture.

[0021] The method outlined above, or the corresponding device specifically designed to implement this method, prevents the subject's habitual head posture from being mistakenly assumed to be a head posture recorded or determined randomly at a time that does not correspond to their usual head posture, as can be the case with the prior art methods described in the introduction to the description. The problem posed at the outset is therefore fully solved by this method and the corresponding device.

[0022] The assumption of habitual head posture as the preferred head posture determined from a head posture recorded over a certain period of time also makes it possible, for example, to correct the head posture measured during the centration measurement (e.g. using the video centration devices marketed by the applicant under the names Relaxed Vision Terminal and Video Infral), so that the centration data are determined on the basis of the "normal" and not the random head posture.

[0023] The invention comprises a method for determining centering data, in which a. an actual current head position of a subject is determined, b. an arrangement of a spectacle frame is determined relative to the specific actual current head position, c. a habitual head posture is determined using an automated procedure and d. the determined actual momentary head posture is corrected with the aid of the automatically determined habitual head posture, characterized in that the centering data are determined on the basis of the habitual and not the random actual momentary head posture, by determining a deviation of the actual momentary head posture from the determined habitual head posture for the correction and converting the centering values ​​on the basis of this deviation, wherein the habitual head posture is determined using a dynamic method as described above.

[0024] In a corresponding manner, the subject of the invention is a device for determining centering data with a head posture determination device to determine the actual current head posture of the subject, b. a detection device to determine the position of the spectacle frame relative to the specific actual current head position, c. a device for the automated determination of habitual head posture and d. a correction device for correcting the determined actual momentary head posture with the aid of the determined habitual head posture, characterized in that the centering data are determined on the basis of the habitual and not the random actual momentary head posture, by determining a deviation of the actual momentary head posture from the determined habitual head posture for the correction and converting the centering values ​​based on this deviation, wherein the device for determining the habitual head posture is designed as described above.

[0025] The above-mentioned task is fully achieved by such a method or the corresponding device.

[0026] In the method according to the invention for determining the habitual head posture of a test subject, the time period within which the head posture is recorded can be specified. For example, the head posture can only be recorded during the time during which reliable data on the habitual head posture of the test subject can be obtained. The recording of forced and / or unnatural head postures can be avoided. Furthermore, the time period can be individually set so that the recorded data allows a sufficiently reliable statement to be made about the actual habitual head posture. It is advantageous, for example, if only those time periods are selected from the recording to determine the habitual head posture during which the test subject adopted a head and / or body posture that complies with ergonomic principles.

[0027] A preferred head posture is the head posture in which the test subject holds their head with a certain probability when performing a given visual task. Typical values ​​for this probability are, for example, over 30%, over 50%, over 80%, or even over 90% for the specific visual task. Such an analysis can be performed using standard mathematical / statistical methods. Suitable software algorithms can, if necessary, automatically or with user assistance, eliminate extreme values ​​(outliers) from the recorded data set of the habitual head posture before a typical head posture is determined. A selection is then made from the set of these most probable head postures.

[0028] The recorded head position in which the subject is most likely to hold his head can also be selected as the preferred head position.

[0029] Although it is fundamentally possible to allow the test subject to choose the posture and / or what they are looking at when recording their head position, it is often advantageous to assign specific visual tasks. Particularly when head position is incorporated into the lens calculation or the centering of a lens, it is advisable to pay particular attention to the directions of gaze for near and / or far vision. The invention provides, for example, for selecting one of the recorded positions in which the test subject holds their head when looking at near and / or far vision as the preferred head position.

[0030] Furthermore, it is useful to consider the subject's posture. When looking into the distance, a person is more likely to stand, whereas when looking up close, such as when reading, a person prefers to assume a sitting position. The invention therefore provides for selecting one of the recorded positions during which the subject is standing and / or sitting as the preferred head posture.

[0031] Habitual head posture depends to a large extent on the activity of the test subject and the visual impressions they perceive. It is therefore also advantageous to present the test subject with concrete everyday situations and / or everyday visual tasks under which their habitual head posture is to be determined. The advantage of this is that the test subject / customer is distracted from the actual measurement situation and thus does not adopt an unnatural head posture. The visual tasks can consist of the test subject / customer moving freely in the optician's shop, who records the habitual head posture, and, for example, looking at the displays, or following traffic situations that are presented via an electronic medium such as a display, a projector, etc., as described, for example, in US 2007 / 0229761A1, or being asked to read a document. The visual tasks are, for example,chosen so that a typical head posture can be determined while standing and / or sitting. When determining centration data for reading glasses, for example, the habitual head posture while the subject is sitting and reading must be taken into account.

[0032] Specifically, everyday situations or everyday visual tasks at near and / or far distance can be presented to the test subject / customer over a period of time to dynamically determine their habitual head posture. During this time, the head posture, if necessary in combination with the corresponding posture and, if applicable, the (relative) position such as the inclination of the glasses or lenses worn by the test subject, are continuously measured. The measurement is carried out in such a way that the test subject / customer is not affected. Following the measurement, the most common head posture, if recorded, also the corresponding posture and, if applicable, the position, in particular the inclination of the glasses or lenses, can be determined and later taken into account when determining the centration data. In particular, the visual points for near and / or television tasks, the so-called inset and / or the corridor length can be determined. Specifically, for example,The visual point through the lens can be determined from the head position when looking at near and far distances, assuming the position of the visual target is known. If the visual points are known, the size of the inset and the length of the near vision corridor can also be determined. Any difference between head direction and gaze direction can be taken into account when determining the visual points and / or the inset.

[0033] Head posture is recorded using a calibrated image recording device. Such an image recording device could be, for example, a video or digital camera system with a connected automated image analysis system. After creating a three-dimensional (3D) model, the image data is further processed as 3D data. From this data, typical parameters of the glasses, such as forward tilt, side tilt, etc., can also be determined.

[0034] In the method for determining centering data according to the invention, the determined actual current head posture is corrected using the determined habitual head posture in such a way that the centering data is determined based on the habitual and not the random head posture. The correction can be performed, for example, by determining the deviation of the current head posture from the habitual head posture and converting / correcting the centering values ​​based on this deviation.

[0035] The determined habitual head posture of the test subject / customer and the possibly also determined forward tilt angle of the glasses can also be used to force the customer to align for the conventional centration data determination by initiating an automatic triggering of the imaging units when the desired forward tilt angle of the glasses is reached or by giving a signal to the operator that the centration data determination can now take place.

[0036] In particular, the invention also provides that the above-described methods for determining habitual head posture and for determining centering data are available in the form of computer programs with program codes that can be executed on a computer. The computer programs can be stored on a machine-readable data carrier.

[0037] For the sake of completeness, it should be noted that the above-mentioned recording device for recording the head posture over a period of time comprises an image recording device. The image recording device can be designed, for example, as described above. The determination device for determining a preferred head posture from the recording can comprise a computer.

[0038] The head posture determination device for determining the actual current head posture of a subject may comprise a position recording device and / or an image recording device, in particular of the type described above.

[0039] The determination device for determining the arrangement of a spectacle frame relative to the determined actual current head posture can comprise an image recording device, in particular a video or digital camera, and / or a computer.

[0040] The invention will now be described in more detail with reference to the drawings. They show: Fig. 1 a schematic representation of an inventive device for determining centering data with an inventive device for determining the habitual head posture of a subject; Fig. 2 images of a customer's face with adjusted frame in zero gaze direction e. from the front f. from the side g. from the front with centering data, namely x, y i.e. from the side with centration data, namely corneal vertex distance and frame inclination

[0041] Let's assume that a customer visits an optician's shop to purchase new glasses. First, they are advised on the lenses and frames that are suitable for them. After selecting the frame, the actual centration data is determined using a device according to the invention.

[0042] The Fig. 1 shows a device 100 according to the invention for determining centering data. This device 100 for determining centering data comprises a video centering device 110 with a video camera 112 and a computer 114 with a keyboard 116, a screen 118, and a storage medium 120. This is a calibrated system, i.e., a system for recording and determining dimensions.

[0043] The customer's face is recorded with the adjusted frame 202 in the zero viewing direction from the front and from the side with the video camera 112, as shown in the Fig. 2a) and b).

[0044] With the front view shown on screen 118 ( Fig. 2c), the frame shape 202 is first recorded. Furthermore, the pupil centers 204 are determined, e.g., using the coincidence method, relative to the frame shape 202. The lateral image is used to determine the corneal vertex distance HSA and the frame inclination φ to meet the eye rotation point requirement, as shown in Fig. 2d).

[0045] According to the invention, it is now provided to record the habitual head posture and the inclination of the glasses, for example with the help of the calibrated video camera, over a longer period of time and to determine a habitual head posture and a preferred inclination of the glasses from this.

[0046] The head posture thus determined and the associated forward tilt angle of the spectacles as well as other measurement data such as the arrangement of the spectacles in the frame or lens plane in x, y are used to convert the centration data conventionally determined by means of the video centration device 110 (e.g. distance reference point 206, near measuring circle 208), if the customer had adopted a head posture deviating from the normal head posture when determining them (cf. Fig. 2c).

Claims

[1] Method for determining centering data, in which a. an actual current head position of a subject is determined, b. an arrangement of a spectacle frame (202) relative to the determined actual current head posture is determined, wherein c. a habitual head posture is determined using an automated procedure and d. the specific actual current head posture is corrected with the help of the specific habitual head posture, characterized by that the centration data are determined on the basis of the habitual and not the random actual current head posture, by determining a deviation of the actual current head posture from the determined habitual head posture for the correction and converting the centration values ​​on the basis of this deviation, whereby the habitual head posture is determined using a dynamic procedure with the following steps: e. continuous measurement and recording of head posture using a calibrated image recording device in a measurement situation over a period of time when the subject is distracted from the measurement situation, f. Following the measurement, creation of a three-dimensional (3D) model of the head as 3D data from the recording, g. Further processing of the 3D data to determine a preferred head posture from the recording. [2] Method according to claim 1, characterized by that in step c. the inclination (ϕ) of the spectacle frame (202) is also determined. [3] Method according to claim 1 or 2, characterized by that the time period is specified. [4] Method according to one of claims 1 to 3, characterized by that the recorded position in which the subject is most likely to hold his head during a given visual task is chosen as the preferred head position. [5] Method according to one of claims 1 to 4, characterized by that the preferred head posture is one of the recorded postures in which the test subject holds the head when looking close up and / or when looking into the distance and / or that the preferred head posture is one of the recorded postures in which the test subject is standing and / or sitting. [6] Method according to one of claims 1 to 5, characterized by that the test subject is presented with everyday situations and / or everyday visual tasks. [7] Method according to one of the preceding claims, characterized by that the determined actual momentary head posture is corrected with the help of the determined habitual head posture in such a way that the centering data (ϕ, x, y) are determined on the basis of the habitual and not the random actual momentary head posture. [8] Method according to claim 7, characterized bythat the determined actual current head posture is corrected with the help of the determined habitual head posture by determining the deviation of the current head posture from the habitual head posture and using this to convert the centering values. [9] Device (100) for determining centering data with a head posture determining device (110) for determining an actual current head posture of a subject, b. a determining device (114) for determining an arrangement of a spectacle frame relative to the determined actual current head posture, c. a device (110) for automatically determining the habitual head posture and d. a correction device (114) for correcting the determined actual current head posture with the aid of the determined habitual head posture, characterized bythat the centration data are determined on the basis of the habitual and not the random actual current head posture, by determining a deviation of the actual current head posture from the determined habitual head posture for the correction and converting the centration values ​​on the basis of this deviation, wherein the device for determining the habitual head posture e. a recording device (110) for continuously measuring and recording the head posture by means of a calibrated image recording device in a measuring situation over a period of time when the subject is distracted from the measuring situation, f. a device for creating a three-dimensional (3D) model of the head as 3D data from the recording following the measurement, and g. a determination device (114) for further processing the 3D data and determining a preferred head posture from the recording. [10] Device according to claim 9, characterized by that the recording device (110) comprises a position recording device and / or an image recording device (112) attachable to the head of the subject. [11] Device according to claim 9 or 10, characterized by that the detection device comprises a computer (114). [12] Computer program with program code for carrying out the method according to one of claims 1 to 8, when the program is executed in a computer (114) of a device (100) according to one of claims 9 to 11. [13] Computer program according to claim 12, stored on a machine-readable data carrier (120).

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