Method for measuring spectacle frames using an optical recording device and use of a mobile optical recording device for measuring spectacle frames

Abstract

The invention relates to a method for measuring spectacle frames using a mobile optical recording device, in which data known to the user, for example the frame width (A-size) and / or frame height (B-size) of the spectacle frame, are used to determine the centration data of the spectacle lenses of a test subject. According to the invention, a sequence of images of a predetermined change in head posture and / or head movement is recorded by means of the mobile optical recording device of the test subject with the spectacle frame to be measured on his head, in which a distance to be measured in one half of the frame is located on the object plane perpendicular to the optical axis of the camera.Subsequently, from the image sequence, using the known lens mount width (A-Size) and / or lens mount height (B-Size) of the right and / or left lens mount half, a scale in pixels per mm is determined as a basis for determining the centering data by selecting those individual images in which the distances to be measured of the lens mount width (A-Size) and / or the lens mount height (B-Size) each reach the maximum value.

Description

Prior ArtThe invention is based on a method for measuring spectacle frames with a mobile optical recording device, in which data known to the user, for example the frame width (A-size) and / or frame height (B-size) of the spectacle frame, are used for determining centering data of the spectacle lenses of a test person, according to the preamble of claim 1 and the use of a mobile optical recording device for measuring spectacle frames according to the preamble of claim 15.Methods for measuring spectacle frames with mobile terminals, e.g. tablets, are known. Thus, for example, a mobile video centering system for determining centering data for spectacle lenses consists of a tablet PC which has a display, a position sensor and a high-resolution image capturing device with an optical attachment in which a periscope with deflection mirrors is arranged (DE 20 2016 000 170 U1). A likewise known centering device for determining optical centering parameters of a spectacle wearer has a fixation target which is fastened to a column-like housing and generates a two-dimensionally extended light field at a measurement site for illuminating at least one eye of the spectacle wearer. A measuring device consisting of two image recording devices arranged vertically one above the other serves for ascertaining at least one measuring position of the at least one eye of the spectacle wearer when viewing the light field generated by the fixation target. A correction device acquires information about a deviation of the light field generated at the measurement site from a light field predetermined at the measurement site, and a parameter calculation device determines at least one of the optical centering parameters to be determined on the basis of the determined desired position of the at least one eye (WO 2013 / 104353 A1).Furthermore, a device for measuring the parameters necessary for adapting optical lenses to a spectacle frame with respect to the spectacle frame is known, which device has a camera, which can be oriented with respect to the head for recording the head of the person wearing the spectacle frame, an electronic image processing for determining the parameters from the recording of the head at a specific measurement distance between the head and the camera and an optical coincidence range finder integrated into the camera, which in turn has an optical system arranged downstream of the lens of the camera for dividing the image into four images or partial images lying next to one another. The correct measurement distance is reached when the images or partial images are combined to form a single image (DE 43 23 384 C2).A method for determining centering data for spectacles which are required for grinding the lenses is also known. For this purpose, at least two views of the head of a person wearing a spectacle frame are recorded simultaneously via at least three mirrors. The ascertained centering data are evaluated in a computing unit (DE 10 2008 004 921 A1).The disadvantage of these methods and devices is that they require a specific equipment for measuring spectacle frames, such as camera columns, stereo recording devices, lidar technology, tablet PC with attachment optics or specific system calibrations, which is relatively complicated and expensive.The object of the invention is to develop a simplified method for measuring spectacle frames. Furthermore, it is intended that more easily manipulated terminals can be used for measuring spectacle frames.The object is achieved according to the invention by a method having the features according to claim 1 and by the use of a mobile optical recording device having the features according to claim 15.The Invention and its AdvantagesAccording to the invention, the test person with the spectacle frame to be measured placed thereon records an image sequence of a change in the head position and / or head movement to be specified by means of the mobile optical recording device. Subsequently, from the image sequence, with the aid of the known frame slice width (A-size) and / or frame slice height (B-size) of the right and / or left frame half, a scale in pixels per mm is determined as a basis for the determination of the centering data by selecting those individual images at which the distances of A-size and / or B-size to be measured each reach the maximum value.This makes it possible to measure and / or calibrate spectacle lenses only with a short video sequence recorded by a mobile terminal, for example a smartphone, and an additional lateral recording of the test subject. Instead of the video sequence, it is also possible to record individual images of the test subject.Furthermore, no scaling auxiliary elements, e.g. sighting gauges, and no specific equipment, such as camera columns, stereo recording devices, lidar technology, tablet PC with attachment optics or specific system calibrations are required.In an advantageous embodiment of the invention, the different head postures are predefined by head inclination downwards and / or upwards and by head rotation to the right and / or left.In an embodiment of the invention which is advantageous in this regard, the respective specific head postures, in which, for example, the left half of the frame is aligned both horizontally and vertically perpendicular to the viewing direction of the camera, are achieved in that the subject is requested by the system operator, for example the ophthalmic optician, to assume a corresponding posture, wherein, in this direct response of the subject, instead of the video sequence, individual images can also be recorded and evaluated.In a likewise advantageous embodiment of the invention, a natural posture of the head and / or body is taken by the test person at the beginning and at the end of the video sequence.In a particularly advantageous embodiment of the invention, for determining the lens height (B-size) of the frame from the video sequence, those individual images of the right and left half of the frame are determined in which the distance corresponding to the lens height (B-size) between a horizontal line X applied to the upper inner edge of the frame and a horizontal line Y applied to the lower inner edge of the frame reaches a maximum value and in the process the distance to be measured is located on the object plane perpendicular, i.e. 90 degrees to the optical axis of the camera.In an embodiment of the invention which is advantageous in this regard, the mounting disk height (B-size) in mm is determined from the aforementioned distance to be measured and from a scale in pixels per mm.In a further advantageous embodiment of the invention, those individual images of the right and left frame half are determined from the video sequence in order to determine the pretilt angle, in which the subject assumes a natural head and posture.According to a likewise advantageous embodiment of the invention, the distance between the lines X and Y determined in the case of natural head and body posture is used to determine the pretilt angle in degrees.According to an advantageous embodiment of the invention in this respect, the pretilt angle is determined by triangulation from the different distances between the lines X and Y.According to another advantageous embodiment of the invention, the above-described image sequence generated according to the invention for determining the scale is used for determining the frame angle, and the frame angle is determined from that distance of the other frame half, i.e. that which is not used for determining the scale, which exists between a vertical line A' applied to the inner edge of this frame half and a vertical line B' applied to the outer edge of this frame half.According to an advantageous embodiment of the invention in this respect, the mounting disk angle is determined trigonometrically from the different distances between the lines A and B, i.e. the mounting disk width (A-size), the lines A' and B'.In a likewise advantageous embodiment of the invention, a live image of a level is displayed on the monitor of the smartphone. This facilitates the operator to align the camera of the smartphone in the horizontal, i.e. horizontal direction.In addition, the object of the invention is also achieved by the use of a mobile optical recording device for measuring spectacle frames. In this case, data known to the user, for example the frame width (A-size) and / or frame height (B-size) of the frame, are used to determine centering data of the spectacle lenses of a test person. According to the invention, a smartphone is used as the mobile optical recording device, with which a sequence of images of a change to the head posture and / or head movement to be specified is recorded by the test person with the spectacle frame to be measured placed, In this sequence of images a distance to be measured in a half of the frame is located on the object plane perpendicular, that is to say 90 degrees to the optical axis of the camera of the smartphone. Subsequently, from the image sequence, with the aid of the known frame slice width (A-size) and / or frame slice height (B-size) of the right and / or left frame half, a scale in pixels per mm is determined as a basis for the determination of the centering data by selecting those individual images in which the distances to be measured of the frame slice width (A-size) and / or of the frame slice height (B-size) each reach the maximum value.Further advantages and advantageous embodiment of the invention can be derived from the following description, the claims and the drawings.DRAWINGA preferred exemplary embodiment of the method according to the invention is illustrated in the drawing and is explained in more detail below. FIG. 1 shows a single image of a spectacle frame taken from an image sequence.DESCRIPTION OF THE EMBODIMENTSThe image of a spectacle frame shown in FIG. 1 was taken from an image sequence recorded with a smartphone. Reference lines for the frame width (A-size) and frame height (B-size) are blended into the image, the frame width (A-size) being characterized by vertical lines A and B arranged on the inner and outer edges of the spectacle frame, and the frame height (B-size) by horizontal lines X and Y arranged on the upper and lower edges of the spectacle frame. The vertical lines A, B and horizontal lines X, Y drawn at the left half of the frame form a left box system, and the vertical lines A', B' and horizontal lines X', Y' drawn at the right half of the frame form a right box system. Due to the somewhat greater distance of the right box system of the spectacle frame from the camera of the smartphone, the optically detectable frame width (A-size) appears somewhat smaller than that of the left box system, which can be determined at the smaller distance of the vertical lines A' and B' at the left and right edge of the right frame half of the spectacle frame.Example of specific recording situation of the video sequence and the fixed image:Distance operator, e.g. ophthalmic optician-proband: about 1 mRecording the following video sequences (viewing direction of the test subject always aligned directly with the camera of the smartphone): 1. normal head and posture of the test subject 2. head posture upward 3. head posture again normal 4. head rotation slowly leftward 5. head rotation slowly rightward 6. normal head and posture of the test subject- End of Video Sequence Recordinglateral image recording of the test subject at approximately the same distanceAll features shown here can be essential to the invention both individually and in any combination with one another.

Claims

Method for measuring spectacle frames with a mobile optical recording device, in which data known to the user, for example the frame width (A-size) and / or frame height (B-size) of the spectacle frame, are used for determining centring data of the spectacle lenses of a test person, characterized in that the test person with the spectacle frame to be measured placed records an image sequence of a change in the head position and / or head movement to be specified, in which image sequence a distance to be measured in a frame half is located on the object plane perpendicular to the optical axis of the camera, and then from the image sequence with the aid of the known frame slice width (A-size) and / or frame slice height (B-size) of the right and / or left frame half, a scale in pixels per mm is determined as a basis for the determination of the centering data by selecting those individual images in which the distances to be measured of the frame slice width (A-size) and / or the frame slice height (B-size) each reach the maximum value.Method according to Claim 1, characterized in that the image sequence is recorded as a video sequence.Method according to claim 1, characterised in that the image sequence is recorded as a sequence of individual images.Method according to Claim 1, 2 or 3, characterized in that the different head postures are predefined by head inclination downwards and / or upwards and by head rotation to the right and / or left.Method according to claim 4, characterised in that the respective specific head postures, in which for example the left half of the frame is aligned both horizontally and vertically perpendicular to the viewing direction of the camera, are achieved in that the subject is requested by the system operator to assume a corresponding posture, wherein in this direct response of the subject instead of the video sequence individual images can also be recorded and evaluated.Method according to one of Claims 1 to 5, characterized in that a natural head and / or posture is taken by the test person in each case at the start and at the end of the video sequence.Method according to Claim 1, characterized in that, in order to determine the lens height (B-size) from the video sequence, those individual images of the right and left half of the lens are determined in which the distance, corresponding to the lens height (B-size), between a horizontal line X applied to the upper inner edge of the lens frame and a horizontal line Y applied to the lower inner edge of the lens frame reaches a maximum value and in the process the distance to be measured is located on the object plane perpendicular to the optical axis of the camera.Method according to Claim 7, characterized in that the mounting disc height (B-size) in mm is determined from the distance determined according to Claim 7 and from the scale determined according to Claim 1.Method according to Claim 1, characterized in that, in order to determine the pretilt angle from the video sequence, those individual images of the right and left frame half are determined in which the subject assumes a natural head and body posture.Method according to Claims 7 and 9, characterized in that, in order to determine the pretilt angle in degrees of the distance determined according to Claim 7 during natural head and body posture, between the horizontal line X applied to the upper inner edge of the spectacle frame and the horizontal line Y applied to the lower inner edge of the spectacle frame according to Claim 7 is used.Method according to claim 10, characterised in that the pretilt angle is determined trigonometrically from the different distances between the lines X and Y according to claim 7.Method according to Claim 1, characterized in that the image sequence generated in method step 2 of Claim 1 for determining the scale is used for determining the mount disc angle, and the mount disc angle is determined from that distance of the other mount half, that is to say that which is not used for determining the scale according to Claim 1, which exists between a vertical line A' applied to the inner edge of this mount half and a vertical line B' applied to the outer edge of this mount half.Method according to Claim 12, characterized in that the mounting disc angle is determined trigonometrically from the different distances between the lines A and B according to Claim 7, that is to say the mounting disc width (A-size), and the lines A' and B' according to Claim 12.Method according to Claim 1, characterized in that a live image of a level is displayed on the monitor of the smartphone for the purpose of aligning the optical axis of the camera of the smartphone in the horizontal direction.Use of a mobile optical recording device for measuring spectacle frames, wherein data known to the user, for example the frame width (A-size) and / or frame height (B-size) of the spectacle frame, are used for determining centering data of the spectacle lenses of a test person, characterized in that a smartphone is used as the mobile optical recording device, with which smartphone an image sequence of a change to the head position and / or head movement to be specified is recorded by the test person with the spectacle frame to be measured placed, in which image sequence a path to be measured in a frame half is located on the object plane perpendicular to the optical axis of the camera of the smartphone, and then from the image sequence with the aid of the known frame slice width (A-size) and / or frame slice height (B-size) of the right and / or left frame half, a scale in pixels per mm is determined as a basis for the determination of the centering data by selecting those individual images in which the distances to be measured of the frame slice width (A-size) and / or the frame slice height (B-size) each reach the maximum value.

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