Patent Publication Number: US-2021181538-A1

Title: Method for measuring the frame wearing parameter and measuring device thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial No. 108145602, filed on Dec. 12, 2019. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of specification. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a method and a device for measuring a frame wearing parameter. 
     Description of the Related Art 
     A frame of sports glasses features with high-curvature wraparound frame. The angles between lens of sports glasses and visual directions are about 15 to 30 degrees. However, astigmatism occurs. Thus, the original prescription is no longer precise. As a result, the parameters of sports glasses need to be calculated via Digital Ray Path (DRP) technology. Then, the correction effect is more precise than the effect only according to prescription. 
     All personal frame wearing parameters can be taken into consideration via the DRP technology to simulate the condition that lens are in front of a user. The more data (such as a back vertex distance (BVD) and pantoscopic tilts) are provided, the better simulation effect can be obtained and gets a better visual effect. However, the frame wearing parameters (such as the back vertex distance and the pantoscopic tilts) usually need a special tool (such as a personization key) for measurement, which is time-consuming and not precise. Moreover, users always feels uncomfortable during the measure process. 
     BRIEF SUMMARY OF THE INVENTION 
     According to the first aspect of the disclosure, a method for measuring a frame wearing parameter is provided. The method includes: scanning a face of a testee wearing a positioning frame to obtain a pupil position, a visual direction, and a 3D face model, the 3D face model wears a positioning frame model corresponding to the positioning frame; superposing a 3D glasses reference model on the positioning frame model of the 3D face model; calculating an inner intersection point between the visual direction and the 3D glasses reference model; and calculating out a back vertex distance according to the pupil position and the inner intersection point and calculate an angle between a lens plane line of the 3D glasses reference model and a space vertical line to regard as a pantoscopic tilt.. 
     According to the second aspect of the disclosure, a device for measuring a frame wearing parameter is provided. The device includes: a 3D image capture device configured to scan a face of a testee wearing the positioning frame from different angles to obtain a plurality of face images; and a computing device electrically connected to the 3D image capture device, the computing device obtains a pupil position, a visual direction, and a 3D face model according to the face images, the 3D face model wears a positioning frame model corresponding to the positioning frame, a 3D glasses reference model is superposed on the positioning frame model of the 3D face model via the computing device, an inner intersection point between the visual direction and the 3D glasses reference model is calculated via the computing device, a back vertex distance is calculated out according to the pupil position and the inner intersection point, and an angle between a lens plane line of the 3D glasses reference model and a space vertical line is calculated to regard as a pantoscopic tilt via the computing device. 
     In sum, the frame wearing parameters, such as a back vertex distance and pantoscopic tilts, are measured automatically in this disclosure, therefore, the measure method and the measure device provided in this disclosure are more efficient than the manual measure way. In addition, when the measure method and the measure device in this disclosure are applied, the testee would not feel uncomfortable in the measure process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing a measure device according to an embodiment. 
         FIG. 2  is a schematic diagram showing positioning of a testee according to an embodiment. 
         FIG. 3  is a schematic diagram showing a testee wearing a positioning frame according to an embodiment. 
         FIG. 4  is a flow chart showing a measure method according to an embodiment. 
         FIG. 5  is a schematic diagram showing a 3D face model according to an embodiment. 
         FIG. 6  is a schematic diagram showing a 3D face model is not superposed on a 3D glasses reference model yet according to an embodiment. 
         FIG. 7  is a schematic diagram showing a 3D face model is superposed on a 3D glasses reference model according to an embodiment. 
         FIG. 8  is a schematic diagram showing a 3D face model with an inner intersection point according to an embodiment. 
         FIG. 9 a    is a schematic diagram showing a 3D face model with a back vertex distance and a pantoscopic tilt viewed from a left side according to an embodiment. 
         FIG. 9 b    is a schematic diagram showing a 3D face model with a back vertex distance and a pantoscopic tilt viewed from a right side according to an embodiment. 
         FIG. 10  is a schematic diagram showing a 3D face model with some frame wearing parameters according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     A back vertex distance is the distance between a cornea and a lens. The angle between a lens surface and a space vertical line is a pantoscopic tilt. The frame wearing parameters, such as the back vertex distance and the pantoscopic tilts, are obtained via a superposing calculation of the 3D face model on the 3D glasses reference model. 
       FIG. 1  is a block diagram showing a measure device according to an embodiment. The device  10  for measuring a frame wearing parameter includes a positioning frame  12 , a 3D image capture device  14 , and a computing device  16 . The positioning frame  12  is worn on a face  20  of a testee  18 . The 3D image capture device  14  is facing to the face  20  of the testee  18 . The 3D image capture device  14  scans the face  20  of the testee  18  wearing the positioning frame  12  from different angles to obtain corresponding face images. The computing device  16  is electrically connected to the 3D image capture device  14  to receive the face images. Then, the computing device  16  performs calculation according to the face images to obtain the frame wearing parameters, such as the back vertex distance or the pantoscopic tilts. In an embodiment, the 3D image capture device  14  and the computing device  16  are independent devices. In an embodiment, the 3D image capture device  14  is a 3D infrared camera, and the computing device  16  is a mobile phone, a notebook, a tablet computer, or a desktop computer, which is not limited herein. In an embodiment, the 3D image capture device  14  and the computing device  16  are integrated in an electronic device. In an embodiment, the 3D image capture device  14  is a 3D infrared camera disposed in the electronic device. In an embodiment, the computing device  16  is a center processing unit (CPU) or a micro-processing device in the electronic device. In some embodiments, the electronic device is a mobile phone, a notebook, a tablet computer, or a desktop computer, which is not limited herein. 
       FIG. 2  is a schematic diagram showing positioning of a testee according to an embodiment.  FIG. 3  is a schematic diagram showing a testee wearing a positioning frame according to an embodiment. Please refer to  FIG. 1  and  FIG. 3 , before the frame wearing parameter is measured, the testee  18  wears the positioning frame  12  in front of the 3D image capture device  14 . The positioning frame  12  includes four colored positioning marks  22 —two center positioning marks  221 ,  222  located at the center of the nose pads of the positioning frame  12 , respectively, one left positioning mark  223  and one right positioning mark  224  (the left side and the right side of the testee) located at two sides of the positioning frame  12 . In an embodiment, the 3D image capture device  14  is disposed on a rotatable stand  24 . A motor device  26  is connected to the rotatable stand  24  to drive the rotatable stand  24  to rotate the 3D image capture device  14  leftward or rightward by 207 degrees to capture face images from different angles. 
       FIG. 4  is a flow chart showing a measure method according to an embodiment. Please refer to  FIG. 1  to  FIG. 4 , when the testee  18  wearing the positioning frame  12  is in front of the 3D image capture device  14  and ready to be measured, the motor device  26  drives the rotatable stand  24  to rotate the 3D image capture device  14  disposed on the rotatable stand  24  leftward or rightward correspondingly. In step S 10 , the 3D image capture device  14  scans the face  20  of the testee  18  and the positioning frame  12  on the face  20  from different angles in sequence to obtain face images. The face images are transmitted to the computing device  16 . The computing device  16  receives the face images and has a calculation to obtain two pupil positions, two visual directions, and a 3D face model  28 . As shown in  FIG. 5 , the 3D face model  28  wears the positioning frame model  30  corresponding to the positioning frame  12 . 
     Then, the computing device  16  executes the superposing step. As shown in  FIG. 6  and  FIG. 7 , a 3D glasses reference model  32  is superposed on the positioning frame model  30  of the 3D face model  28  (step S 12 ). Since the positioning frame  12  includes the center positioning marks  221 ,  222 , the left positioning mark  223 , and the right positioning mark  224 , the positioning frame model  30  on the 3D face model  28  also includes the center positioning marks  221 ′, 222 ′, the left positioning mark (not shown), and the right positioning mark  224 ′. The 3D glasses reference model  32  is fully superposed on the positioning frame model  30  according to the center positioning marks  221 ′,  222 ′, the left positioning mark (not shown) and the right positioning mark  224 ′ and a 4 points iterative closet point (ICP) algorithm. In an embodiment, the 3D glasses reference model  32  further includes a frame reference model  321  and a lens reference model  322 . In an embodiment, in the superposing step, the whole 3D glasses reference model  32  (including the frame reference model  321  and the lens reference model  322 ) is directly superposed on the positioning frame model  30 . In an embodiment, in the superposing step, the computing device  16  first superposes the frame reference model  321  on the positioning frame model  30  of the 3D face model  28  according to the positioning marks  22 ′, and then superposes the lens reference model  322  on the frame reference model  321 . 
     As shown in  FIG. 1 ,  FIG. 4 ,  FIG. 7 , and  FIG. 8 , the computing device  16  calculates two visual directions (the direction of the arrows from eyes shown in  FIG. 7 ) of the 3D face model  28  and two inner intersection points A L , A R  (step  14 ) of the 3D glasses reference model  32 . That is, two inner intersection points A L , A R  are cross points between the visual directions of the 3D face model  28  and inner sides of the lens of the lens reference model  322 . Two inner intersection points A L , A R  include the left inner intersection point A L  and the right inner intersection point A R . 
     As shown in  FIG. 1 ,  FIG. 4 ,  FIG. 8 ,  FIG. 9 a   , and  FIG. 9 b   , the computing device  16  calculates out back vertex distances D L , D R  according to the pupil positions and inner intersection points A L , A R , and then calculates the angle between the lens plane lines L L , L R  of the 3D glasses reference model  32  and a space vertical line L S , respectively, to regard as pantoscopic tilts θ L , θ R  (step S 16 ). The lens plane lines L L , L R  of the 3D glasses reference model  32  are pre-defined. The pupil positions include a left pupil position and a right pupil position, and thus the inner intersection points include the left inner intersection point A L  and the right inner intersection point A R . The left back vertex distance D L  is calculated according to the distance between the left pupil position and the left inner intersection point A L . The right back vertex distance D R  is calculated out according to the distance between the right pupil position and the right inner intersection point A R . The 3D glasses reference model  32  includes the left lens plane line L L  and the right lens plane line L R . A left pantoscopic tilt θ L  is obtained by calculating the angle between the left lens plane line L L  and the space vertical line L S . A right pantoscopic tilt θ R  is obtained by calculating the angle between the right lens plane line L R  and the space vertical line L S . 
     In an embodiment, the left lens plane line L L  is a perpendicular line of the left inner intersection point A L  on the lens reference model  322 . The right lens plane line L R  is a perpendicular line of the right inner intersection point A R  on the lens reference model  322 . 
     After the frame wearing parameters (the back vertex distances D L , D R  and the pantoscopic tilts θ L , θ R ) are obtained, as shown in  FIG. 10 , the most proper glass for the testee is formed according to the frame wearing parameters, such as a pupil distance D 1 , an eye distance D 2 , a nose distance D 3 , a face width D 4 , and a head width D 5 . Consequently, the vision correction effect is good. 
     In sum, the frame wearing parameters, such as a back vertex distance and pantoscopic tilts, are measured automatically in this disclosure, therefore, the measure method and the measure device provided in this disclosure are more efficient than the manual measure way. In addition, when the measure method and the measure device in this disclosure are applied, the testee would not feel uncomfortable in the measure process. 
     Although the present invention has been described in considerable detail with reference to certain preferred embodiments thereof, the disclosure is not for limiting the scope of the invention. Persons having ordinary skill in the art may make various modifications and changes without departing from the scope. Therefore, the scope of the appended claims should not be limited to the description of the preferred embodiments described above.