# US 10,502,557 B2 · Method for the three dimensional measurement of a moving objects during a known movement > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,502,557 B2 - Document ID: US10502557B2 - Status: Granted - Kind: B2 - Application number: 16/224,693 - Filed: 2018-12-18 - Published: 2019-05-02 - Granted: 2019-12-10 - Earliest claimed: 2016-06-20 - Assignees: Cognex Corporation - Applicants: Cognex Corporation; Cognex Enshape GmbH - Inventors: Bastian Harendt - Web page: https://patentgrep.com/patent/US10502557B2 ## CPC - G01B 11/25: by projecting a pattern, e.g. {one or more lines,} moiré fringes on the object (G01B11/255 takes precedence {; image analysis for depth or shape recovery G06T7/50}) - G01B 11/2522: {the position of the object changing and being recorded} - G01B 11/2545: {with one projection direction and several detection directions, e.g. stereo} - G06T 7/285: using a sequence of stereo image pairs - G06T 7/40: Analysis of texture (depth or shape recovery from texture G06T7/529) - G06T 7/579: from motion - G06T 7/593: from stereo images - G06T 7/97: {Determining parameters from multiple pictures (depth or shape recovery from multiple images G06T7/55; stereo camera calibration G06T7/85)} - G06T 2207/10021: Stereoscopic video; Stereoscopic image sequence - G06T 2207/30241: Trajectory - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract A 3D measurement method including; projecting a pattern sequence onto a moving object; capturing a first image sequence with a first camera and a second image sequence synchronously to the first image sequence with a second camera; determining corresponding image points in the two sequences; computing a trajectory of a potential object point from imaging parameters and from known movement data for each pair of image points that is to be checked for correspondence, The potential object point is imaged by both image points in case they correspond. Imaging object positions derived therefrom at each of the capture points in time into image planes respectively of the two cameras. Corresponding image points positions are determined as trajectories in the two cameras and the image points are compared with each other along predetermined image point trajectories and examined for correspondence; lastly performing 3D measurement of the moved object by triangulation. ## Claims ### Claim 1 A method for three-dimensional measurement of a moving object during a known relative movement between the moving object and a measuring sensor, the method comprising the steps: projecting a pattern sequence of N patterns onto the moving object; capturing a first image sequence of N images by a first camera and capturing a second image sequence of N images that is synchronous to the first image sequence by a second camera; determining corresponding image points in the first image sequence and in the second image sequence; computing a trajectory of a potential object point from imaging parameters of both cameras and from known movement data for each pair of image points of both cameras that is to be checked for correspondence, wherein the potential object point is imaged by both image points in case both image points actually correspond to each other; imaging object positions derived therefrom at each of N capture points in time into image planes respectively of the first camera and of the second camera, wherein positions of the corresponding image points are determined as a first image point trajectory in the first camera and a second image point trajectory in the second camera and the image points are compared with each other along predetermined image point trajectories and examined for correspondence in the captured first and second image sequences; performing three-dimensional measurement of the moving object in a final step from the corresponding image points by triangulation. ### Claim 2 (depends on 1) The method according to claim 1, further comprising the step: comparing the image points along the predetermined first and second image point trajectories by determining a first gray scale sequence from the captured first image sequence of the first camera and a second gray scale sequence from the captured second image sequence of the second camera and determining a similarity of the first gray scale sequence and the second gray scale sequence. ### Claim 3 (depends on 2) The method according to claim 2, wherein determining the similarity of the first gray scale sequence and the second gray scale sequence includes using a standardized cross correlation, a sum of absolute differences, a phase processing or a comparable known measure of similarity for determining a correlation of gray scale sequences. ### Claim 4 (depends on 1) The method according to claim 1, wherein a sequence of static patterns is used as the projected sequence of N patterns. ### Claim 5 (depends on 1) The method according to claim 1, wherein a sequence of phase shifted sine shaped stripe patterns is used as the projected sequence of N patterns. ### Claim 6 (depends on 1) The method according to claim 1, wherein a static pattern is used as the projected sequence of N patterns, and wherein a projection of the static pattern onto the moving object is adjusted at will with respect to position or shape. ### Claim 7 An apparatus for three-dimensional measurement of a moving object during a known relative movement between the moving object and a measuring sensor, the apparatus comprising a processor in communication with memory, the processor being configured to execute instructions stored in the memory that cause the processor to perform a method comprising the steps: causing a projector to project a pattern sequence of N patterns onto the moving object; causing a first camera to capture a first image sequence of N images and a second camera to capture a second image sequence of N images that is synchronous to the first image sequence; determining corresponding image points in the first image sequence and in the second image sequence; computing a trajectory of a potential object point from imaging parameters of both cameras and from known movement data for each pair of image points of both cameras that is to be checked for correspondence, wherein the potential object point is imaged by both image points in case both image points actually correspond to each other; imaging object positions derived therefrom at each of N capture points in time into image planes respectively of the first camera and of the second camera, wherein positions of the corresponding image points are determined as a first image point trajectory in the first camera and a second image point trajectory in the second camera and the image points are compared with each other along predetermined image point trajectories and examined for correspondence in the captured first and second image sequences; performing three-dimensional measurement of the moving object in a final step from the corresponding image points by triangulation. ### Claim 8 (depends on 7) The apparatus according to claim 7, further comprising the step: comparing the image points along the predetermined first and second image point trajectories by determining a first gray scale sequence from the captured first image sequence of the first camera and a second gray scale sequence from the captured second image sequence of the second camera and determining a similarity of the first gray scale sequence and the second gray scale sequence. ### Claim 9 (depends on 8) The apparatus according to claim 8, wherein determining the similarity of the first gray scale sequence and the second gray scale sequence includes using a standardized cross correlation, a sum of absolute differences, a phase processing or a comparable known measure of similarity for determining a correlation of gray scale sequences. ### Claim 10 (depends on 7) The apparatus according to claim 7, wherein a sequence of static patterns is used as the projected sequence of N patterns. ### Claim 11 (depends on 7) The apparatus according to claim 7, wherein a sequence of phase shifted sine shaped stripe patterns is used as the projected sequence of N patterns. ### Claim 12 (depends on 7) The apparatus according to claim 7, wherein a static pattern is used as the projected sequence of N patterns, and wherein a projection of the static pattern onto the moving object is adjusted at will with respect to position or shape. ### Claim 13 A non-transitory computer-readable storage medium storing instructions for three-dimensional measurement of a moving object during a known relative movement between the moving object and a measuring sensor that, when executed by a processor, cause the processor to perform a method comprising the steps: projecting a pattern sequence of N patterns onto the moving object; capturing a first image sequence of N images by a first camera and capturing a second image sequence of N images that is synchronous to the first image sequence by a second camera; determining corresponding image points in the first image sequence and in the second image sequence; computing a trajectory of a potential object point from imaging parameters of both cameras and from known movement data for each pair of image points of both cameras that is to be checked for correspondence, wherein the potential object point is imaged by both image points in case both image points actually correspond to each other; imaging object positions derived therefrom at each of N capture points in time into image planes respectively of the first camera and of the second camera, wherein positions of the corresponding image points are determined as a first image point trajectory in the first camera and a second image point trajectory in the second camera and the image points are compared with each other along predetermined image point trajectories and examined for correspondence in the captured first and second image sequences; performing three-dimensional measurement of the moving object in a final step from the corresponding image points by triangulation. ### Claim 14 (depends on 13) The non-transitory computer-readable storage medium according to claim 13, further comprising the step: comparing the image points along the predetermined first and second image point trajectories by determining a first gray scale sequence from the captured first image sequence of the first camera and a second gray scale sequence from the captured second image sequence of the second camera and determining a similarity of the first gray scale sequence and the second gray scale sequence. ### Claim 15 (depends on 14) The non-transitory computer-readable storage medium according to claim 14, wherein determining the similarity of the first gray scale sequence and the second gray scale sequence includes using a standardized cross correlation, a sum of absolute differences, a phase processing or a comparable known measure of similarity for determining a correlation of gray scale sequences. ### Claim 16 (depends on 13) The non-transitory computer-readable storage medium according to claim 13, wherein a sequence of static patterns is used as the projected sequence of N patterns. ### Claim 17 (depends on 13) The non-transitory computer-readable storage medium according to claim 13, wherein a sequence of phase shifted sine shaped stripe patterns is used as the projected sequence of N patterns. ### Claim 18 (depends on 13) The non-transitory computer-readable storage medium according to claim 13, wherein a static pattern is used as the projected sequence of N patterns, and wherein a projection of the static pattern onto the moving object is adjusted at will with respect to position or shape.