公开(公告)号：US11808564B2

公开(公告)日：2023-11-07

申请号：US17631542

申请日：2020-08-07

Applicant: Nanjing University of Science and Technology

Inventor： Chao Zuo ,  Wei Yin ,  Qian Chen ,  Shijie Feng ,  Jiasong Sun ,  Tianyang Tao ,  Yan Hu ,  Liang Zhang ,  Jiaming Qian

IPC: G01B11/25

CPC classification number: G01B11/2504 ,  G01B11/2513 ,  G01B11/2527

Abstract: A calibration method for fringe projection systems based on plane mirrors. Firstly, two mirrors are placed behind the tested object. Through the reflection of mirrors, the camera can image the measured object from the front and other two perspectives, so as to obtain 360-degree two-dimensional information of the measured object. The projector projects three sets of phase-shifting fringe patterns with frequencies of 1, 8, and 64. The camera captures the fringe image to obtain an absolute phase map with a frequency of 64 by using the phase-shifting method and the temporal phase unwrapping algorithm. By using the calibration parameters between the projector and the camera, the absolute phase map can be converted into three-dimensional information of the measured object. Then, the mirror calibration is realized by capturing a set of 3D feature point pairs, so that the 3D information from different perspectives is transformed into a unified world coordinate system. The calibration method does not need to artificially fix the feature pattern on plane mirrors, only needs to capture a set of 3D feature point pairs by the camera to directly realize the mirror calibration that it avoids the loss of measurement accuracy and realizes high-precision panoramic three-dimensional measurement.

公开(公告)号：US20220221270A1

公开(公告)日：2022-07-14

申请号：US17631542

申请日：2020-08-07

Applicant: Nanjing University of Science and Technology

Inventor： Chao Zuo ,  Wei Yin ,  Qian Chen ,  Shijie Feng ,  Jiasong Sun ,  Tianyang Tao ,  Yan Hu ,  Liang Zhang ,  Jiaming Qian

IPC: G01B11/25

Abstract: A calibration method for fringe projection systems based on plane mirrors. Firstly, two mirrors are placed behind the tested object. Through the reflection of mirrors, the camera can image the measured object from the front and other two perspectives, so as to obtain 360-degree two-dimensional information of the measured object. The projector projects three sets of phase-shifting fringe patterns with frequencies of 1, 8, and 64. The camera captures the fringe image to obtain an absolute phase map with a frequency of 64 by using the phase-shifting method and the temporal phase unwrapping algorithm. By using the calibration parameters between the projector and the camera, the absolute phase map can be converted into three-dimensional information of the measured object. Then, the mirror calibration is realized by capturing a set of 3D feature point pairs, so that the 3D information from different perspectives is transformed into a unified world coordinate system. The calibration method does not need to artificially fix the feature pattern on plane mirrors, only needs to capture a set of 3D feature point pairs by the camera to directly realize the mirror calibration that it avoids the loss of measurement accuracy and realizes high-precision panoramic three-dimensional measurement.

公开(公告)号：US11961244B2

公开(公告)日：2024-04-16

申请号：US17769230

申请日：2020-08-27

Applicant: NANJING UNIVERSITY OF SCIENCE AND TECHNOLOGY

Inventor： Chao Zuo ,  Jiaming Qian ,  Qian Chen ,  Shijie Feng ,  Tianyang Tao ,  Yan Hu ,  Wei Yin ,  Liang Zhang ,  Kai Liu ,  Shuaijie Wu ,  Mingzhu Xu ,  Jiaye Wang

IPC: H04N23/90 ,  G06T3/14 ,  G06T7/33 ,  G06T7/80

CPC classification number: G06T7/337 ,  G06T3/14 ,  G06T7/85 ,  H04N23/90 ,  G06T2207/10012 ,  G06T2207/10028

Abstract: Disclosed is a high-precision dynamic real-time 360-degree omnidirectional point cloud acquisition method based on fringe projection. The method comprises: firstly, by means of the fringe projection technology based on a stereoscopic phase unwrapping method, and with the assistance of an adaptive dynamic depth constraint mechanism, acquiring high-precision three-dimensional (3D) data of an object in real time without any additional auxiliary fringe pattern; and then, after a two-dimensional (2D) matching points optimized by the means of corresponding 3D information is rapidly acquired, by means of a two-thread parallel mechanism, carrying out coarse registration based on Simultaneous Localization and Mapping (SLAM) technology and fine registration based on Iterative Closest Point (ICP) technology. By means of the invention, low-cost, high-speed, high-precision, unconstrained and rapid-feedback omnidirectional 3D real-time molding becomes possible, and a new gate is opened into the fields of 360-degree workpiece 3D surface defect detection, rapid reverse forming, etc.