Calibration method for fringe projection systems based on plane mirrors

US11808564B2 · kind B2 · utility

Assignee

• NANJING UNIVERSITY OF SCIENCE AND TECHNOLOGY · CN

Inventors

• Chao Zuo · Nanjing, CN
• Wei Yin · Adelaide, AU
• Qian Chen · San Jose, US
• Shijie Feng · Nanjing, CN
• Jiasong Sun · Nanjing, CN
• Tianyang Tao · Nanjing, CN
• Yan Hu · Zhejiang, CN
• Liang Zhang · Beijing, CN
• Jiaming Qian · Nanjing, CN

Key dates

• Filing date: Aug 7, 2020
• Grant date: Nov 7, 2023
• Expiry date: Aug 16, 2040

Classification

• Technology area (CPC G): Physics
• CPC primary: G01B11/2527
• WIPO field: Measurement
• WIPO sector: Instruments

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 …