On-site calibration of line-structured light vision sensor in complex light environments

Significance Statement

Existing calibration methods for a line-structured light vision sensor usually require solving the light plane equation by combining the characteristic points of the target and the image of the light stripe on the target. We propose a novel method for calibration of the line-structured light vision sensor that only requires the image of the light stripe on the target using a movable parallel cylinder target. The main procedure of the proposed method is as follows: the images of the light stripe on the parallel cylinder target are first fitted. The corresponding equations between two ellipses in space and their projected images are then established according to the perspective projection transformation. Given the constraint conditions that the short axis of the ellipse is equal to the diameter of the cylinder, the light plane equation is solved. Finally, the optimal solution of the light plane equation is obtained by nonlinear optimization method. The proposed algorithm is verified by simulation and physical experiments. In the physical experiment, the field of view of the line-structured light vision sensor is about 500 mm×400 mm, and the measurement distance is about 700 mm. When the proposed method is used, a calibration accuracy of 0.07 mm is achieved, which is comparable to that when planar targets are used.

On-site calibration of line-structured light vision sensor in complex light environments. Advances in Engineering

About the author

Zhen Liu received his PH.D degree from Beihang University, Beijing, China, in 2010. He is currently an Associate Professor at the School of Instrumentation Science and Opto-electronics Engineering, Beihang University, Beijing, China. His main research interests include optical measurement, machine vision and image processing. He has published over 30 papers on international journals and conferences including Optics Express, Optics and Lasers in Engineering, Sensors, Measurement science and technology. 

About the author

Xiaojing Li received her master’s degree from Beihang University, Beijing, China, in 2016. During studying for her master degree, she concentrated the research work on optical measurement and machine vision. She published several papers in international journals. 

About the author

Yang Yin received her bachelor’s degree from Beihang University, Beijing, China, in 2014. She is currently a master student at the School of Instrumentation Science and Opto-electronics Engineering, Beihang University. Her main research interests are optical measurement and machine vision.  

Journal Reference

Optics Express, 23,Issue 23,pp. 29896-29911, (2015)

Zhen Liu, Xiaojing Li, Yang Yin

Key Laboratory of Precision Opto-mechatronics Technology, Ministry of Education, Beihang University, No.37 Xueyuan Rd, Haidian District, 100191, Beijing, China.

Abstract

A novel calibration method for the line-structured light vision sensor that only requires the image of the light stripe on the target using a movable parallel cylinder target is proposed in this paper. The corresponding equations between two ellipses obtained from the intersection of the light stripe and the target and their projected images are established according to the perspective projection transformation, and the light plane equation is solved based on the constraint conditions that the minor axis of the ellipse is equal to the diameter of the cylinder. In the physical experiment, the field of view of the line-structured light vision sensor is about 500 mm × 400 mm, and the measurement distance is about 700 mm. A calibration accuracy of 0.07 mm is achieved using the proposed method, which is comparable to that when planar targets are used.

© 2015 Optical Society of America.

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