An Image Self-Calibration Method Based on Parallel Laser Ranging

doi:10.16183/j.cnki.jsjtu.2021.447

Abstract

Abstract:

Regarding the disadvantages of existing camera calibration methods, such as external information relative, special camera poses,the need for calibration targets, and complex operations, this paper proposes a real-time self-calibration method based on parallel laser ranging by employing high-precision laser rangefinders to synchronously measure the position of the measured object plane when taking pictures, so that the object plane equation can be solved. The 2D coordinates of at least four sets of corresponding points on object plane and image planes are selected to obtain the homography matrix, which represents the mapping relationship between object and image planes, so as to complete the calibration simply and quickly. A calibration device is developed to validate the accuracy of the proposed self-calibration method in different testing scenarios. The results show that the measurement error of line segments length in the image are between -0.49% and 0.15%, and the average errors are merely -0.14%, which indicates that the parallel laser ranging self-calibration method proposed in this paper is accurate and robust. The causes of measurement error are further investigated by analyzing the influences of laser ranging, laser inclination, and device offset. The error eliminating suggestions are provided to give references for the application of the proposed self-calibration method in the field of image measurement.

Key words: image measurement, self-calibration method, laser ranging, object plane equation, homography matrix

CLC Number:

TP391.4

CHENG Bin, HUANG Bin, LI Derui. An Image Self-Calibration Method Based on Parallel Laser Ranging[J]. Journal of Shanghai Jiao Tong University, 2022, 56(7): 850-857.

Figures/Tables 11

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场景	各点激光测距值/mm
场景	C_L	C_T	C_R
I	245	245	244
II	345	345	344
III	445	446	443
IV	545	545	543
V	645	646	644

线段	场景I		场景II		场景III		场景IV		场景V
线段	测量值/ mm	相对误差/%	测量值/ mm	相对误差/%	测量值/ mm	相对误差/%	测量值/ mm	相对误差/%	测量值/ mm	相对误差/%
l_A₃_A₇	95.857	-0.15	95.610	-0.41	96.088	0.09	96.057	0.06	95.678	-0.34
l_A₄_A₈	95.785	-0.22	95.582	-0.44	95.923	-0.08	96.148	0.15	95.834	-0.17
l_A₅_A₉	95.532	-0.49	95.577	-0.44	95.928	-0.08	96.084	0.09	95.779	-0.23
l_A₆_A₁₀	95.666	-0.35	95.661	-0.35	95.717	-0.29	96.127	0.13	95.984	-0.02
l_A₁_A₂	96.088	0.09	95.978	-0.02	96.027	0.03	95.975	-0.03	95.879	-0.13