An optimization solution of a laser plane in vision measurement with the distance object between global origin and calibration points.

Guan Xu,Lina Sun,Zhaobing Hao,Jian Su,Huanping Liu,Xiaotao Li

doi:10.1038/srep11928

Abstract

Equation construction of a laser plane demonstrates a remarkable importance for vision measurement systems based on the structured light. Here we create a simple 1D target with a cone at the bottom and a checkered pattern on the top to calibrate the equation of the laser plane in the view field of a camera. A group of 2D coordinates of the intersection points are extracted from the images with the 1D target at different positions. The objective function is constructed to optimize the coefficients of the laser plane by minimizing the difference between the distance from the feature point to the the origin point and the length of the 1D target. The projective lines of the optimized laser plane on the 3D calibration board overlap the real intersection lines in the experimental images. Finally, the comparison work about the influences of the non-Gaussian noise and point number is investigated experimentally. The experiments show that the method of the distance optimal object from the feature point to the origin point provides an accurate and robust calibration for the laser plane in structured light measurement.

Highlights

Equation construction of a laser plane demonstrates a remarkable importance for vision measurement systems based on the structured light
As the measurement precision relies on the calibration result of the laser plane, determining the accurate equation of a laser plane in the world coordinate system is meaningful to the vision measurement system adopting structured light
The bottom of the 1D target coincides with the origin point of the world coordinate system.The laser plane passes through the center of checkered pattern on the top of the target

Summary

Calibration Process

In the process of vision measurement based on structured light, we need to globally calibrate the laser plane equation to achieve the position and posture of laser plane in the world coordinate system. It is realized that the laser plane equation is solved by the optimization object of the distance from the origin point to a center of checkered pattern on the top of the 1D target in the world coordinate system. The apex of the conical bottom of the 1D target is set at the origin point of the 3D calibration board.The laser plane passes through the center of the checkered pattern on the top of the 1D target by adjusting the position of the top of the 1D target in the view filed of the camera. According to the object that the distance from the feature point to the the origin point of the 3D calibration board is equal to the length of the 1D target, the laser plane equation in the world coordinate system is solved by optimizing the objective function

Construction and Solution of Calibration Model

Experiments and Discussions

Conclusions

Additional Information