Abstract The reflective characteristic of mirror surfaces such as a liquid pool surface in arc welding makes many traditional 3D measurement/reconstruction methods fail. The authors proposed to intercept, image, and measure two points in each laser ray reflected from a mirror surface with two diffusive planes and cameras to analytically calculate the equation of the ray. The samples of the points on the mirror surface where the incident laser rays are reflected can thus be analytically calculated as the intersections of the reflection rays with the corresponding incident rays. In this paper, the proposed method is applied to reconstruct the samples on the specular three-dimensional weld pool surface in GTAW (gas tungsten arc welding). Since two diffusive planes are used and must be placed with considerable distance to assure the accuracy of the calculated equations of the reflected rays, focusing reflected laser rays on these two planes becomes an issue. A trade-off among the size of the projected laser pattern, the distances of the arc light with the two diffusive planes, the focus range of the laser rays and the quality of the reflected laser dot images on the diffusive planes has been made to resolve this issue successfully. Further, calibration errors in the locations of the diffusive planes directly affect the accuracy of the calculated equations of reflected rays and an accurate calibration appears to impractical. To resolve this issue, the authors found the least deformation principle and successfully applied it to minimize the calculation errors through calibration rectification. Several weld pool surfaces have been sampled and reconstructed and experimental results verified the effectiveness of the proposed analytical method.
[1]
Radovan Kovacevic,et al.
Real-Time Image Processing for Monitoring of Free Weld Pool Surface
,
1997
.
[2]
Yuming Zhang,et al.
Image processing algorithm for automated monitoring of metal transfer in double-electrode GMAW
,
2007
.
[3]
D. Malacara.
Optical Shop Testing
,
1978
.
[4]
Horst Schreiber,et al.
Phase Shifting Interferometry
,
2006
.
[5]
Yuming Zhang,et al.
Brightness-Based Selection and Edge Detection-Based Enhancement Separation Algorithm for Low-Resolution Metal Transfer Images
,
2009,
IEEE Transactions on Automation Science and Engineering.
[6]
Ruigang Yang,et al.
Measurement of mirror surfaces using specular reflection and analytical computation
,
2013,
Machine Vision and Applications.
[7]
Jianqiang Yi,et al.
Extraction of Three-Dimensional Parameters for Weld Pool Surface in Pulsed GTAW With Wire Filler
,
2003
.
[8]
Yuming Zhang,et al.
Three-dimensional reconstruction of specular surface for a gas tungsten arc weld pool
,
2007
.
[9]
YuMing Zhang,et al.
Gas Metal Arc Weld Pool Surface Imaging: Modeling and Processing
,
2011
.
[10]
Tomás Pajdla,et al.
The geometric error for homographies
,
2003,
Comput. Vis. Image Underst..
[11]
YuMing Zhang,et al.
Observation of a dynamic specular weld pool surface
,
2006
.
[12]
Zhengyou Zhang,et al.
A Flexible New Technique for Camera Calibration
,
2000,
IEEE Trans. Pattern Anal. Mach. Intell..