Surface Defects Detection Method of Metal Cylinder Surface Based on Improved Photometric Stereo
Automatic surface defects detection of metal cylinder is urgently demanded in industrial production.In order to solve the problem that it is difficult to detect uneven defects such as scratches,pits and bumps on cylinder surface,a surface de-fects detection method of metal cylinder surface based on improved photometric stereo is proposed in this paper.Firstly,aiming at the problem that line scan camera is difficult to acquire images illuminated in multi-angle at the same position.A cylindrical multi-angle illuminating image acquisition method is proposed.Trigger signals are used to coordinate the camera acquisition with the orderly change of illuminant.Different lighting conditions are separated from line scan data to form multiple images.Secondly,in view of the calibration error of light source caused by non-Lambert reflection of metal surface,a method based on bilateral filter-ing and Retinex is proposed to suppress specular reflection component,which greatly improves the calculation accuracy of the sur-face normal vector.Meanwhile,the prior knowledge of illuminant irradiation direction is fully used to speed up calculation.Finally,defect areas are extracted and detected based on the object topography information.The experiments show that optimized method in this paper can effectively improve the speed and accuracy of photometric stereo,as well as increase the capability of detecting scratches,pits and bumps defects on cylindrical surface.
万方数据
维普
