Robust and consistent defect size measuring method in Automated Vision Inspection system

Automatic vision inspection (AVI) systems automatically detect defect features and measure their sizes via camera vision. AVI systems usually report different measurements on same defect with some variations on position or rotation mainly because we get different image. It is caused by possible variations from image acquisition process including optical factors, non-uniform illumination, random noises, and so on. For this reason, conventional area based defect measuring method has a problem on robustness and consistency. In this paper, we propose a new defect size measuring method to overcome this problem. We utilize volume information which is completely ignored in the area based defect measuring method. We choose a cylinder shape as a defect model for experiment. The results show that our proposed method dramatically improves robustness and consistency of defect size measurement. Given proper modeling, the proposed volume based measuring method can be applied to various types of defect.