Visualization of subtle defects of car body outer panels

In the development of press dies especially for outer panels in the automotive industry, the cycle of the press panel inspection and the die modification process is about one month. Car body die makers are trying to reduce the inspection and modification cycle time. Defects of pressed panels are important inspection items for die makers. Subtle defects on un-painted panels are difficult to find and measure even for skilled workers. This paper presents a method to visualize the subtle defects of car body outer panels from the 3D scan data. First, curvature estimation methods for the 3D scan data are devised and experimented. Second, measures to find defect regions from the curvature map are also devised and verified. Several examples are presented.