Online Stereo Measurement System for a Sand Mold

A stereo camera method for 3D shape measurement is widely used in various fields. The reason is that the method can obtain 3D data of a shape of an object within very short time without contact with the object. But search process for finding a stereo pair image takes much time, and it is the weakest point of the method. If we can estimate an area where one of the pair image exists, stereo search can be performed quickly and total time for a 3D shape reconstruction is shortened. In this paper we apply the stereo method to a sand mold measurement. In order to realize fast searching, we propose using a CAD model of a metal mold for the sand mold. The experimental results show that a flat part of the mold is reconstructed within 500 msec with the accuracy of 10 mum. On the other hand, the simulation results show that two sets of the stereo camera are needed to reconstruct a cylindrical part within the required accuracy