3D Profile measurement using a multi-gray scale compared with reference projections

Abstract

Using a three dimensional measurement system with a gray code projection, this paper proposes a novel technique for improving the reliability of the space encoding method. This space encoding method can measure a colored object under a normal illuminated environment. The measurement space is separated into 256 sub-spaces by four gray level patterns. These patterns are projected by a liquid crystal display projector, and are observed by a CCD camera. When the measurement area is 160 mm × 130 mm, the measurement accuracy of this system is approximately 0.5 mm, and the standard deviation is 0.35 mm in a dark room environment and 0.39 mm in a normal illuminated environment. It is shown that this method can be used to measure a colored object by measuring a colored plaster figure in a dark room environment and under a normal illuminated environment.