In three dimensional measurement system using the gray code projection, this paper proposes the technique for improving the reliability of the space encoding method. This space encoding method can measure the object under the illumination, the colored surface of object. The measurement space is encoded to 256 spaces by four gray level patterns. These patterns are projected by liquid crystal color projector, and are taken by CCD camera. When measurement area is 160 mm × 130 mm, measurement accuracy of this system is 1 mm, and the standard deviation is 0.41 mm in the horizontal cross-section, 0.34 mm in the vertical cross-section. It is shown that this method can measure colored object, by measuring the colored plaster figure in the dark and under the illumination.
