The camera is directed at a scene, along with a stripe projector consisting of a thin light source (xenon tube and slit) on the axis of a turntable, and a binary mask conforming to a cylinder coaxial with this. The mask has alternate opaque and transparent stripes parallel to the axis. It forms a sequence in which each sub- sequence of given length n (8 here) is different.

No lens is used in the projector, deliberately smooth- ing the resulting illumination in a shadowing process. In operation, the turntable rotates, and images are taken at uniform angular intervals for several consecu- tive frames. In the consecutive frames, a given pixel records samples of the brightness of a fixed surface point. The vector consisting of those samples, when normalized, is unique to the place in the sequence from which it came, thus enabling the computation, via a fast indexing process, of the 3D position of the surface point. The code is similar to a DeBruijn sequence, but modified to reduce range error. Several types of calibra- tion and error compensation were used to produce an accurate range image.