Real-time structured light patterns coding with subperfect submaps

Coded structured light is a technique that allows the 3-D reconstruction of poorly or non-textured scene areas. The codes, uniquely associated with visual primitives of the projected pattern, allow to solve the correspondence problem using local information only with robustness against pertubations like high curvatures, occlusions, out of field of view, out-of-focus. Real-time 3-D reconstruction is possible with pseudo-random arrays, where the encoding is done in a single pattern using spatial neighbourhood. Ensuring a higher Hamming distance between all the used codewords, will allow to correct more mislabeled primitives and thus ensure patterns globally more robust.(1) Up to now, the proposed coding schemes ensured the Hamming distance between all the primitives of the pattern which was generated offline, beforehand, producing Perfect SubMaps (PSM). But knowing the epipolar geometry of the projector-camera system, one can ensure the Hamming distance only between primitives that will project along nearby epipolar lines, because these only can produce correspondence ambiguity during the decoding process. As for such a new coding scheme, the Hamming distance have to be checked only in subsets of the pattern primitives, the patterns are globally far less constrained and therefore can be generated at a video framerate. We call such a new pattern coding as SubPerfect SubMaps (SPSM).