Beyond the interference problem: hierarchical patterns for multiple-projector structured light system.

Three-dimensional reconstruction of a dynamic object based on the structured light (SL) technique has attracted intensive research. Since a single projector only covers a limited area of the scene, multiple projectors should be employed simultaneously to extend the imaging area for a 3D object. However, patterns projected by different projectors superpose each other in a light-intersected area, which makes it difficult to recognize the original patterns and obtain the correct depth maps. To solve such a problem, we propose a method to design hierarchical patterns that can be separated from each other. In the proposed patterns, each pixel in binary patterns based on the de Bruijn sequence is replaced by a different bin with limited size. Then the proposed patterns can be separated by identifying distributions of colors in each bin in superposed patterns, and depth maps are obtained by decoding the separated patterns. To verify the performance of the proposed method, we design two hierarchical patterns and conduct several experiments in different scenes. Experimental results demonstrate that the proposed patterns can be separated in a multiple-projector SL system to obtain accurate depth maps, and they are robust for different conditions.