A real-time 3D IR camera based on hierarchical orthogonal coding

We present a real-time 3D camera based on IR (infrared) structured light suitable for robots working in home environment. First, we implemented a HOC (hierarchical orthogonal coding) based FPGA board. The HOC gives robust depth images because the signal separation coding provides not only the separation of overlapped codes, but also a robust decision on pixel correspondence with error correction. The FPGA module can handle high computational cost of HOC based signal separation coding. Second, we implemented a compact optic system of the camera to project and receive IR structured light. The invisible IR pattern light provides users inconvenient in the home environment. Various objects and workspaces which has continuous and/or non-continuous surface are tested and, sensitivity to illumination change and processing time are analyzed. The experiment results show the robust performance for surface smoothness, color, and materials of objects used in home environment. The proposed approach opens a greater feasibility of applying structured light based depth imaging to a 3D modeling of cluttered workspace for home service robots