Surface orientation imager using three-phase amplitude-modulated illumination and correlation image sensor

We propose a novel system for real-time three-dimensional surface orientation measurement. The advantages of our method are: (1) single frame capture of normal vector distribution, (2) dense, pixel-wise capture of normal vectors, and (3) independence on surface reflectance and background illumination. This system consists of two components; one is the sinusoidally amplitude-modulated three-phase (3P) light sources at vertices of a triangle and another is the three-phase correlation image sensor (3PCIS) for demodulating the amplitude and phase of reflected light from the surface. Based on the photometric stereo principle, the phase and amplitude can be easily converted to the azimuth and inclination, respectively, of the normal vector of the surface. We implemented this system using our CMOS 64 × 64 pixel 3PCIS developed by us and successfully reconstructed the normal vector map in its frame rate (30Hz).