Three-dimensional sensing system with point light sources

This paper describes a new 3D sensing method for getting geometrical parameters of planar surfaces and cylindrical objects in a scene. The sensor system consists of two or three TV cameras with point light sources being placed at the projection centers of the cameras. The light sources are switched on alternately, and images under each lighting are recorded with the cameras. Under a point light source, even on a planar surface, there is a distribution of luminance due to diffuse and specular reflections. Since the light is emitted from the projection center, the positions of the peak of the luminance distribution on each surface directly provide such geometrical information on the surface. Our approach is based on measuring the peak positions on the images. This method speeds up considerably the acquisition of geometrical information on an entire scene, because the geometrical information on target objects can be obtained without analyzing range maps. The equipment setup for emitting light from the projection center is very simple and the illuminators can be easily set up at ordinary TV cameras. The proposed technique would be useful for real-world robotic applications such as navigation of indoor mobile robots. The experimental results show that the method is adequate for such purposes.