Structured light with coded aperture for wide range 3D measurement

In this paper, we propose an active 3D measurement method using structured light system, which can measure wide range of depth. General structured light system requires correspondence between projection patterns and camera observed patterns. Hence, both the projected pattern and the camera image should be in focus on the target. This condition makes a severe limitation on depth range of 3D measurement. Our technique resolves the range limitation by using coded aperture (CA) on projector. It can be understood as a structured light system using Depth from Defocus (DfD) technique, in which defocus of projected light pattern is utilized. By allowing blurry pattern of projection, the measurement range is extended compared to common structured light system. Moreover, CA efficiently improves its accuracy.