A video-rate range sensor based on depth from defocus

Recovering the depth information derived from dynamic scenes implies real-time range estimation. This paper addresses the implementation of a bifocal range sensor which estimates the depth by measuring the relative blurring between two images captured with different focal settings. To recover the depth accurately even in cases when the scene is textureless, one possible solution is to project a structured light on the scene. As a consequence, in the scene's spectrum a spatial frequency derived from illumination pattern is evident. The resulting algorithm involves only simple local operations, this assures the possibility of computing the depth at a rate of 10 frames per second. The experimental results indicate that the accuracy of this proposed sensor compares well with that offered by other methods such as stereo and motion parallax, while avoiding the problems caused by occlusion and missing parts. (C) 2001 Elsevier Science Ltd. All rights reserved.