Abstract

Active vision techniques use programmable light sources, such as pro jectors, whose intensities can be controlled over space and time. We present a broad framework for fast active vision using Dig- ital Light Processing (DLP) pro jectors. The digital micromirror array (DMD) in a DLP pro jector is capable of switching mirrors “on” and “off ” at high speeds (106 /s). An off-the-shelf DLP pro jector, however, effectively operates at much lower rates (30-60Hz) by emitting smaller intensities that are integrated over time by a sensor (eye or camera) to produce the desired brightness value. Our key idea is to exploit this “temporal dithering” of illumination, as observed by a high-speed cam- era. The dithering encodes each brightness value uniquely and may be used in conjunction with virtually any active vision technique. We ap- ply our approach to five well-known problems: (a) structured light-based range finding, (b) photometric stereo, (c) illumination de-multiplexing, (d) high frequency preserving motion-blur and (e) separation of direct and global scene components, achieving significant speedups in perfor- mance. In all our methods, the pro jector receives a single image as input whereas the camera acquires a sequence of frames.