Development of a video-rate range finder using dynamic threshold method for characteristic point detection

This study develops a video-rate stereo range finding circuit to obtain the depth to objects in a scene by processing video signals (R, G, B, and brightness signals) from binocular CCD cameras. The electronic circuit implements a dynamic threshold method to decrease the affection of signal noises in characteristic points detection, where a video signal from each CCD camera is compared with multiple thresholds shifting dynamically by feeding back the previous comparison result. Several object depth measurement experiments for simple indoor scenes show that the dynamic threshold method gives high acquisition and correct rates of depth data compared with those by a fixed threshold method for the video signals and a relative method for R, G, and B signals utilized in the authors' previous range finders.