Estimating the Focus of Expansion in Analog VLSI

In the course of designing an integrated system for locating the focus of expansion (FOE) from a sequence of images taken while a camera is translating, a variety of direct motion vision algorithms based on image brightness gradients have been studied (McQuirk, 1991, 1996b). The location of the FOE is the intersection of the translation vector of the camera with the image plane, and hence gives the direction of camera motion. This paper describes two approaches that appeared promising for analog very large scale integrated (VLSI) circuit implementation. In particular, two algorithms based on these approaches are compared with respect to bias, robustness to noise, and suitability for realization in analog VLSI. From these results, one algorithm was chosen for implementation. This paper also briefly discuss the real-time analog CMOS/CCD VLSI architecture realized in the FOE chip.