A simplified normal optical flow measurement CMOS camera

Various motion properties of an image can be computed by using normal flow measurements. Notable among these are focus of expansion, time to contact. Many VLSI systems that combine focal plane processing with imaging have been proposed. However, these systems mostly suffer due to lower spatial resolution. This paper presents a two-dimensional dense simplified normal optical flow measurement chip implemented in 0.5-mum CMOS process that combines imaging and processing on the same chip efficiently. The algorithm outputs the image, computes partial derivatives with respect to time and space, and uses their ratio to compute a simplified version of the normal flow velocity. The chip is composed of an array of 92times52 of APS pixels, occupies an area of 4.5 mm² and consumes 2.6 mW power. This paper illustrates the operation of the chip by first presenting results from individual blocks and then from system-level testing. Furthermore, we demonstrate the feasibility of scaling the chip to higher resolutions without affecting the processing