On computing a `fuzzy´ focus of expansion for autonomous navigation

The focus of expansion (FOE) is an important concept in dynamic scene analysis, particularly where translational motion is dominant, as in mobile robot applications. In practice, it is difficult to determine the exact location of the FOE from a given set of displacement vectors due to the effects of camera rotation, digitization, and noise. Instead of a single image location, the authors propose to compute a connected region, termed fuzzy FOE, that marks the approximate direction of camera heading. The fuzzy FOE provides numerous clues about 3D scene structure and independent object motion. The main problems of the classic FOE approach are discussed, concentrating on the details of computing the fuzzy FOE for a camera undergoing translation and rotation in 3D space. Results on real outdoor images are presented. Experiments show that even erroneous point matches in the given image displacement vector field can be tolerated, which is a necessity in a fully automated process