A Visibility-Based Approach for Occupancy Grid Computation in Disparity Space

Occupancy grids are a very convenient tool for environment representation in robotics. This paper will detail a novel approach for computing occupancy grids from stereo vision and show its application to intelligent vehicles. In the proposed approach, occupancy is initially computed directly in the stereoscopic sensor's disparity space. The calculation formally accounts for the detection of obstacles and road pixels in disparity space, as well as partial occlusions in the scene. In the second stage, this disparity-space occupancy grid is transformed into a Cartesian space occupancy grid to be used by subsequent applications. This transformation includes spatial and temporal filtering. The proposed method is designed to easily be processed in parallel. Consequently, we chose to implement it on a graphics processing unit, which allows real-time processing for demanding applications. In this paper, we present this method, and we propose an application to the problem of perception in a road environment. Results are presented with real road data, qualitatively comparing this approach with other methods.