Fig. 2
From: Low-power depth-based descending stair detection for smart assistive devices
Rectification of the depth values: The scenes in (a) represent the left captures of the stereo camera. The Konolige’s algorithm allows the extraction of the raw depth map (b) where each pixel value is the raw distance between its corresponding 3D point and the sensor plane. Each pixel value of (b) is rectified according to the angle of the vision system on the rollator with respect to the floor. For a flat ground as depicted in the first row, the final depth map (c) is uniform