The SAD value for each pixel is normalized by the SAD value that would be found if the right image was matched against a blank image. If the normalized value is below a threshold, this location is marked as invalid in the depth map. Further pixel noise is removed from the depth map by marking invalid all pixels that don't have the same depth value as the pixel above and below them.
Shiny linoleum floor tends to reflect objects and the stereo detects these reflections as being under the floor. Each pixel below the horizon is looked at and pixel that are on or below the floor are marked invalid to ignore floor texture and floor reflections. The location of the floor relative to the cameras is known from the calibration stage.
Once all the invalid pixels in the image have been found, a planar map is formed by taking the closest disparity in each column of the depth map. This forms a 1 by 128 planar map that represents the nearest obstacle in each of the directions that the cameras can see. The planar map generated from the depth map in Figure 5 is shown in Figure 6.
