The disparity map is checked for occluded pixels. This is usually called ‘left-right consistency check’. A pixel is only accepted if it is a mutually best match with the assigned right image pixel. Due to subpixel interpolation and half-occluded pixels, it is reasonable to allow small deviations from ‘exact mutual’ matches. This threshold sets the allowed range of mismatch in pixels.
An integer specifying the threshold in disparities by which a pixel might be occluded by another pixel to still be accepted as valid. Negative values disable the occlusion detection and will leave wrongly associated regions in occluded image areas.
Setting a negative value (e.g. -1) for this parameter will disable filtering of shadowed areas. This will leave arbitrary depth values in shadowed areas.
The image below shows a few associations between two corresponding rows of the left and right image. Black areas are occluded and do not have a corresponding pixel in the other image.