Maps are of various sizes, scales, resolutions, saturation, and intensity ranges.
They also contain diverse topographic elements and cartographic techniques. The JPL approach to Map Separates is based on the back-propagation techniques. The CRI approach to map understanding is based on the expert systems techniques. The resulting techniques are comparable in quality and give higher performance than the backpropagation-based approach. In the following, we discuss in more detail various algorithms involved in this problem, with the focus on the RGB clustering techniques.