TASC's Dr. Mark Carlotto developed an algorithm that enables one to extract approximate elevation relief from imagery. It's a "shape from shading" algorithm. The Martian imagery provided an excellent dataset for prototyping this algorithm as with no atmosphere and well understood reflectivity, the surface provides near perfect Lambertian reflection - and hence a means of determining relative surface normals. He developed this algorithm under the same period as some scientists were reviewing remotly sensed imagery of the Martian surface. They discovered the so called "Face on Mars", a geological feature on the surface which looks like a human face.