Point Photoclinometry


Think of the scene as made up of flat panels the
size of pixels in the image.

Given photometric information for the image,
find the slope of a surface that could yield the
measured brightness in a pixel.

Assumptions:
No overall tilt to the terrain in the image
Shading in the image is due to topography,
        not albedo variations

The resulting slopes are in the down-sun direction.