1. A method for obtaining a tree-dimensional representation of a light source distribution located inside a mammal, the method comprising: obtaining a topographical surface representation of the mammal; providing surface light image data from light emitted from a surface of the mammal originating from the light source distribution located inside the mammal; and using a processing system, reconstructing a three-dimensional representation of the light source distribution internal to the mammal using the topographical surface representation and the surface light emission data.