1. A method performed by a process executing on a computer system, the method comprising: identifying an object of interest in a digital image; projecting at least a portion of the digital image corresponding to the object of interest onto a three dimensional (3D) model that includes a polygon-mesh corresponding to the object's shape; and determining one or more properties of a light source that illuminated the object in the digital image at an instant that the image was captured based at least in part on a characteristic of one or more polygons in the 3D model onto which the digital image portion was projected.