Can we Invert a Local Reflectance Model From a Single Specular Highlight with Known Scene Geometry and Camera Pose?

Recovering the scene’s illumination from images is a crucial step in Augmented and Diminished Reality. We present an experimental investigation to assess the well-posedness of this problem (i) using a known scene geometry and camera pose and (ii) assuming that a local reflectance model such as Blinn-Phong’s holds. Based on results on synthetic and real data, we establish two major observations. First, the problem of retrieving the full local reflectance model’s parameters and light source position from the original image is ill-posed. Second, the specular parameters including the light source position can be stably estimated from the image’s specular component using a single specular highlight region.