Robust Estimation of Light Directions and Diffuse Reflectance of Known Shape Object

We propose a method to determine the light direction and diffuse reflectance property from two images with different light conditions. In our method, it is assumed that the shape of the target object is given. Using the relationships between light direction and diffuse reflectance, we can estimate both of them simultaneously from more than five points on two images. While speculars and shadows affect the estimation as outlier and cause errors, we can avoid these outliers by robust estimation using Random Sample Consensus (RANSAC). The good nature of our method in terms of feasibility and stability is shown in experimental results with both simulation and real images.