Marker cube and probe sphere based illuminant detection algorithm

In order to integrate seamlessly a virtual object in a real scene in augmented reality (AR) system, we need to simulate the interactions of the virtual object with the illumination of the scene. Acquiring the knowledge of illuminant direction is crucial in this work. We present a novel approach for estimating the direction from a single image of a scene that is illuminated by a light source regardless it is point light source or directional one. We propose to employ a marker cube, which is used to register to determine the rigid transformation relating 2D images to known 3D geometry, and a Lambertian probe sphere, which is used to estimate the light source direction by image processing. The key process is finding and extracting the intensity occluding curve on the sphere. Experimental results show that our approach is computationally efficient and the light source direction can be accurately obtained by it.