Invariant features for dice recognition across illumination

A system is proposed for the recognition of the dot numbers on dice in general table game settings. Different from previous dice recognition systems which use a single top-view camera and work only under controlled illumination, the proposed one uses multiple cameras and works for uncontrolled illumination. The proposed system exploits the local invariant features robust to illumination variation and good for building the homographies between multiple viewpoints. The homographies can enhance coplanar features and weaken non-coplanar features, giving a way to segment the top surfaces of the dice. A coarse-to-fine search with a shape-dependent local descriptor is designed to identify the dots on the segmented top surfaces and recognize their spatial distribution patterns. Experiments show that the proposed system can achieve a superb recognition rate for various uncontrolled illumination conditions.