Automatic generation of consistent shadows for augmented reality

In the context of mixed reality, it is difficult to simulate shadow interaction between real and virtual objects when only an approximate geometry of the real scene and the light source is known. In this paper, we present a realtime rendering solution to simulate colour-consistent virtual shadows in a real scene. The rendering consists of a three-step mechanism: shadow detection, shadow protection and shadow generation. In the shadow detection step, the shadows due to real objects are automatically identified using the texture information and an initial estimate of the shadow region. In the next step, a protection mask is created to prevent further rendering in those shadow regions. Finally, the virtual shadows are generated using shadow volumes and a pre-defined scaling factor that adapts the intensity of the virtual shadows to the real shadow. The procedure detects and generates shadows in real time, consistent with those already present in the scene and offers an automatic and real-time solution for common illumination, suitable for augmented reality.