A Review of Shadow Techniques in Augmented Reality

The seamless integration between computer-generated objects with real scene is desirable in augmented reality applications. The challenging task in augmented reality application is to make virtual objects mixed harmoniously with the real scene. To achieve these photorealistic rendering, it is not only considering visual complexity of virtual objects but the consistency of illumination between virtual objects with real scene must also be determined. With the consistency of illumination, virtual objects can cast shadows that appear as part of the real scene. The consistent shadow of the virtual objects will give a correct explanation of the relative distance between the virtual and the real objects. This paper explore regarding shadow techniques to improve photorealism for rendering virtual objects in augmented reality system. The evaluation among previous techniques presented in this paper is also important as a preliminary step for future findings related to the field of augmented reality.