The Importance of Shadows in Augmented Reality

In Augmented Reality (AR) virtual objects are visually added to real scenary, i.e., the real scene is augmented with virtual objects. In some AR applications it is a goal in itself that the virtual objects are indistinguishable from real objects. A major difficulty in achieving this realism is to ensure that the virtual objects are rendered using lighting conditions which are consistent with the lighting conditions in the real scene. If this difficulty can be overcome the virtual objects can be shaded, and can cast shadows, just as if they had actually been part of the real scene. Our work focuses on developing methods for determining such lighting conditions and results show that adding the correct shading and shadowing to virtual objects substantially enhances the visual quality of the augmented scene, and makes it much easier for people to perceive the spatial relations between real and virtual objects.