| Augmented reality (AR) is concerned with the enhancement of visual information about a real scene through the embedding of one or more computer graphics objects, or 3D virtual objects (VOs). Already used successfully in applications such as telerobotics, medicine, manufacturing, aviation, and entertainment, AR can be thought of as an intermediary point on the spectrum from real-time video (completely real) to virtual reality (completely synthetic). On this theme, the present work addresses the “interposition” problem, that is, physical interactions between real and virtual objects that must be consistent with the natural opacity and rigidity constraints. A VO must occlude (or be occluded by) real objects situated behind (or in front of) it with respect to the observer. Moreover, a VO should not penetrate other objects when this is not expressly allowed. Essentially, one can distinguish four valid types of interposition, or embedding, of a VO in a real scene: (1) Overlay, when a VO is effectively in front of the real scene; (2) Occlusion, when a VO passes behind or is inside a real object; (3) Collision, when a VO is in contact with a real object; (4) Compliance, when a VO moves on or in contact with a real surface. (Abstract shortened by UMI.)... |
