Reflected-Scene Impostors for Realistic Reflections at Interactive Rates

We present a technique for rendering reflections on complex reflectors at interactive rates based on approximating the geometry of the reflected scene with impostors. The reflections correctly convey the distance to the reflector surface and provide motion parallax. Two types of impostors are adapted to the reflections framework: billboards and depth maps. Billboards remove most of the problems of environment mapped reflections at only a small additional cost. Second order reflections are supported by introducing reflective billboards. Higher quality reflections that provide motion parallax within a reflected object are obtained by approximating the reflective geometry with depth maps. The computation of the intersection between a reflected ray and a depth map is accelerated by leveraging epipolar constraints. Like environment mapping, our technique does not pose any restriction on the geometry of the reflector, supports dynamic scenes, and runs at interactive rates with the help of graphics hardware.