| Overview |
| The sample-based camera (SBC) is a method for rendering curved reflectors based on projecting reflected vertices. The SBC is a set of BSP trees with simple cameras at their leafs. When the reflector geometry is complex, the viewing volumes of the simple cameras intersect and they cannot be efficiently separated by the BSP tree, which leads to inefficient projection. In order to support complex reflectors we developed a reflection rendering technique based on simplifying the reflected scene, which is approximated with billboard and depth map impostors. The intersection between a ray and a billboard is inexpensive. For depth maps we developed an intersection algorithm that leverages epipolar constraints to efficiently compute a quality approximation for the first intersection with a ray. Like environment mapping, our technique does not pose any restriction on the geometry of the reflectors, it supports dynamic scenes, and it runs at interactive rates with the help of graphics hardware. Unlike environment mapping, reflected-scene impostors produce realistic reflections by correctly conveying the distance to the reflector surface and by providing motion parallax. |
 
Four inter-reflecting teapots, 40fps (left) and reflection attenuation with distance and Fresnel effects, 66fps (right). Both images were rendered with billboard impostors. |
 
Intersecting diffuse and reflective bunnies, 16fps. The image was rendered with a depth map impostor. |
 
Reflectors distorted in real time. The images were rendered with a billboard at refresh rate (left) and a depth map impostor at 16fps (right). |
 
Extreme distortions caused by concave reflectors. Billboard (left) and depth image (right) impostors handle extreme minification and magnification well. |
 
Illustration of morph from billboard to environment mapping. The statues surrounding the teapot (left) are part of the environment map. The billboard is highlighted with purple. The reflection is continuous between the billboard and the environment map (right). |
