Rendering - Image-Based Rendering

Post-Rendering Warp

A particularly exciting application of image-based rendering is post-rendering warp [MARK97], which promises a cheap but effective 5X - 10X speedup for renderers originally generating only a few frames per second. The fundamental idea is to take the combination of image and z-buffer from the renderer and warp it to nearby user positions while waiting for the next image from the renderer. The current solution to the most serious problem of such image warping, namely gaps caused by newly unoccluded regions for which there is no information, is to use two range images rather than one, each warped to the current user location, and then merge them. To avoid doubling the burden on the original renderer, the two range images used are the last two generated by the renderer, and to avoid the problem of these having been generated for places far away from the user's current location, the renderer is asked to generate an image not for the current location, but for the location where the user is predicted to be at the next renderer's frame time. The results from the current software (non-real time) implementation of post-rendering warp are so startling that viewers typically have a hard time detecting the difference between post-rendering and standard per-frame rendering. It appears feasible to implement post-rendering warp on a single chip, allowing such dramatic performance gains at a very modest cost.