Image based rendering with stable frame rates

This paper presents an efficient keyframeless image-based rendering technique. An intermediate image is used to exploit the coherences among neighboring frames. The pixels in the intermediate image are first rendered by a ray-casting method and then warped to the intermediate image at the current viewpoint and view direction. We use an offset buffer to record the precise positions of these pixels in the intermediate image. Every frame is generated in three steps: warping the intermediate image onto the frame, filling in holes, and selectively rendering a group of "old" pixels. By dynamically adjusting the number of those "old" pixels in the last step, the workload at every frame can be balanced. The pixels generated by the last two steps make contributions to the new intermediate image. Unlike occasional keyframes in conventional image-based rendering which need to be totally rerendered, intermediate images only need to be partially updated at every frame. In this way, we guarantee more stable frame rates and more uniform image qualities. The intermediate image can be warped efficiently by a modified incremental 3D warp algorithm. As a specific application, we demonstrate our technique with a voxel-based terrain rendering system.