Lifting wavelet-based progressive compression and real-time rendering to large terrain

To alleviate the burden for massive-data storage, transmission and rendering in real-time large terrain visualization systems, based on lifting wavelet, an algorithm is proposed for integrating terrain dataset progressive compression and real-time aggregated LOD rendering. By the algorithm, the lifting wavelet transform model for terrain chunk is built to map the chunk simplification and refinement to corresponding wavelet transforms. Then the chunk-quadtree is constructed using the chunk-based wavelet transform model. The wavelet coefficients generated during the hierarchy construction are progressively compressed by an indirect look-up table technique. Based on the chunk-hierarchy compressed, the active chunks for a viewport are decided, then the datasets needed are incrementally loaded and uncompressed, with the adaptive terrain mesh produced at the same time, to perform terrain rendering. During rendering, real-time chunk uncompress and wavelet transforms are processed on GPU. Test results show that the algorithm can be used to compress datasets efficiently and its real-time uncompress efficiency and rendering performance are both excellent.