Geomipmapping

Abstract: A body mounted camera support system for isolating the camera from body motion includes two arms linked together. Each of the arms is a four bar linkage with two tension cartridges each extending between two adjacent ones of the links. Two of the links are extended to form the body of the arm. These links are tubular in cross section and receive the tension cartridge. A single pin, in association with a yoke at one open end of the tubular link, locks the cartridge in place. Each tension cartridge includes a draw bar and a canister with a compression spring operatively positioned therebetween. The spring is adjusted to include shims which bias the bowing of the spring under initial compression load. A PTFE coating on the canister and on the coil spring further reduces friction.

Abstract: To solve the problem of low frame rate and high memory space cost in large scale terrain visualization, a real-time rendering algorithm based on linear quadtree is proposed in this paper. It consists of three parts. Firstly, digital elevation models (DEMs) are de-sampled to get the same size blocks, terrain pyramid model is built with different scales and biases factors offline. Then linear quadtree index of terrain blocks is created for fast query, a more reasonable scheduling scheme is defined, and every frame only allowed loading one terrain block in order to avoid unstable rendering quality. Finally, GPU-based morphing method is applied to slow down vertex popping; vertical skirt is used to eliminate crack. Compared with Geomipmapping algorithm, the experimental results show the proposed algorithm could drop down memory space, GPU processing time and GPU rendering batches significantly, and the rendering rate is high and smooth.

Abstract: To obtain dynamic real-time display of global topography data, based on the study of multiple LOD algorithms and synthesizing the advantages of three level-detailed algorithms, we propose an improved LOD algorithm based on extensible quadtree structure. Our algorithm adopts mipmapping method to simplify the grids, which keeps the efficiency of Ulrich and the simplicity of Geomipmapping. To eliminate the possible crack of different level-detailed blocks in splicing, we add skirt vertexed to the terrain blocks, so as to fully utilize the CPU batch in triangle processing and make optimization of the memory and speed. The experiments results show that the improved method can provide real-time and dynamic display of mass global topography data out of core. The combination with fractal algorithm has also increased the drawing resolution effectively.