| The main subject is study for volume rendering of 3D-reconstruction, volume rendering is a theory, measure, technique, which convert data got from science calculation to image or graphics using computer graphics processing technology, and show the image or graphics in screen. It covers almost all the field related with computer, such as medical science, biology, aerospace industry, industry nondestructive inspection, archaeology, meteorolo-gical phenomena and geologic prospecting. Study on volume rendering has important significance on science and worthiness in practical application.The main algorithm for volume rendering is introduced, which describes process of the ray-tracing algorithm ,as the algorithm is nimble and details of image is rich, but the data amount is ample, and the calculation is complicated , so it is necessary to accelerate the volume rendering algorithm.A new acceleration technique for ray casting volume rendering called region leaping, is advanced. it is based on factorization of equation which homogeneity gray element inside a volume be sampled and composed in theory. We create an region leaping data structure to help identifying homogeneous voxel cubes, which is independent of the viewing parameters and shading conditions. Accumulated colors and transparencies of homogeneous ray segments are pre-computed into a look-up table according to different voxelvalues and ray segment lengths.Also, an algorithm for volume rendering in an environment of parallel virtual machine is improved, in order to reduce the communication cost, as well as to guarantee the locality of all subtasks, the volume data are divided and organized as a series of slices. By maintaining and employing a database of the performance index, the task subdivision algorithm produces an acceptable load balancing. An asynchronous binary method is introduced, which can reduce time for combination of partial images.Finally, the algorithms proposed in the paper are validated through extensive experiments. |
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