Three-Dimensional Volume Data Generation And Three-Dimensional Buffer Analysis

In the research of the three-dimensional Geographic Information System (GIS), three-dimensional data model and data structure is the core. The three-dimensional spatial data model includes the surface model and the volume model according to the data description format. Because of spatial objects can be rendered by the discrete voxel values, volume model has more advantages in showing inner characters of spatial object. It has higher efficiency in some spatial analysis. So it is one of important basis for spatial information system. The algorithm of three-dimensional volume data generation and the algorithm of three-dimensional buffer analysis for volume data model are mostly researched in this thesis.In the aspect of three-dimensional volume data generation, a rapid solid voxelization algorithm based on triangular mesh model is propoes in this thesis. The algorithm can be realized in two steps:the first step is surface voxelization, dividing the triangular faces of triangular mesh model into some other new minor triangle chip which is sufficiently small, then voxelizing these triangle vertexes, which can convert surface voxelization to points voxelization; the second step is internal voxelization, the internal voxel can be recognized by using the six directional projection of the voxel model which can be obtained by extending the Z-buffer algorithm, the number of voxel which needs recognizing can be reduced by combining with the edge marking fill algorithm. As for complicated and fine triangular mesh model, the algorithm not only can efficiently generate voxel model of 26-connected which is approached to original model, but also have high time efficiency.In the aspect of three-dimensional buffer analysis, the algorithm of three dimensional signed euclidean distance transform is used, but the data quantity in high resolution is large, and even may larger than loading capacity of memory, it leads the general algorithm cannot be used. Therefore, a massive data processing strategy of three-dimensional buffer is given in this thesis based on the partition strategy. The results of experiment show that the method can effectively complete the three-dimensional buffer analysis under the massive data.