实时栅格化的全球矢量数据可视化及交互操作

Visualization and interactive operation of global-scale vector on the basis of real-time rasterization

通过采用视点相关的数据动态调用策略,实现了视景体内矢量线、面对象的动态查询和检索;利用Bresenham算法和填充法分别对线、面对象进行实时栅格化,生成矢量纹理数据,并将矢量纹理数据映射到地形格网表面,实现了矢量数据快速可视化;利用点选操作获取拾取点的屏幕坐标,通过坐标变换计算出拾取点的空间坐标,依据拾取点的空间坐标实现矢量查询、选择等交互操作.应用我国省区边界数据和美国地质调查局的GOTOPO30数据进行了相关实验.结果表明:实时栅格化的矢量可视化表达方法每秒渲染帧数在40帧左右,渲染效率远高于几何法;而且避免纹理走样现象的产生.

Dynamic query and search of vector polyline and polygon objects in view frustum was realized with the help of view-dependent data loading technology. Using Bresenham＇ algorithm and filling algorithm carried out the real-time rasterization on polyline and polygon objects, and produced the vector texture data, at the same time the vector texture data were mapped onto terrain surface to realize the quickly visualization of vector data. The interactive operations, such as vector query, selecting operation and so forth, were realized according to spatial coordi- nates indicated by picking point. The experiment to test the feasibility of those algorithms is done by using vector data in China and American USGS GOTOPO30 DEM data. The results show that： the average speed of representing vector of this method is nearly 40 frames per sec- ond in the use of vector visualization expression, and the rendering efficiency is better than that of geometry-based method, while heavy texture deformity is avoided completely.