一种栅格化矢量地图的拾取交互方法

A Picking Interaction Method of Rasterized Vector Map

针对纹理法渲染的栅格化矢量地图难以直接进行交互的问题,设计了一种栅格化矢量地图的拾取交互方法。基于实际面型矢量顶点数目多、多边形分离、空洞多边形等特性,改进了传统的射线求交判断点是否在多边形内的算法,使其可适用于实际面型矢量拾取;同时,提出了一种基于半平面连续链的新型内角和算法,可大幅降低传统内角和算法的计算量,实现了栅格化矢量地图的拾取交互。应用不同复杂程度的矢量数据进行相关实验,结果表明,在明显提高矢量渲染效率的同时,避免了在三维场景下矢量渲染不贴地的情况下,可以实现矢量兴趣要素拾取,且所提矢量拾取方法实时性良好,拾取响应时间只取决于矢量数据本身复杂度,与三维地形复杂度无关,可以满足GIS的需求。

Aiming at the problem that the vector map rendered based on texture is difficult to realize the interaction, an interactive method of the rasterized vector map is designed. Based on the characteristic of polygonal vector which has a great quantity of vertices, separate polygon and hole）, polygon,the traditional ray intersection method determining whether a point is in a polygon is improved to apply to polygonal vector. Meanwhile, an interior angle summation based on half-plane continuous chain which could reduce the computation of the traditional interior algorithm is proposed. The experiment is done by using vector data with different degrees of complexity. The result shows that the efficiency of rendering based on rasterization is significantly increased and the bad overlaying performance of vector rendering in 3D scene is improved. Vector map interaction could be realized in this case. The proposed interaction method which is only according to the degrees of complexity of vector data and has nothing to do with the degrees of complexity of terrain, guarantees favorable performance of real-time to meet the need of GIS.