嵌入式GIS中矢量地图快速显示方法研究

Study method of fast displaying vector map in embedded GIS

为提高嵌入式GIS中矢量地图的显示速度,建立了要素分级的多层网格索引模型。该模型算法简单,耗用内存小,便于实现。显示地图时,直接依据当前的显示比例,读取对应网格索引中相应级别的地图数据,避免了大量非屏幕区域的冗余地图数据读取,极大地提高了显示速度,同时设计了折线与矩形求交的算法来提高地图数据显示处理的效率。实验结果表明,该方法能显著提高嵌入式平台矢量地图的显示速度,并且已成功应用于手持GPS定位终端软件。

To speed the display of vector map in embedded GIS domain,a model of multi-level grid index with geo-entity graded according the importance of displaying is built. The model is simple and effective,costs small memory and is easy to be realized. When to display map,immediately according current display ratio,read geo-entities of the corresponding grade in the accordant grid index,so avoid reading large numbers of redundant geo-entities out of screen,in the result largely speeds up the display of vector map. The algorithm of the intersecting of a poly-line and a rect also is introduced to improve the efficiency of the display process of map data. The test results show that the methods introduced can obviously speed up the display of vector map with large data. The methods introduced are successfully used in the GPS-navigation software of PDA.