用于DCS的任意多边形截幅方法

在DCS中,对绘图数据不仅需要有矩形截幅功能,而且还常常碰到需要进行任意多边形截幅的情况。本文引入了广义多边形截幅窗口的概念,提出了一种以方位角判别点与多边形关系的方法;为了提高截幅运算的速度,给出了适用于DCS的自动生成截幅窗口的原理和方法,最后还讨论了对圆形符号进行截幅处理的问题。使用本文提出的任意多边形截幅方法不仅使DCS的图形处理功能更加完善,而且可改进采样方法,避免了地籍图上跨越界址线的地物符号可能出现的不合理现象。

AN ARBITARY POLYGON CLIPPING METHOD FOR DCS

In DCS, both rectangle clipping and arbitary polygon clipping functions are needed. This paper introduces the concept of wide-meaning polygon clipping window, develops an method to judge the relationships of a point and a polygon with bearing angles, gives the theory and method of automatically forming the clipping window for DCS to speed up clipping calculation, and finally, discusses he clipping method for circles. By using the clipping method developed in this paper, the function of raph processing in DCS can be enhanced and the sampling procedure can be improved so as to avoid the unreasonable phenomena, which possibly exist when an object crosses the boundary line in cadastre maps.