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借鉴计算几何学的理论方法,提出一种基于多边形梯形剖分思想的实现方法。首先利用扫描线技术将多边形分解为梯形面片集,以便将多边形的布尔运算转化为梯形面片间的布尔运算;这些梯形面片以扫描行为单元进行组织,梯形之间的布尔运算被限定在相同的扫描行内,可有效简化核心计算过程;在完成梯形单元布尔运算并得到结果梯形集后,通过边界追踪完成多边形重构。该方法可规避多数矢量算法中多边形各边之间复杂的空间关系判断,实现过程相对简单,具有较高的计算效率且易于理解。同时,借助简单的多属性条件提取,可实现GIS中的Union、Erase、Clip、Intersect等多种类型的空间操作,具有拓展性。 更多还原

【Abstract】 A new algorithm for Boolean operations is presented,which incorporates trapezoidal decomposition.The involved polygons are decomposed into two sets of trapezoids by the sweep-line,therefore Boolean operations on polygons are transformed into the Boolean operations on the decomposed trapezoids.Since these trapezoids are organized and stored by row,thus the Boolean operations between them are confined within one row;in consequence,the computation efficiency could be improved.Once the resulting set... 更多还原