基于拓扑映射的视图轮廓信息自动获取算法

为克服轮廓信息提取中现有方法计算量大和角度判别复杂等问题，提出了基于拓扑映射的视图轮廓信息求取方法。该方法是基于拓扑映射原理，首先将各候选路径上的点变换为射影直线上的映射点，然后利用映射点与候选路径走向排序的拓扑不变性来进行路径判别，这样将路径分支处的下一路径走向判别转化为映射点在射影直线上的走向判别。若射影直线为水平，则映射点的求取非常简单、方便。该方法由于避免了复杂的角度计算，因而计算效率显著提高，其对工程图视图的自动划分、装配图处理及尺寸布置等有着重要的作用。

The Algorithm of Automatic Acquisition of View Outline Information Based on Topological Mapping

To solve the problem of acquiring the information of view outline, some experts have proposed many methods. But there are too much calculation and too complex determinant in prevail methods, which has become an important problem. Based on topological mapping, this paper puts forward automatically acquiring the information of view outline. At first, based on topological mapping principle, the method maps points of the candidate path onto the projection line. And then, using the topological sequence compatibility of points on the projection line and the candidate path, the problem of determining the trend of the next branch is converted to decision of the trend of projection lines. Finally, according to the sort order of mapping points, the path can be determined. Since the projection line is horizontal, it is easy and convenient to obtain the mapping points. This algorithm also saliently improves the computation efficiency by refraining from the complex angular calculations. Moreover, the algorithm will play an important role in automatic partitioning of engineering drawings, assembly diagram processing and dimension arrangement.