基于知识推理的尺寸单元识别与重构

On Recognition and Reconstruction of Dimension Sets by Knowledge Inference

尺寸单元的识别与重构是工程图理解的重要环节。提出一种策略:着眼于尺寸单元的拓扑结构,从尺寸约束语义入手,分别进行尺寸数字与尺寸线匹配、尺寸线与尺寸界线匹配,再经匹配测试来确认尺寸单元,最后推理确定箭头的方位和几何属性,实现尺寸单元的拓扑重构。实验显示该算法具有适应性好、识别率高的特点。

Dimension set recognition and reconstruction plays a key role in vectorization of engineering drawing. In this paper, we present an algorithm to recognize and reconstruct dimension sets. First, based on knowledge of engineering drawing, the textboxes are matched with the shapes and the witnesses are matched with the shapes for building the topological characteristic of dimension sets. Then, the sort-orientation-direction triplets coding of an arrow is formed. Finally, the dimension sets are reconstructed according to these triplets coding. The algorithm is proved to be of powerful adaptability and high recognition.