Multi-level Block Information Extraction in Engineering Drawings Based on Depth-first Algorithm

The problem of multi-level block reference is analyzed for the process of information extraction in engineering drawings. And the relationship of reference blocks has been established. By using depth-first algorithm, the multi-level reference path of blocks and the parameter transformation can be searched. Based on the algorithm, an arithmetic flow is proposed. And the method of coordinate transformation of reference blocks is expounded. The new method has important significance for comprehensiveness and accuracy of information automatic extraction of engineering drawings which contains multi-level reference blocks.