Symmetry based semantic analysis of engineering drawings

Engineering drawings have posed significant challenges to image analysis for many decades. The goal is to take images of scanned engineering drawings and interpret them so as to understand their contents (e.g., characters, digits, line segments, box segments etc.). This is known as semantic analysis. We propose a new approach here which takes advantage of the man-made nature of drawings: there is a tremendous amount of symmetry. We exploit this insight to enhance our previously reported system, the Non-Deterministic Agent System (NDAS), with symmetry-based analysis tools. Agents work independently but use each others results to produce the final result (e.g., form segmentation, character analysis, structural analysis, boundary segmentation, etc.). We use the wreath product representation both to characterize symmetry as well as to structure a Bayesian network model of the uncertainty. This approach permits wide application to perform semantic analysis of engineering drawings.