Perfecting Vectorized Mechanical Drawings

摘要

This article describes a system which has been developed to convert scanned engineering drawings into a vectorized file. The vectorized file consists of lines, arcs, and circles and generates a description of paper-based engineering drawings. The scanned engineering drawing is initially vectorized by a system called RENDER using line-tracking and curve-fitting techniques. However, the results obtained after the initial vectorization are not adequate. This paper discusses a post-processing system called P-RENDER which has been developed to further refine the vectorized line drawings and to recreate the drawing with the exact numbers of lines and arcs. Dashed entities are also detected and recreated. For large C- or D-size engineering drawings the refinement algorithm also leads to a considerable reduction in the size of the CAD database.