Efficient techniques for line drawing interpretation and their application to telephone company drawings
Juan F. Arias · 1996
Utility companies maintain the information of the layout of their service installations and equipment as large size (D-size or E-size) paper drawings. Managing and updating this paper based information is a costly and tedious process. There are commercially available CAD-based systems which allow management of this information in a more easy and efficient way, but the large number of drawings in every company makes the manual conversion of the paper drawings to these systems infeasible. Therefore, efficient interpretation systems must be developed to perform this task. Utility company drawings usually consist of graphical structures formed by intersecting horizontal and vertical line segments. In this research, techniques for the construction of interpretation systems for drawings with such characteristics have been developed. The methodology is based on the use of the spatial relation between the different types of intersections formed by orthogonal line segments to describe the graphical objects. With this purpose, efficient algorithms for the extraction of intersection features and detection of lines between pairs of intersections have been developed. Techniques for the efficient manipulation in memory of the large image files that result from scanning the paper drawings have also been developed. Using these techniques, interpretation systems for central office front equipment drawings and central office assignment table drawings from NYNEX, one of the local telephone companies in the U.S., have been constructed. An evaluation of the algorithms for the extraction of the intersection primitives and the detection of lines has been performed. The interpretation systems developed are also tested using real central office drawings provided by NYNEX.