Converting CAD Drawings to Product Models

Sammanfattning: The fundamental aim of this study is to examine whether itis possible to automatically convert vector-based drawings toproduct models. The reason fordoing this is that the newobject-based systems cannot make use of the information storedin CAD drawings, which limits the usability of thesesystems.Converting paper drawings to vector-format is used today andprovides recognition of lines and text, but does not interpretwhat the shapes represent. A language for describing thegeometrical representations that could be processed directlyinto a recognition program for building elements is missing. Itis easier to describe how to recognize a line as a series ofdots in a raster image, than it is to describe how a complexsymbol of a building element looks like.The approach in this research work has been to testdifferent shape recognition algorithms. The proposed method canbe divided into four processes: grouping of geometricalprimitives, classifying these groups, interpreting the contentand analyzing the relationships between the groups. Thealgorithms developed here are based on research within relateddomains, such as pattern recognition and artificialintelligence.The algorithms have been developed in a prototypeimplementation and were tested with three layer-structureddrawings used in practice. The results of the tests show thatthere are no crucial obstacles to recognizing a large part ofthe symbols of building elements in a CAD drawing. Therequirement is that the recognition system is able todifferentiate one from another and be tolerant of errors andvariations in the shapes.Keywords:Shape recognition, shape interpretation,product models