WIZ — A prototype for knowledge-based drawing interpretation
The WIZ-system is a prototype for interpretation of technical drawings. The paper introduces drawing interpretation as a knowledge processing task. Starting from a discussion about the necessary kinds of knowledge we present our frame-based knowledge structure and explain its implementation using a generic blackboard model, having easy adaptibility to new application domains in mind. The main part of the paper deals with the basic interpretation cycle which exploits a-priori knowledge about the drawing structure and associated geometrical constraints. This is discussed in detail for an example from the area of engineering drawings. The interpretation starts with the vectorization primitives and stops when physical objects (axles, cylinders, etc.) and non-physical dimensioning objects (dimension sets, metric arrows, etc.) are recognized. It is shown that the results of drawing interpretation can be used for domain-specific tasks, e.g. dimension checking or drawing redesign. Finally, a graph-based strategy for dimension checking is described in detail.
KeywordsDrawing Interpretation Knowledge-Based System Blackboard Model
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