Knowledge-based hierarchical sketch understanding

This article presents a knowledge-based framework for sketch understanding. Compared to traditional sketch understanding systems, it has two significant features: (1) knowledge-based. This makes the system independent of applied domain. Users can easily design an ontology-based domain knowledge base to guide the understanding process. (2) hierarchical approach. The sketch understanding process is divided into three phases: token recognition, salient symbol recognition and integral recognition. During all these phases, domain knowledge is used as a guider. In addition, a domain knowledge base of UML class diagram is presented as a case study of this framework, in which the details of how to design ontology-based knowledge base and how to implement a hierarchical recognition are given. Some UML class diagram sketches are used as experiments, which produce satisfactory results.