A model-based recognition engine for sketched diagrams

  • Authors:

  • Florian Brieler;Mark Minas

  • Affiliations:

  • Universität der Bundeswehr München, Department of Computer Science, 85577 Neubiberg, Germany;Universität der Bundeswehr München, Department of Computer Science, 85577 Neubiberg, Germany

  • Venue:
  • Journal of Visual Languages and Computing
  • Year:
  • 2010

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Abstract

Many of today's recognition approaches for hand-drawn sketches are feature-based, which is conceptually similar to the recognition of hand-written text. While very suitable for the latter (and more tasks, e.g., for entering gestures as commands), such approaches do not easily allow for clustering and segmentation of strokes, which is crucial to their recognition. This results in applications which do not feel natural but impose artificial restrictions on the user regarding how sketches and single components (shapes) are to be drawn. This paper proposes a concept and architecture for a generic geometry-based recognizer. It is designed for the mentioned issue of clustering and segmentation. All strokes are fed into independent preprocessors called transformers that process and abstract the strokes. The result of the transformers is stored in models. Each model is responsible for a certain type of primitive, e.g., a line or an arc. The advantage of models is that different interpretations of a stroke exist in parallel, and there is no need to rate or sort these interpretations. The recognition of a component in the drawing is then decomposed into the recognition of its primitives that can be directly queried for in the models. Finally, the identified primitives are assembled to the complete component. This process is directed by an automatically computed search plan, which exhibits shape characteristics in order to ensure an efficient recognition. In several case studies the applicability and generality of the proposed approach is shown, as very different types of components can be recognized. Furthermore, the proposed approach is part of a complete system for sketch understanding. This system not only recognizes single components, but can also understand sketched diagrams as a whole, and can resolve ambiguities by syntactical and semantical analysis. A user study was conducted to obtain recognition rates and runtime data of our recognizer.