An adjacency grammar to recognize symbols and gestures in a digital pen framework

Abstract

The recent advances in sketch-based applications and digital-pen protocols make visual languages useful tools for Human Computer Interaction. Graphical symbols are the core elements of a sketch and, hence a visual language. Thus, symbol recognition approaches are the basis for visual language parsing. In this paper we propose an adjacency grammar to represent graphical symbols in a sketchy framework. Adjacency grammars represent the visual syntax in terms of adjacency relations between primitives. Graphical symbols may be either diagram components or gestures. An on-line parsing method is also proposed. The performance of the recognition is evaluated using a benchmarking database of 5000 on-line symbols. Finally, an application framework for sketching architectural floor plans is described. © Springer-Verlag Berlin Heidelberg 2005.