Qualitative analysis of sketched route maps: translating a sketch into linguistic descriptions

In this correspondence, we introduce our work on sketch understanding, focusing here on the analysis of a sketched route map. A route map is drawn to help someone navigate along a path for the purpose of reaching a goal. A hand-sketched route map does not generally contain complete map information and is not necessarily drawn to scale, but yet it contains the correct qualitative information for route navigation. Here we propose a methodology for extracting a qualitative model of a sketched route map, based on human navigation strategies, using spatial relationships. Linguistic descriptions are generated from the sketch, both in the form of detailed descriptions at discrete path steps and also as a high-level route description. To describe the path linguistically, one must first be able to understand the path in a qualitative sense. We assert that the translation of a sketch into linguistic descriptions illustrates that the essential qualitative path knowledge has been extracted. The methodology is demonstrated using example sketches drawn on a handheld PDA.