The Accuracy of Sketched Spatial Relations: How Cognitive Errors Influence Sketch Representation

Wang, J.; Schwering, A.

Abstract

Compared to verbal and textual language, sketch maps are an intuitive and effective way to communicate about spatial information. Untrained users can use sketch maps to easily interact with GISs, e.g., to query the spatial database by drawing freehand sketches. However, in these handdrawn sketches, errors such as straightening, direction and shape distortions are inevitable and are a natural result of schematization, distortion and abstraction in perceptual and cognitive processes. These errors affect the accuracy of sketched spatial properties and spatial relations, e.g., topological relations or cardinal directions, which make sketch maps not as accurate as metric maps which is based on exact measurements. This paper analyzes typical cognitive errors in sketch maps and evaluates Egenhofer’s query-by-sketch approach for sketch map formalization with respect to these errors. We conduct an experiment that demonstrates how typical cognitive errors lead to false formalizations in the query-by-sketch approach and suggest how the formalization could be improved. We aim at developing an approach for sketch representation which is able to deal with cognitive errors, incomplete information, and capable of abstracting useful spatial relations at the right level of granularity for future spatial reasoning tasks.

Projects the publication originates from