It is commonly recognized that free-hand sketch maps are influenced by cogni- tive impacts and therefore sketch maps are incomplete, distorted, and schematized. This makes it difficult to achieve a one-to-one alignment between a sketch map and its corre- sponding geo-referenced metric map. Nevertheless, sketch maps are still useful to commu- nicate spatial knowledge, indicating that sketch maps contain certain spatial information that is robust to cognitive impacts. In existing studies, sketch maps are used frequently to measure cognitive maps. However, little work has been done on invariant spatial in- formation in sketch maps, which is the information of spatial configurations representing correctly the real world. We aim to study such information from a cognitive perspective. This paper first presents basic spatial objects identified in sketch maps and then introduces sketch aspects that capture invariant spatial information. The accuracy and reliability of these aspects were evaluated by a human study. We collected sketch maps from partici- pants, extracted and measured spatial relations of identified spatial objects, and in the end analyzed the accuracy and statistical significance of these relations. Based on the statisti- cal survey, we propose in this paper a set of seven sketch aspects that constitute invariant spatial information, along with a spatial analysis method to measure them. The findings of these aspects help to understand which spatial information is preserved under the trans- formation from the physical world to human sketch maps.
['Jia Wang', 'Angela Schwering']
Invariant spatial information in sketch maps — a study of survey sketch maps of urban areas