Transformations of spatial representation in scale dimension

Abstract

Generalization aims to reduce the amount of details in the map content. The selection of map features primarily depends on the purpose of the map and the target scale to be generalized. Once the purpose is determined, for example, a map used for general purpose (topographic map), then the only factor to drive generalization is scale. Thus the current study focuses on how the cartographic features transform in scale dimension. It is done through interviewing cartographers, analyzing text documents (e.g. production guidelines, specifications), and comparatively observing and quantifying the changes in representation of a series of different scale manually produced maps. This thesis describes an empirical study on the transformation of spatial representations in scale dimension. Six different scales of topographic maps ranging from 1:1,000 to 1:20,000 were examined for the study of road and building features in Hong Kong. Through observations and analyses, empirical facts about how classes of cartographic objects were represented on maps at different scales were recorded. The findings were quantified into several levels in terms of 'Feature Vanishing Levels', or FVL in short. Statistical analysis was undertaken to relate the FVL to several attributes of road and building features for the testing of dependencies of selection/erasion. Outcomes of the study depict the changes in representations of features affected by scale reduction, includes feature re-definition/re-classification and geometric re-shape/re-dimension. The statistical analysis illustrates the weighting of effect of attributes on transformation of spatial representation. The results conclude that road type and building area play a more important role on the transformation of road and building correspondingly, compared with other tested attributes.