Visualisation of Settlements Over Large Changes In Scale
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Date
2006Author
Chaudhry, Omair
Mackaness, William
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Abstract
This paper explores the application of map generalisation techniques in the creation of small
scale mapping (1:250,000) directly from large scale data (1:1250 and 1:2500). Small scale
mapping provides a synoptic overview. At 1:250,000 scale, it is not that there is less
information contained in the map, rather that we see fundamentally different information and
relationships – broad-brush information between higher order phenomenon. The evaluation
criteria used at this scale are quite different from those used at large scale. This paper
describes a methodology by which small scale mapping is derived directly from the large
scale (without generating intermediate results) using simple generalisation techniques. The
approach illustrated in this case study, creates city boundaries based on simple buffering of
building features, and derivation of the single polygon surrounding clusters of buildings over
a threshold size. The hull is simplified, small internal polygons removed. The algorithm was
applied to large and small conurbations alike. The results obtained via this method were
evaluated against paper maps. Initial results point to refinement of this technique.