Efficient derivation and caricature of urban settlement boundaries - PowerPoint PPT Presentation

Efficient derivation and caricature of urban settlement boundaries for 1:250k Andreas Reimer and Christian Kempf Universit¨ at Heidelberg 1 / 28

Can schematisation techniques be used for medium scale generalisation? 2 / 28

Huh? Schematisation? 3 / 28

Huh? Schematisation? Definition We define schematisation in cartography as a process that uses cartographic generalisation operators in such a way as to produce diagrams of a lower graphical complexity compared to maps of the same scale; the process aims to maximise task-adequacy while minimizing non-functional detail. In contrast, traditional cartographic generalization can be understood as trying to maximise functional detail with task-adequacy (in the form of legibility) as a constraint. Schematisations use many unorthodox design principles → carricature etc. 3 / 28

Why Strategi? 250k legacy product manually updated no relation to OS Master Map data geometrically fitted to generalised base data 4 / 28

Why Strategi? 5 / 28

Why Strategi? 6 / 28

Approach find out target design rules/constraints empirically reduce input complexity in model generalisation redraw geometries in cartographic generalisation 7 / 28

Observations... Strategi 2500 2000 1500 quantity 1000 500 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 number of nodes/perimeter [linelength mm] 8 / 28

Input from OS Master Map 9 / 28

Selection 10 / 28

Buffer 11 / 28

Union 12 / 28

Selection by size 13 / 28

Simplification: Visvalingam-Whyatt 14 / 28

Angular schematisation 15 / 28

Input and result 16 / 28

Result in context 17 / 28

At viewing scale 18 / 28

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