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Technische Universität München
A User Perspective on Typification of Facade Features of 3D Building
Models
Mathias Jahnke
Hongchao Fan
Liqiu Meng
ICC 2009
Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
3D city model
• Buildings– Roof elements
– Facade elements
• Trees • Step structures• Streets• Textured with different kinds of pictures
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Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
The mobile device
• Limited display size• Limited computing capabilities• Limited interactivity
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Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
Drawbacks of a highly detailed city model
• High information density• Overlapping contours
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Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
Information density
• Non-photorealistic rendering (NPR) seems to be favorable– Reduces the overall graphic complexity
– Highlighting of important objects
– Artistic abstraction
– Aesthetic appeal (?)
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Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
Overlapping contours
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Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
Typification
• Fusing windows within a facade
• But applying different geometric constraints– Typification in a tendency direction
– Preserving the ratio of width and height
– Preserving distances between windows
– Preserving distances between windows and the outline of the facade
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Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
Cognition
• Cognition plays an important role for visualization
• Different gestalt laws– Proximity
– Similarity
– Continuity
– Closure
– Symmetry
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Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
Appropriate facades for typification
• Typical distribution pattern• Rectified and traced facades for evaluation
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Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
Comparison of different facade typifications
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Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
Results
Value Summarization
mostimportant
10,0 keeping the shape conform
7,0Keeping distances between window/window and window/outline
5,3keeping distances between windows/outline
4,7keeping distances between window/window
less important
4,6typification of windows only in tendency direction
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Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
Conclusion & future work
• Is a good starting point for further investigations• The approach seems to be appropriate for facade
generalization• The user have to be taken into account
• Applying the results to a 3D city model• Different viewing directions• For future evaluations increasing the group of
participants
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Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
Outlook
• Applying the results to 3D city model
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Technische Universität München
Faculty of Civil Engineering and GeodesyDepartment of Cartography
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