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 Geodesy Department of Cartography 3D city model Buildings –Roof elements –Facade elements Trees Step structures Streets Textured with different kinds of pictures 2

Technische Universität München Faculty of Civil Engineering and Geodesy Department of Cartography The mobile device Limited display size Limited computing capabilities Limited interactivity 3

Technische Universität München Faculty of Civil Engineering and Geodesy Department of Cartography Drawbacks of a highly detailed city model High information density Overlapping contours 4

Technische Universität München Faculty of Civil Engineering and Geodesy Department 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 (?) 5

Technische Universität München Faculty of Civil Engineering and Geodesy Department of Cartography Overlapping contours 6

Technische Universität München Faculty of Civil Engineering and Geodesy Department 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 7

Technische Universität München Faculty of Civil Engineering and Geodesy Department of Cartography Cognition Cognition plays an important role for visualization Different gestalt laws –Proximity –Similarity –Continuity –Closure –Symmetry 8

Technische Universität München Faculty of Civil Engineering and Geodesy Department of Cartography Appropriate facades for typification Typical distribution pattern Rectified and traced facades for evaluation 9

Technische Universität München Faculty of Civil Engineering and Geodesy Department of Cartography Comparison of different facade typifications 10

Technische Universität München Faculty of Civil Engineering and Geodesy Department of Cartography Results ValueSummarization most important 10,0keeping the shape conform 7,0 Keeping distances between window/window and window/outline 5,3 keeping distances between windows/outline 4,7 keeping distances between window/window less important 4,6 typification of windows only in tendency direction 11

Technische Universität München Faculty of Civil Engineering and Geodesy Department 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 12

Technische Universität München Faculty of Civil Engineering and Geodesy Department of Cartography Outlook Applying the results to 3D city model 13

Technische Universität München Faculty of Civil Engineering and Geodesy Department of Cartography 14