Date post: | 08-Jul-2015 |
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Wall Grammar for Building Generation
Mathieu Larive and Véronique Gaildrat
Visual Objects, from Reality To EXpressionhttp://www.irit.fr/-Equipe-VORTEX
Oktal Synthetic Environmenthttp://www.oktal-se.fr
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Contents
• Introduction
• Frontage Templates
• Groundwork and Roof Templates
• Results and Discussions
• Conclusion and Future Work
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Problem
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Goals
• Quickly create a plausible (geo-typic) city around an already modelized zone (geo-specific)
• Reach a level of detail satisfactory enough for a navigation at ground level:– modeling of the buildings’inside– geometric modeling of the urban furniture
→ usage of automatic techniques inside AGETIM
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Generation steps
• Hierarchical division of city generation process in seven steps [Larive2005]
• Each step can be seen as a logical LoD
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Contents
• Introduction
• Frontage Templates
• Groundwork and Roof Templates
• Results and Discussions
• Conclusion and Future Work
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Frontage Templates
• A frontage template contains a primary wall and possibly a background material
• A frontage template can be seen as a style sheet that describes:– wall rendering– possible dimensions and kinds of windows and doors
(described as textures or 3D objects)– how to place these elements on the building
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Frontage Templates
• Formal grammar representation [Wonka2003]
• 2,5 dimensions paramatric wall grammar
Position rulesRepetition rules
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Frontage Templates
• Wall Panel
– the unique terminal symbol of our grammar
– various parameters:• texture
– Background– Decoration
• 3D object• possible dimensions
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Frontage Templates
• Extruded Wall– depth (positive or not)– depth faces generation
boolean – EW → W
• Bordered Wall– four margins– resize policy– BW → W
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Frontage Templates
• Wall Grid– Contains an unique
child wall– Repetition
• Vertical• Horizontal• Both
– Controlled by two cardinality intervals
– WG → Wnm
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Frontage Templates
• Wall List– Several child walls– Orientation (exclusive)
• Vertical• Horizontal
– WL → W1W
2...W
n
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Frontage Templates
• The combination of those different walls in a tree-like hierarchy allows the user to build simple or complex frontage templates
• Use of repetition schemes on every part of our frontages (wall grid)
• Usage of previously generated 3D objects (such as balconies or cornices)
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Frontage Templates
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Contents
• Introduction
• Frontage Templates
• Groundwork and Roof Templates
• Results and Discussions
• Conclusion and Future Work
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Groundwork and Roof Templates
• Groundwork templates– Z-min– Z-max– Extruded
Z-min Z-max Extruded
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Groundwork and Roofs Template
• Roof templates– Based on the Straight
Skeleton method [Felkel1998]
– One, two or four slopes– Overhang (4 types)– Currently, 10 various
roof types
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Contents
• Introduction
• Frontage Templates
• Groundwork and Roof Templates
• Results and Discussions
• Conclusion and Future Work
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Results
• Various buildings on one building footprint
94 faces 350 faces 5600 faces
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Results
• Large scale urban area
17 362 buildings, 920 182 faces generated in less than 8 mn
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Conclusion
• Able to generate buildings on any kind of footprint– convex, non-convex, non-plane, even with holes
• Generated buildings are valid – geometrically (no hole, no overlapping face, no empty
frontage -blind frontages-)– no window or door on a frontage edge
• Once a building template is finished and robust, it can be immediately reused (ready-to-use building template library)
• Control of the geometric complexity, according to the user hints
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Future Work
• Finalize the building template editor
• Usage of the Urban Land Use Model– Road network generation– Creation of lots and
building footprints
• Integration of all the various generation steps inside the same process