Presentation at the 3AMIGAS workshop

1. A Survey of
Procedural Methods for
Terrain Modelling
Ruben Smelik
Klaas Jan de Kraker
Saskia Groenewegen
Tim Tutenel
Rafael Bidarra

2. Motivation for Automated Terrain Modelling
• Game worlds are increasing in size, detail and visual realism
• Manual design requires effort, time, 3D modelling skills, money, etc.
Wolfenstein 3D (id, 1992) Crysis (Crytek, 2007)
2 Amsterdam,Tuesday, June 16 2009

3. Procedural content generation
• Content generation procedures based on rules, random numbers, etc.
• Also know as data amplification algorithms:
• Few parameters => large amount of content
• Common techniques:
• Fractals
• Rewriting systems
• Simulations
• Advantages:
• Saves effort / time / money
• Variation through randomness
• Storage
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4. Current limitations
• Too random, user has no real control over outcome
• Trial and error
• In-depth knowledge and experimentation required
• Unintuitive parameters, e.g. “persistence”
• Methods have not (yet) been integrated properly
4 Amsterdam,Tuesday, June 16 2009

5. Topics in Procedural Terrain Modelling
1. Earth (height-maps, eroded landscapes)
2. Water (oceans, rivers and lakes)
3. Vegetation (plant models, distribution)
4. Road (networks)
5. Urban (buildings, facades)
5 Amsterdam,Tuesday, June 16 2009

6. Earth - Height-map Generation
• Subdivision
Miller, G. S. P. (1986)
The Definition and Rendering of Terrain Maps.
• Fractal Brownian Motion (using Perlin Noise)
Musgrave, F. K. (1993)
6 Methods for Realistic Landscape Imaging. Amsterdam,Tuesday, June 16 2009

7. Earth - Erosion Simulation
• Thermal erosion
Benes, B. and Forsbach, R. (2001)
Layered Data Representation for Visual Simulation of
Terrain Erosion.
• Fluvial erosion
Anh, N. H., Sourin, A., and Aswani, P.
(2007)
Physically based Hydraulic Erosion
Simulation on Graphics Processing Unit.
7 Amsterdam,Tuesday, June 16 2009

8. Earth - Commercial Tools
TerraGen (Planetside Software)
8 Amsterdam,Tuesday, June 16 2009

9. Water - Rivers, Oceans and Lakes
Belhadj, F. and Audibert, P. (2005)
Modeling Landscapes with Ridges and Rivers: Bottom Up Approach.
9 Amsterdam,Tuesday, June 16 2009

10. Vegetation - Plant Models
• L-Systems (symbolic rewriting grammar)
Měch, R., Prusinkiewicz, P. (1994).
Visual models of plants interacting with their environment.
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11. Vegetation - Distribution Simulation
Realistic distribution of plants
based on an ecosystem model
Deussen, O., Hanrahan, P., Lintermann, B., Měch, R., Pharr, M., and Prusinkiewicz, P. (1998).
Realistic Modeling and Rendering of Plant Ecosystems.
11 Amsterdam,Tuesday, June 16 2009

12. Vegetation - Commercial tools
SpeedTree (IDV, inc.)
XFrog (Greenworks)
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13. Road - Network Patterns
Sun, J., Yu, X., Baciu, G., and Green, M. (2002).
Template-based Generation of Road Networks for Virtual City Modeling.
13 Amsterdam,Tuesday, June 16 2009

14. Road - Network Generation
• L-Systems with validity checks, slope constraints and population-
oriented rules
Parish, Y. I. H. and Müller, P. (2001).
Procedural Modeling of Cities.
14 Amsterdam,Tuesday, June 16 2009

15. Urban - Building Grammars
• Split and Shape grammars
Müller, P., Wonka, P., Haegler, S., Ulmer, A., and Gool, L. V. (2006)
Wonka, P., Wimmer, M., Sillion, F., and Ribarsky, W. (2003)
Procedural Modeling of Buildings.
Instant Architecture.
15 Amsterdam,Tuesday, June 16 2009

16. Urban - Commercial Tools
“Random” roads and city
Virtual Pompei
16 CityEngine (Procedural, inc.) Amsterdam,Tuesday, June 16 2009

17. Integrated Procedural Terrain Modelling
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18. Current Results
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19. Conclusions
• Procedural modelling is an active research area with many
developments
• Focus shifts from height-map generation to urban environments
• Research directions:
• Performance
• GPU programming
• More detailed urban environments
• E.g. building interiors
• Integrated frameworks with intuitive controls
19 Amsterdam,Tuesday, June 16 2009