procedural modeling of cities slides siggraph2001

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Procedural Modeling of Cities: 

Procedural Modeling of Cities Pascal Müller Central Pictures Switzerland Yoav Parish ETH Zurich Switzerland

The City Engine System: 

The City Engine System Procedurally creates complex city models. Cities consist of: Street maps Buildings Facade textures

Example Zurich-London-Paris: 

Example Zurich-London-Paris

Example Manhattan: 

Example Manhattan

Example Manhattan 2259: 

Example Manhattan 2259


Overview Introduction Motivation and system pipeline L-Systems From streets to buildings Textures and results Rendering of the results


Motivation Many applications in entertainment, simulation and visualization Cities as virtual „backdrops“ are hard to model by hand Procedural methods have been used to model complex environments

Related Work: 

Related Work Mostly satellite-imagery based systems e.g. Henricsson, Streilein, Gruen; 1996 Work on visualization of large data sets e.g. Davis, et al.; 1999 Similar projects are still in the making Yap; 1998

System Pipeline: 

System Pipeline

Module 1: Streetmap Creation: 

Module 1: Streetmap Creation Input: Image maps, parameters for rules Output: A street graph for interactive editing

Module 2: Division into Lots: 

Module 2: Division into Lots Input: Street graph, area usage map Output: Polygon set of allotments for buildings

Module 3: Building Generation: 

Module 3: Building Generation Input: Lot polygons, age map and zone plan Output: Building strings with additional info

Module 4: Geometry and Facades: 

Module 4: Geometry and Facades Input: Strings and building type Output: City geometry and facade texture (procedural shader)


L-Systems Generation of plants Prusinkiewicz, Lindenmayer; 1990 Environment-sensitive Prusinkiewicz, James, Mech; 1994 Interaction (Open L-System) Mech, Prusinkiewicz; 1996 Ecosystems Deussen, et al.; 1998

L-Systems for Streets: 

L-Systems for Streets Grouping parameters of different street patterns Hierarchical influences: global goals and local constraints

Extended L-Systems: 

Extended L-Systems Template successor defines 3 branches Parameters fields are unassigned

Extended L-Systems: 

Extended L-Systems Initial parameter settings Design goal

Extended L-Systems: 

Extended L-Systems Parameter value correction Influenced by local environment

Global Goals: 

Global Goals Could be a planned urban design Different goals in the same city Controlled by image map (user input)

Local Constraints: 

Local Constraints Environment-sensitivity for legal streets Self-sensitivity for closed loops

Division into Lots: 

Division into Lots Lot area depends on: Land Use map Population density Building height Access to street

Procedural Buildings: 

Procedural Buildings Modeled with a common L-System L-System modules consist of geometric operations like extrusion

Facade Textures: 

Facade Textures Division into simple grid-like structures Structures can be layered

Layered Textures: 

Layered Textures Two base functions form a layer Every layer defines a facade element

Layering of Planes: 

Layering of Planes Stacked layers for facade texture Functions between layers model relation between facade elements

Animated Examples: 

Animated Examples

Future Work: 

Future Work Temporal development of an urban area Function based grammar of buildings Bring life into the cities


Acknowledgments Prof. Markus Gross ETH Zurich, Switzerland Christian Iten School of Art Zurich, Switzerland Jessica Bernatschek University of Zurich, Switzerland Hanspeter Brunner ETH Zurich, Switzerland

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