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: 

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

Motivation: 

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: 

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: 

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