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