Using Virtual Cities to Plan Real Cities

1
Using Virtual Cities to Plan Real Cities

• A Case Study
• Using the Virtual Terrain Project
• In Hangzhou, China

Dr. Michael Flaxman Lecturer in Landscape
Planning Harvard Graduate School of Design
Ben Discoe Lead Developer, Virtual Terrain
Project The Open Planning Project (TOPP)
2
Cast of Characters
15 Graduate Students in Architecture, Landscape
Architecture Planning One Semester
Interdisciplinary Studio (double
course) Faculty Carl Steinitz (Architecture
Landscape Architecture) Mike Flaxman (Planning,
GIS Visualization) Ben Discoe, Lead Developer,
VTP (not pictured)
3
Study Area Location
Southeastern China 2 hours SW of Shanghai
4
Public Image of the Westlake and Hangzhou
5
Hangzhou 2000
One of the Most Prosperous Cities in China 6
Million People Population Doubling in 20
Years 15X Auto Ownership Expected
6
Design Strategy

• Conclusion of prior Harvard study
• To protect the West Lake, new development should
  be directed away from it and toward the river to
  the South.
• Build New City Center Along River
• Make this area more attractive to development
  than the edge of the West Lake

7
Basic Task Propose Evaluate Alternative Plans
for Hangzhou 2020
Each Alternative Accommodates Projected Growth
(Same Program) Evaluate the Visual, Economic
Environmental Consequences Present Results to the
General Public in Form which Fosters Productive
Discussion
8
Problem Summary

• Design Challenge How to Develop and Evaluate
  Compelling Alternatives for Large Urban Areas
• Where to place strategic public investments in
  transportation infrastructure and civic buildings
• Where to allow various land uses and densities /
  heights
• Need to establish open space network planning

• Technical Challenge How to Visualize Alternative
  Futures for Large Cities and Regions
• Efficiently generating models of current
  conditions
• Visualizing multiple alternative plans in 3D
• Visualizing detailed design in broader context
• Workflow must facilitate top down design

9
Conventional Approaches to City Representation
for Planning

• Sketches -gt maps
• Single-use zoning representing classes of
  legally-permitted use
• Building heights implicit in zoning

10
Problems with Conventional Representation

• Nobody understands the maps except (perhaps) the
  planner
• Basically too abstract all concerned prefer
  representation with building massings to provide
  sense of scale
• Two dimensional representation of a truly 3D
  problem

11
Visualization Goals
Visual representation of function, size and
locations (not realism but natural scene
paradigm) Represent some individual buildings
and neighborhood patterns A good working model,
not just a polished final rendering
12
Challenge 1 Number and Diversity of Elements

• Landscape Components
• Terrain
• Buildings
• Roads
• Vegetation
• Water
• Lighting/Atmosphere

Any large landscape is likely to contain all of
these components. The relative proportion will be
location-specific, but each component needs an
efficient representation.
13
Challenge 2 Interactivity
Work done in parallel by 20 students working on
PCs (single high-end visualization system not
practical) Students and design critics need to
be able to view work from any camera
angle Design revisions should require editing at
the level of the critique (changing zoning rather
than manually moving 3000 buildings)
14
Potential RealtimeCity Visualization Approaches

• GIS Visualization Systems
• ArcScene, ERDAS VirtualGIS
• Game Engines
• VRML /GeoVRML
• Commercial flight simulation generators
• General conclusion
• Many technical solutions were available, but no
  single available package was suitable for
  interactive city design with real GIS/CAD

15
Why The Virtual Terrain Project?

• Supports most common GIS formats
• CLOD terrain simplification allows realtime
  performance on normal PC hardware
• Can generate buildings procedurally based on
  footprints
• Integrates CAD models where available
• Cross Platform
• Open Source, so both free and extensible

16
VTP Foundations

• Built atop three major libraries
• Open Scene Graph
• High Performance, OpenGL-based
• Reads Many 3D Formats OpenFlight, 3DS
• wxWindows
• Provides mature cross-platform GUI (Linux,
  Windows, MacOS)
• GDAL (Geographic Data Abstraction Library)
• Reads/writes most GIS formats
• Deals with Map Projections

17
VTP Visualization Process

• Establish data meaning representation options
• Using Builder for 2D GIS/Image Data
• Culture Editor for 3D and proxies
• View/Edit Using Runtime Enviro

18
Production Pipeline 1 Base Data

• Current Conditions
• Base data from 1m satellite scene
• Existing building footprints from 11000 CAD
• Elevation from 110K contours spot elevations

19
Production Pipeline 2 Buildings

• Developed Building Typology
• Developed custom ArcView scripts to place
  template building footprints with attributes
• Generic buildings derived procedurally from
  footprints in Builder
• Custom buildings/bridges developed in CAD /
  surfaced in 3DS. Insert locations specified in
  GIS.

20
Production Pipeline 3 Terrain Ground Cover

• Grading plans developed in GIS using ArcView Tin
• Surface cover changes specified in GIS
• Exported from GIS as an image file (BMP)

21
Production Pipeline 4 Vegetation

• Planting plans done by landscape architects in
  GIS (placing stems plant ID attribute)
• Street trees generated procedurally in GIS based
  on road type

22
Results Process

• Efficient Four plans in four weeks
• a good plan is a done plan
• Students with no prior 3D visualization
  experience were able to productively use the
  tools
• Effective Visualizations influenced design
  choices
• Building densities of first round proposals
  looked like Cleveland so adjusted upward
• Visualization of greenspace and street trees had
  large impact in public reviews in China

23
Results of GIS Templates to 3D Strategy

• Weaknesses
• No good tools for building footprint
  generation/alignment
• Generating grading plans using ArcView very
  tedious
• Some design best done in 3D.

• Strengths
• Efficient for large areas
• Good, cleanly-attributed data
• GIS intermediate products useful

24
Results VTP Strengths

• Supports all major landscape elements
• billboard vegetation, CLOD terrain
• Procedural CAD buildings
• GIS integration facilitated top-down design and
  revisions

• Simple navigation interface
• Powerful real-time visualization technologies for
  work on standard commodity hardware

25
Results VTP Weaknesses(for use in Interactive
Planning)

• Constraints on terrain size and ground plane
  resolution
• Multiple file conversions required for some
  design changes (no auto-update/build)
• Lack of integration of feature types
  (particularly roads terrain)
• GIS integration was one way (GIS-gtVis) rather
  than round trip (no Vis-gtGIS)

26
General Conclusions about City Regional
Visualizations for Planning Use

• Chosen technique must efficiently represent
  common objects types
• GIS/database essential for effective real-world
  visualization creation/management
• Procedural modeling greatly facilitates both
  creation and updates
• Inter-object 3d topology/constraints very
  challenging

27
Next Steps

• Beyond aesthetics - visualizing consequences
• Economic, Biodiversity, Water Quality
• Scenario Comparison Interface
• Visualize differences using crossfade or split
  screen
• Internet integration
• Easy data acquisition from web map servers
• Facilitate sharing of building models,
  ecosystems, etc.
• Better pattern generation tools

28
For More Information

• On the Hangzhou Project
• http//www.gsd.harvard.edu/gsd98mf2
• The Virtual Terrain Project
• http//vterrain.org/

29
Future Directions

• Interface Enhancements
• Incorporate Viewpoint and Animation Path
  Enhancements
• Ecosystem/vegetation import and setup
• Improve dynamic scene updating in Enviro

30
Future Directions 2

• Better integration with GIS
• Make VTP Client of OpenGIS Web Map Servers
• Facilitate GIS lt-gt VTP Ground plane transfer
• Allow edits in 3D, saving to GIS
• Improvements to Procedural Generation
• Dynamic modification of buildings based on
  attribute changes (currently only on import)
• Semi-random placement with offset from linear
  features (buildings along road, vegetation along
  street, etc.)
• Stratified random vegetation placement relative
  to terrain attributes

31
Future Directions 3

• Efficiency and Quality Enhancements
• Support Impostors for buildings
• Support tiled/paged terrain with textures
• Higher-quality rendering modes for non-realtime
  use (or geomorphed with steady camera)
• Focus on Community and Environmental Planning