Lecture 9 GIS-based Urban
Modelling
9-1 Introduction
- Did not take place until the late 1980s.
- As a part of the GIS community’s efforts to
improve the analytical capabilities of GIS.
- GIS has provided modelers with new
platforms for data management and
visualization.
- Diffusion of GIS in society make models more
transparent and results to a large group of
users.
2015/10/3
Jun Liang, Geography @ UNC
1
9-2 GIS-based Urban modelling:
Current Practices
Four major approaches:
1. Embedding GIS-like
functionalities into urban
modelling packages.
-Adopted primarily by urban modellers and
spatial statisticians.
-Downside? (1) Data management, visualization.
(2) Developed by individual researchers.
2015/10/3
Jun Liang, Geography @ UNC
2
9-2 GIS-based Urban modelling:
Current Practices (Cont.)
2. Embedding urban modelling into GIS by
software vendors.
- GIS software also has begun to include
limited urban related functions, models,
etc.
Examples for ArcGIS:
Utility Network analyst,
Geostatistical analyst, Survey
Analyst, Tracking Analyst, etc.
2015/10/3
Jun Liang, Geography @ UNC
3
9-2 GIS-based Urban modelling:
Current Practices (Cont.)
3. Loose coupling.
Urban modelling and
GIS are integrated, via
data exchange using
either ASCIII or
binary data format,
among several different software packages without a
common user interface.
2015/10/3
Jun Liang, Geography @ UNC
4
9-2 GIS-based Urban modelling:
Current Practices (Cont.)
Advantages:
- Redundant programming can be avoided.
- Easy to be modified.
- Less coding. This approach may be the most
realistic method for most GIS users to conduct
modelling work..
Drawbacks:
- Most time, no main GUI.
- Data shuffling and conversion between different
packages can be tedious and error prone.
2015/10/3
Jun Liang, Geography @ UNC
5
9-2 GIS-based Urban modelling:
Current Practices (Cont.)
4. Tight coupling.
This approach
embeds certain urban
models with a
commercial GIS
software package via
either
GIS macro
or
conventional
programming.
Sui claimed – “…Such
languages are seldom powerful enough to
implement sophisticated models,…”
2015/10/3
Jun Liang, Geography @ UNC
6
9-2 GIS-based Urban modelling:
Current Practices (Cont.)
- Allow user-developed modelling libraries or
routines to be called within the normal pull-down
menu of a particular software package.
- Allow user-developed tools to be accessed by
other users (standard tools can be shared).
- Requires a well-defined interface to the data
structures held by the GIS.
- Functions/objects/classes are growing very fast,
and may need significant time in programming.
2015/10/3
Jun Liang, Geography @ UNC
7
9-2 GIS-based Urban modelling:
Current Practices (Cont.)
Two other features of the recent GIS-based urban
modelling efforts are worth noting:
1. The development and introduction of a series
of new concepts and techniques in urban
modelling - cellular automata, fractals, neural
networks, parallel processing, and genetic
algorithms, etc.
2. The rise of urban modelling applications in the
private sector, relating to marketing and
geodemographic analysis.
2015/10/3
Jun Liang, Geography @ UNC
8
9-3 Existing Problems
Problems of the urban models
- Land use policy decision support
- Interaction modeling (gravity, network, etc.)
- Simulation modeling (urban sprawl, crime
pattern, etc.)
Problems of GIS
- Open source GIS (GRASS) has more research
capabilities, no cost to share.
- Commercial GIS software is more user friendly,
good support, and more users.
2015/10/3
Jun Liang, Geography @ UNC
9
9-3 Existing Problems (Cont.)
Problems of GIS (cont.)
Map layer representation scheme is not only
temporally fixed but is also incapable of
handling overlapping features.(Sui)
2015/10/3
Jun Liang, Geography @ UNC
10
Descargar

Urban GIS Application