Hagen Zanker Iccsa2008

Map comparison methods for comprehensive assessment of geosimulation models

Alex Hagen-Zanker1,2, Pim Martens3

4. Research Institute for Knowledge Systems5. Urban Planning Group, TU/e6. International Centre for Integrated

assessment & Sustainable development

/ Urban Planning Group PAGE 2ICCSA 2008

Assessing GeoSimulation models

• GeoSimulation• Unfolding spatial patterns

(complex & non-linear)• Heterogeneous landscape

(boundary condition)• Good modelling practice

• Calibration• Validation• Model selection / development• Sensitivity analysis• Global behavioural tests

• Map comparison• Agreement between model and

realitysource: www.geosimulation.com


Cellular Automata land use model

Time LoopTime Loop

&&

Stochastic perturbation

0 0.5 1

randvt ln1

Zoning

&

&

Accessibility

Transition-potential

=

Transition RuleTransition RuleChange cells to land-use for which they have the

highest transition potential until Regional

demands are met.

&

Suitability

Land use

& Interaction weights

Land use at time T+1


Geographical scale

• Local → individual locations• Focal → moving window • Global → whole landscape

Local GlobalFocal

Agreement

1st map pair

2nd map pair

Geographical scale

Distinct

Identical

1st map pair

2nd map pair

Moving window / kernel


Structure & Presence

• Similar in terms of presence

• Similar in terms of structure


Comparison framework

• Global presence not of interest• exogenous model input

• Local structure not possible• Single cell has no internal spatial configuration

Cluster size distributionMoving Window Patch size-Structure

-Moving Window EuclideanKappaPresence

GlobalFocalLocal


Local presence: Kappa

• Transition table the heart of local presence comparison• Kappa statistic• User / producer accuracy

25001042511501995Σ

75190848

23309618119

1651119261

202774154321767

Σ

Kappa = 0.38


Focal presence: Euclidean distance

Mean Euclidean Distance


Focal structure: Patch size

Map Patch size Moving window

Difference

Root Mean Squared Error


Global structure: Cluster size distribution

• Kolmogorov-Smirnov distance expresses difference in distributions without any assumptions


Reference level for the results

• Random Constraint Match• Minimize change given initial situation• Subject to total area constraints

Before

After+29

+18

-15

-32

Generated reference map


Results: Local presence (Kappa)

0.900.910.910.92Nature

0.810.730.770.77Business

0.860.830.850.87Residential

0.910.880.890.91Agricultural

0.890.870.880.90Overall

ReferenceModelReferenceModel

Validation ’96-’00Calibration ’89-’96

+ -


Results: Focal presence & structure

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0 2 8 32 128 512Radius (500 m. cells)

Model

Reference

0

0.02

0.04

0.06

0.08

0.1

0 2 8 32 128 512Radius (500 m. cells)

0

5

10

15

20

25

30

35

0 2 8 32 128 512Radius (500 m. cells)

0

5

10

15

20

25

30

35

40

0 2 8 32 128 512Radius (500 m. cells)

Calibration period 1989-1996

Validation period1996-2000

PresenceEuclidean

StructurePatch size

+

+

-

- +


Results: Global – Cluster size distribution

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

0.160

Residential Business Nature

Model

Reference

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.070

0.080

0.090

0.100


0.000

0.050

0.100

0.150

0.200

0.250


Calibration ’89 - ’96 Validation ’96 - ’00 Long term 2000 - 2030

• Calibration based on comparison 1996-1996• Validation based on comparison 2000 - 2000• Long term based on comparison 2000 – 2030

+ + +


Results: Validation overview

• Strengths and weaknesses according to understanding of CA• Poor performance explained by short period and data quality• In the meanwhile, others found better results with same model

Cluster size distributionMoving Window Patch size-Structure

-Moving Window EuclideanKappaPresence

GlobalFocalLocal

++

-- -+


Conclusion

• Assessing GeoSimulation model requires geospatial perspective• Spatial scale (Local – Focal – Global)• Spatial configuration (Structure – Presence)

• Interpretation of results requires reference level• Naïve predictor• Boundary conditions / constraints

• Otherwise?• Unbalanced judgement• Frustrating scientific progress


Thanks for your attention

• Alex Hagen-Zanker - [email protected] • Map Comparison Kit - www.riks.nl/mck

• Free software• User manual • Training materials• Publications

• Software developed for and shared by:

mailto:[email protected]

http://www.riks.nl/mck

Technology

Hagen Zanker Iccsa2008