Essentials of Automations: Optimizing FME Workflows with Parameters
Urban Monitoring Using NetKDE and VGI
1. Urban Monitoring Using NetKDE and VGI
Network Based Kernel Density Estimation on
Volunteered Geographic Information Applied to Baghdad, Iraq
Nicolas Lachance-Bernard, Timothée Produit and Loïc Gasser
Geographic Information Systems Laboratory
Ecole polytechnique fédérale de Lausanne, Switzerland
7th VCT Virtual Cities and Territories Conference
October 11th – 13th 2011, Lisbon, Portugal
NLB-TP-LG / p.1 Urban monitoring using NetKDE and VGI: NetKDE, VGI applied to Baghdad, Iraq
2. Content
• Context
• (Network based) Kernel Density Estimation
• Background Case Studies
Barcelona, Ljubljana, Geneva, Baghdad
• Baghdad
Spatio-temporal multi-dimension analysis
• Conclusion and Further research
NLB-TP-LG / p.2 Urban monitoring using NetKDE and VGI: NetKDE, VGI applied to Baghdad, Iraq
3. Context
• Problematic
– Fact
Spatial events location influenced by urban forms
– Principal need
Adapting density estimation for graph constrained space
– Goal
Spatio-temporal monitoring of urban dynamics
• Challenges
1. To use very large datasets
2. To decrease processing times compared to out-of-the-box GIS
3. To develop multi-scale approaches
4. To develop visualization methods
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4. Network based Kernel Density Estimator
KDE NetKDE
Source: Produit et Lachance-Bernard 2009, 2010
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5. KDE vs. NetKDE
KDE NetKDE
Source: Produit and Lachance-Bernard, 2009/2010
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6. Case Studies 2009-2011
Barcelona Ljubljana Geneva Baghdad
(2009/2010) (May 2011) (June 2011) (June 2011)
Network (Agency) 20 km2 (OSM) (Agency) (OSM)
Segments 11,200 8,100 10,800 66,600
Events Eco. Activities Cyclist GPS Eco. Activities War records
Locations 166,300 314,200 15,000 93,100
Class 1 1 12 16 + Weights
Grid 200m 100m 100m 20m 200m 50m
50m 20m 10m -
Gridpoints 160,000 310,000 22,600 - 360,000
Buildings - - 70,000 -
Bandwidths [20m,6000m] [40m,1000m] [200m, 3000m]
-
KDE (Steps) (20m) (20m) (100m)
Bandwidths [100m,1000m] 60m 100m 500m [200m, 3000m]
NetKDE (Steps) (100m) 200m 400m (100m)
Processing 9 computers 1 computer 1 computer 1 computer
times 500h 18h + 77h 15h & 20h &
KDE + NetKDE 5min/class 5min/class
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7. Barcelona Eco. Activities: Grid resolution variations (band. 500m)
H
KDE grid 200m NetKDE grid: 200m
L
KDE grid 50m NetKDE grid: 50m
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8. Barcelona Eco. Activities: KDE vs. NetKDE (10m grid, 500m band.)
H
KDE (ZOOM) NetKDE (ZOOM)
L
KDE NetKDE
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9. Ljubljana
GPS Bike:
NetKDE
20m grid
Bandwidths
A)60m
B)100m
C)200m
D)400m
*Deciles distribution
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10. Baghdad
Case Study
Data
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11. Baghdad Case Study Data: Guardian database
Report ID Report
Information
Date (dd.mm.yyyy) Description
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13. Baghdad IED: NetKDE
NetKDE 800m bandwidth NetKDE 1400m bandwidth
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14. 3D Spatio-temporal KDE*
• Proposed by Demsar and Virrantaus (2010)
based on space-time cube by Hägerstrand
• 3D KDE function
3D Epanechnikov kernel
function
* Implemented by Loic Gasser, Timothée Produit and Nicolas Lachance-Bernard
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15. Baghdad IED explosions KDE
January 2004 - December 2009
• 2,652 events - 1,030 km2 - 76 steps, 1500m KDE
• 1 day equivalent to 10 meters
Source: Loic Gasser, 2011
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16. Conclusion
• NetKDE for spatio-temporal trends, hotspots, …
– Barcelona: playing with scale and model
How does scale change vision?
– Ljubljana: biking around the city
Where are people most active?
– Baghdad: learn/show using time, classification, weights
When and how are event density patterns change?
• Further work
– Implementation of spatio-temporal NetKDE
– Fixed time comparison (looking for concordances, differences)
Fuzzy-set map comparison
– Automated multi-scale multi-temporal geovizualisation
“Connected-windows” views and annimated-maps
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