do photo sharing websites represent a sufficient database to aid in national map updating or change...
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Do photo sharing websites Do photo sharing websites represent a sufficient database represent a sufficient database to aid in national map updating to aid in national map updating
or change detection?or change detection?
Vyron Antoniou, Jeremy Morley, Muki HaklayVyron Antoniou, Jeremy Morley, Muki HaklayDepartment of Civil, Environmental and Geomatic Engineering
Geotagged photos in Web 2.0
Spatially explicit
Spatially implicit
Examining geotagged photos for UK
• 1 km2 National Grid for UK
• 238,920 tiles
• Distribution of 4.4 million geotagged photos
Tile statistics:
Frequencies (tile photo population)
Spatial Distribution
FlickrPicasa WebGeograph Panoramio
Expectation Surfaces
FlickrPicasa WebGeograph Panoramio
Popular tiles (>15 photos)
FlickrGeograph
≈≈5.1 %
of the total area
3.7 %
of the total area
Data Flow in popular tiles
For both sources about 3.800 of the popular tiles had geotagged photos submitted for three consecutive semesters. This is
approximately 1.6% of the total area
six months later…..
-975
15,094
DifferencesPositive: 9.2%
Negative: 1.8%
New Tiles
8554 tiles = 3.6%
1% more than 3
…but the pattern remained the sameFlickr January 2009
…but the pattern remained the sameFlickr July 2009
©Crown Copyright/database right 2009. An Ordnance Survey/EDINA supplied service.
©Crown Copyright/database right 2009. An Ordnance Survey/EDINA supplied service.
©Crown Copyright/database right 2009. An Ordnance Survey/EDINA supplied service.
??
==oror
≠≠or or
≈≈Explicit
What is the spatial distribution of changes?
oror
Changes
Implicit
Popular
User Behaviour.
Time between capturing and uploading a photograph
Conclusions
- Two types of sources: explicit and implicit
- Implicit : Huge volumes of data, poor spatial coverage
Explicit: Moderate data volume, sufficient spatial coverage
- We need the amount of data of a spatially implicit source and the spatial coverage of a explicit source
- Spatially speaking … no Long-Tail in implicit Web 2.0 apps
- We need to understand the pattern of changes on the ground
Thank you!Thank you!