3. GPS
● Historical source of data
● Especially useful in rural areas
● Allow WMS layer rectification
● The more we get tracks, the more the map will
be accurate.
4. Aerial imagery
● Easy tracing of linear and area features
● Imagery currently used :
● Yahoo (big cities)
● Landsat
● Special cases : Haiti, Gaza, Kyrgyzstan, Pakistan...
5. Imports
● PGS coastlines
● CIA World Databank boundaries
● AND donated data in the Netherlands
● TIGER data in the USA
● etc
6. Other maps
● Compliant license needed (PD)
● Example : CIA maps
→ Perry-Castañeda Library Map Collection
http://www.lib.utexas.edu/maps/
7. Local knowledge
● Most valuable source of data
● accurate
● up-to-date
● many details (street names, POIs...)
● But also most difficult to find
● contributions mainly in Europe and urban areas
● areas without data are often where technology is
the less spread
17. Walking Papers
● Take notes on existing map
● Automatic orthorectification
● Edition on top of the annotated map
→ Everyone can participate
→ http://walking-papers.org/