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The plane and crew

The 2009 AGI conference was held in the town in September 2009. Prior to the conference aerial photography of the town was flown using a small plane chartered with funding from ITO World and Traveline. The photographer on board, OSM contributor JR Peterson, used a normal digital camera to take the photos whilst sat in the cockpit. This was as much a demonstration of what is possible than a serious attempt to cover an area.


  • Hundreds of photos were taken
  • The best ones were warped against existing OSM maps using by various people
  • The geotiffs were downloaded for processing by Gravitystorm
  • gdalwarp used to project into spherical mercator
  • mapnik and used to read warped geotiffs, composite them, and output .png files
  • the end tiles then hosted on the dev server

Using the imagery

The end result, shown as a background to Potlatch

Warning: This imagery layer is of "experimental" quality. Use GPS traces for road alignments.

In Potlatch, add the following url to your custom imagery source:!/!/!.png

In Josm, use the slippy map plugin. Can anyone expand the instructions to use the url above?

Things we learned

  • The most important thing is how straight-down the photos are. We don't need them to professional quality (i.e. gyro-stabilised, 90°) but anything below about 70° to the vertical isn't that useful. 45° pictures make nice panoramas but aren't good for warping.
  • It appears therefore you need the plane to be on a reasonable banked turn to get good shots off.
  • Warping becomes chicken-and-egg when you use OSM data as a reference, and then try using the imagery as a reference for changing the data. It really helps to have GPS traces of main roads to keep things under control
  • reprojecting the tiffs into spherical mercator isn't great, since it's a second warping. It would be great to use the original image + control points and go straight to the end projection.

Other Links

Feel free to contact Gravitystorm if you have imagery of other places that you need processed.