Grassroots Mapping is a series of participatory mapping projects involving communities in cartographic dispute. Seeking to invert the traditional power structure of cartography, the grassroots mappers used helium balloons and kites to loft their own “community satellites” made with inexpensive digital cameras.

Initial Map Warper test with kite imagery

January 16th, 2010 by Jeffrey Warren

We’re working to process and rectify all the imagery we captured on Thursday, but here’s an initial attempt at rectifying an image. I must admit I was initially discouraged that the Google map seemed pretty decent (it’s supplied by DigitalGlobe) but now that I’m trying to actually rectify images against it, it’s really almost unusable!

I can’t see any useful detail, and almost all of the houses have moved or changed… about one in a hundred roofs match up, making it very difficult to rectify. I think we need one really good very high altitude shot to fix our overall layout, then we can rectify the lower altitude, higher detail imagery. We’ll try Tuesday afternoon.

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2 Responses to “Initial Map Warper test with kite imagery”

  1. Jeffrey Warren Says:

    Stuart Gill from the World Bank has been asking whether we can tell what buildings are made of – and we almost can from this height. Roof material can be seen, and from some of the sideways images (like this one; see more at the Flickr feed) we can definitely make out wood/brick/plastic. But I’m hoping we can run around with the kids and do a quick survey of building materials anyways.

  2. wetland Says:

    A great idea with the balloons! Im working on a project that requires georeferencing, so this post caught my eye. Grass GIS (open source GIS) has a georeferencer utility and MapAnalyst ( can calculate distortion.

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