[Openstreetmap] Legal viability of using Landsat and SRTM data as basemaps

[Andrew Birkett]

On Wed, 2005-04-20 at 19:43 +0100, Nick Whitelegg wrote:
> I use SRTM data on my Freemap site: http://www.free-map.org.uk. The contours 
> seem to be pretty accurate to me in terms of correct horizontal positioning 
> of hills and valleys. From a vertical point of view, they get confused by 
> tree cover so tree-covered hills are perhaps 20-50ft higher than they should 
> be.

This also obviously affects cities, due to high-rise buildings.  Perhaps
a filter which takes the local minimum around a point will be useful in
this case.  I think the Flightgear project used SRTM data for making
terrain, and they found that the original unfiltered SRTM data for San
Francisco was an amusingly spiky mixture of high and low datapoints.

Andrew
--
- http://www.nobugs.org/ -