If you are interested in a service that does this, I host a redundant elevation service using NED, SRTM and ASTER data. It tries NED (highest res) first, falls

If you are interested in a service that does this, I host a redundant elevation service using NED, SRTM and ASTER data. It tries NED (highest res) first, falls back to SRTM and then finally to ASTER. ASTER is pretty bad in some areas, but it's the only dataset available above 60 degrees north/south. We use it for our route planner on http://ridewithgps.com http://ridewithgps.com Feel free to email me, cullen@ridewithgps.com if you want to use it, or just have questions about getting something together yourself. Edited to add: code is open source, you just need an afternoon to tweak it (it's a ruby lib and a sinatra app) to work, along with some SRTM gridfloat dems. Code is here: https://github.com/ridewithgps/humps https://github.com/ridewithgps/humps And if you need to convert from geotiff to gridfloat, here's some bad C: https://github.com/kingcu/geotiff2gridfloat https://github.com/kingcu/geotiff2gridfloat