On Friday 20 November 2009 07:09:35 Barry Rowlingson wrote: > 2009/11/20 Yong Li <[email protected]>: > > Dear all folks, > > > > I was informed in the 6th Digital Earth Conference that there is a better > > place to acquire high resolution of global DEM developed by ASTER, called > > GDEM with 30 m resolution, and fantastically free of charge. I tried some > > here (http://www.gdem.aster.ersdac.or.jp/) and it is really better than > > SRTM if you are outside USA. Hope you will enjoy the free meal. > > I just had a look at the tiles near me, and there's quite a bit of > noise and obvious artefacts - unless there really is a 2000m tower > about 180m across that I've not noticed in the middle of the > countryside! > > I've not compared with SRTM yet... > > Barry >
I looked at some here around the North American Great Lakes, and I have to say I would be very leery about using it in low relief areas. Visually it looked a lot nicer in the California coastal range, so perhaps less vegetation and higher relief is important for the sensor. That said, it's terrific that alternative global medium-resolution DEMs are becoming available. Also, I think this ASTER-derived product has captured higher latitude locations than SRTM (which gets to about 60N and 60S), so it may be not simply the best but the only choice for many regions. Ashton -- Ashton Shortridge Associate Professor [email protected] Dept of Geography http://www.msu.edu/~ashton 235 Geography Building ph (517) 432-3561 Michigan State University fx (517) 432-1671 _______________________________________________ R-sig-Geo mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-geo
