Hi all,I tried download piece of the CGIAR SRTM 3s v41 and it is clear that this data is based on the Version 2 from the so called ftp (JPL or NASA or USGS) site. It was ftp://e0srp01u.ecs.nasa.gov/srtm/ and now it is http://dds.cr.usgs.gov/srtm/The Version 2 is considered as superior, but contains also one negative phenomenon, the grid above latitude N50 and under latitude S50 is little bit blurred. This phenomenon is without change also in the CGIAR data, so who wishes the best available SRTM 3s for given locality in the latitudes above 50, should use the "ftp" (now http) research grade version 1 or the SRTM 3s data from the seamless server at http://seamless.usgs.gov/CheersVlada

It will also need several terabytes of storage to do this thing globally on raw data. Ouch.So how will one person be able to download everything? Should we mount a collaborative downloadeffort?

I'll be glad to coordinate something like this.-- Karl --

I'll be glad to coordinate something like this.-- Karl --

We'd have to form some kind of study group to do this under the terms set forth by the terms of use.The source data can only be shared within the group. I believe ASTER data has been made public fordisaster research. So we will research the aversion of air disasters by training in a simulator ;)I've got Iceland, New Zealand, the British Isles, Madagascar and Tasmania so far. Will soon reviewthe completeness and quality of the data and create some tools to automate the processing.Of interest to me is a comparison with SRTM data.In theory, by averaging SRTM V4 and ASTER one should be able to reduce the mean error (RMS)a bit. We should see 3dB of gain in signal to noise ratio by averaging two independent data sources.My background is communications engineering and software engineering. I also know to programgraphics chips to do some signal processing grunt work.Christian

Hi all,I tried download piece of the CGIAR SRTM 3s v41 and it is clear that this data is based on the Version 2 from the so called ftp (JPL or NASA or USGS) site. It was ftp://e0srp01u.ecs.nasa.gov/srtm/ and now it is http://dds.cr.usgs.gov/srtm/The Version 2 is considered as superior, but contains also one negative phenomenon, the grid above latitude N50 and under latitude S50 is little bit blurred. This phenomenon is without change also in the CGIAR data, so who wishes the best available SRTM 3s for given locality in the latitudes above 50, should use the "ftp" (now http) research grade version 1 or the SRTM 3s data from the seamless server at http://seamless.usgs.gov/CheersVlada

Hi all,the mentionet blur in the v2 version of STRM 3s above latitude N50 and under the latitude S50 is just history. The new data is recalculated from full resolution source into new version v2.1, which is o.k. from this point of view and is available at http://dds.cr.usgs.gov/srtm/version2_1/SRTM3 .The version v2 is still there in the subdirectory Old. So for now the version v21 is superior official version of SRTM 3s.CheersVlada