Talk:Shuttle Radar Topography Mission

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External Links[edit]

I have expanded this article, but I have not, so far, posted an external link to Free SRTM data with voids corrected using topographic maps, although it would seem to me to be relevant and informative. The reason: that site is mine and for me to post such a link could be considered contrary to WP:EL#Links normally to be avoided (clause 3). Viewfinder 17:43, 2 August 2006 (UTC)

Does your site state the license of your improved data or are they in public domain? Bumbulski 11:47, 3 August 2006 (UTC)

The terms of use are linked to the link above, but can be accessed directly on my home page. Provided any uploaded or distributed products derived from these data mentions their source, or the distributor obtains my written permission, no fees are payable and no licence is required. Viewfinder 16:25, 3 August 2006 (UTC)

As I find Viewfinder's void-corrected SRTM data incredibly useful, and generally recommend it (rather than the official uncorrected dataset) as a good general-purpose DEM, I have added it to the main article. — ras52 12:30, 15 September 2006 (UTC)

Thank you! Viewfinder 15:36, 15 September 2006 (UTC)

Void-filled SRTM datasets[edit]

I just added this section. I know it's far from perfect, feel free to improve it. The main reason I added this is because it's hard to find the best datasets out there. After personal communication with the scientists behind the HydroSHEDS and CGIAR-CSI datasets, they confirmed with me that the algorithms used for version 3 and 4 of the CGIAR version is what is best at the moment and for the coming years. However, no scientific article is available yet since the HydroSHEDS dataset is still in the process of being released. Lordsatri 14:35, 21 August 2007 (UTC)

I think one important point is how the void filled datasets are produced: are they made by interpolation from the surrounding data, or are they by done by reference to other data sources (or a mixture)? In the case of Viewfinder's, I know it is all (almost all?) done from additional sources, but I in the case of the others, I don't know. — —The preceding unsigned comment was added by Ras52 (talkcontribs) 14:41, August 21, 2007 (UTC).
As far as I can tell from their listed sources, only SRTM and 30" sources have been used by HydroSheds, so however good their interpolation algorithms may be, they necessarily exclude mountain summits that fall within SRTM voids, and have no high resolution data north of 60 degrees of latitude. The CGIAR sources are more various, and include Viewfinder data, but for some areas, including the Alps and Karakoram, CGIAR did not get round to using Viewfinder data. In these areas the results are no improvement on pure interpolation, and there is also no polar data. Viewfinder voidfills are wholly from topos, there is no interpolation other than between contours derived from topos. Declaration of interest: I am the author of the Viewfinder data. In general, I have not created data for areas where I found existing data to be adequate, so my coverage is partial. Viewfinder 16:46, 21 August 2007 (UTC)

Original motivation for mission?[edit]

I wonder if anyone has some information to contribute about the original defense department motivation for the mission? I understood from word of mouth that the radar mapping mission coincided with a strong need for this information to allow unmanned aerial vehicles to operate safely around the world, and give the remote pilots a visualization of the terrain. It is certainly on the same timescale. Does anyone have a link to such info to add to the page? —Preceding unsigned comment added by Supernova87a (talkcontribs) 20:30, 19 January 2009 (UTC)

Aster GDEM released[edit]

Aster GDEM has now been released making it the highest resolution publically released DEM. --Firefishy (talk) 02:02, 1 July 2009 (UTC)

The ASTER data however is not actually functionally an improvement over SRTM regrettably. See http://www.gravitystorm.co.uk/shine/archives/2010/01/13/aster-not-worth-it-yet/ for example. --Speedevil (talk) 19:50, 6 June 2010 (UTC)

Void filled datasets[edit]

The CGIAR dataset is not global in that it does not cover areas north of 60 degrees N or south of 60 degrees S. Viewfinder Panoramas] has been global since December 2012. I cannot update the relevant section as I am the proprietor of the Viewfinder Panoramas site, but I would appreciate its update. Viewfinder (talk) 23:19, 13 September 2013 (UTC)

DTM or DSM?[edit]

I think the expression "digital elevation models" in the text should be qualified with a "DTM" or "DSM"; I would do the mod myself, unfortunately I don't know the answer (and will have to find it outside Wikipedia...) --AlainR345Techno-Wiki-Geek 19:11, 21 October 2013 (UTC)

Not so easy to find a direct answer... but here's what the NASA FAQ says about that to the question "Did the radar sample the tops of trees or the ground level?": The radar does not "see" through thick vegetation canopies. It probably penetrated a little way into some canopies, but in general it followed near the top of the canopy. --AlainR345Techno-Wiki-Geek 19:36, 21 October 2013 (UTC)

Yes, the SRTM C-band (5.6 cm) radar probably penetrated into vegetation to a variable extent, depending on the type of vegetation. This means that it is technically neither a DTM nor a DSM, but something in between. EricJFielding (talk) 20:02, 22 February 2014 (UTC)