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USGS has been moving towards serving data through The National Map Viewer. They have several WMServices through their website that serve elevation data to the public (hillshade & DEM). The problem is that geoprocessing tools in ArcToolbox won't accept these layers as inputs.

Where can I download (free) DEM gis data that I can use in analysis? I'm specifically interested in the 1/3 arc second (~10m) or the 1 arc second (~30m) data.

Currently I'm going through the USGS NED Tile download tool, which has ~4 files per county. My areas of interest cover about 50 counties -- I don't see myself manually downloading these files one by one.

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4 Answers 4

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You can download NED data for entire counties and also entire states (though I've never needed an entire state) using the National Map Viewer, click the "Download Data" button in the upper-right, then choose Counties or States as your reference area, click the county/state you're interested in, and a list of (usually just one) search result pops up on the left. Click the "Download" link (lower-left of the search result text) and you'll see a list of available data sets, just check "Elevation", choose your format, and click "Next". The site will email you a link, since all the county and state NED data is pre-packaged into zip files you should get a download link pretty quickly.

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Thanks - I missed that link in the top corner, and the elevation data wasn't in the TOC. These viewers are nice in that they give geographic context to public datasets, but way too often they're totally overloaded and bogged down. This thing is crawwwwling along. –  Roy Jun 21 '12 at 18:35
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Another USGS site is seamless.usgs.gov, been using that for years now. In the Download tab, select the NED version you want, then draw your area to download using the tool from the Downloads toolbar on the left. There are other methods of extracting areas as well in that toolbar. You can get GeoTiff or binary grids.

Another option is bulk download, where you send the USGS a hard drive and they put the data on it for you. You pay for shipping both ways.

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Another tip on the seamless extractor, when you get your Request Summary, you can change not only the data format, but also the maximum size per piece of the download. It defaults to 100MB, but you can up to 250, which can keep you from getting multiple tiles, or as many tiles.

enter image description here

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Is there any website from which I can download at least a few GB of DEM data at once? –  Nav Aug 31 '12 at 3:36
    
@Nav Not that I'm aware of. –  Chad Cooper Aug 31 '12 at 12:35
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Another place to look is the NRCS Geospatial Data Gateway. They allow you to pick by state and county and then download data for free. They had 10m and 30m DEM data the last time I checked, plus a lot of other data too. And, personally, I think their website is easier to navigate than the USGS.

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I use the data gateway all the time, I even checked for DEMs but I don't think they're serving elevation data at this point. –  Roy Jun 22 '12 at 2:37
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It must depend on the state/county you are looking at. For Utah, they have the entire state covered for 10m and 30m DEMs. Is the area/state you are looking at particularly flat and of little relief? Some states are better than others in terms of data coverage. –  Baltok Jun 22 '12 at 13:52
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The USGS Global Data Explorer has version 2 of the 30 m ASTER Global DEM—apparently it's an improvement over version 1, but in my opinion it's still pretty crummy. They also have the 30 m and 90 m Shuttle Radar Topography Mission DEM and the 1 km GTOPO30 DEM.

A better source for the (90 m) SRTM DEM is CGIAR's website. Their team has processed the raw 90 m SRTM data to fill holes and so-on. It is currently up to version 4; thus the CGIAR site is a better source for 90 m SRTM (USGS don't explicitly say what version they are serving).

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