Posted on November 14th, 2012

Global Multi-Resolution Topography

Our second Free For All this month highlights the Global Multi-Resolution Topography (GMRT) dataset.  This elevation dataset separates itself from others by incorporating sea floor bathymetry and is constantly updated.

Are you looking for an elevation dataset that includes sea floor bathymetry? If so, look no farther than the Global Multi-Resolution Topography (GMRT) dataset hosted by Columbia University. The GMRT is a constantly updated elevation dataset that includes both sea floor bathymetry and land topography. There are more than 3,500 bathymetric datasets that have been complied in the GMRT with resolutions down to 50-meters in some coastal areas. For terrestrial areas, there is a combination of 30-meter ASTER elevation data and 10-meter USGS NED.

There are multiple ways to access the GMRT dataset. The most simple is the online viewer which can be accessed by clicking on the map on the GMRT homepage. If you want to download a complied GRID version of the dataset, you can click on the Create Map/Grid link located on the left side of the homepage. While this is an easy to use interface, one disadvantage is that the resolution of the GRID file is dependent on the area you download – as the area grows, the resolution shrinks. There are also streaming web services you can access here.

If you are in need of the full resolution GRID files, you can access them by:

  1. Clicking on the Search for Data button.
  2. Select From List the Bathymetry option.
  3. Now click on Run Search.
  4. Finally you can narrow resolution with the Location filter.

Until my next edition of Free For All, happy hunting for free GIS data!

Brock Adam McCarty
Map Wizard
(720) 470-7988

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