GOM - the Global Overlay Mapping System

Layer Notes - Relief Map

Relief-map ScaleThe images used for the relief map overlays were generated using the world-coverage GTOPO30 dataset, and the 3DEM software package. For more information, see the Software Used or Datasets Used pages. A set of 145 image tiles were generated, each 20° x 20°. (If you are wondering why the number is not 9x18=162, the answer is that 17 of the areas contain no land.) The tiles were joined together to make seamless continental images, and then re-sized and cropped to fit the map overlays.

Note: For those interested, the tiles will soon be available for free download on the MapAbility.Com website.

This latest version of the Global Overlay Mapper has Bathymetry, or in other words, ocean-depths, added. This was created using the GMT software package, from the ETOPO2 - 2 minute Worldwide Bathymetry/Topography dataset, and merged with the tiles described above.

The colors chosen were designed to give a clear idea of elevation changes without appearing excessively false. A key to the colors used, and the elevation values that they represent, can be seen on the right.