In 1996 the NOAA GLOBE project provided terrain elevation data for the entire Earth with a horizontal grid spacing of 30 arc seconds (approximately 1 kilometer). GLOBE is usually considered a more modern, slightly more complete version of the USGS GTOPO30 project. See also the DEM, GTOPO30 topic.
GLOBE files may or may not use a .dem extension. Although GLOBE files may use the same .dem extension as GTOPO30 .dem files, the format is different from both USGS DEM files and GTOPO30 DEM files. Manifold can normally autodetect which type of DEM is being imported. The example below uses GLOBE files without a three-letter extension, as downloaded from the NOAA site at http://www.ngdc.noaa.gov/mgg/topo/gltiles.html
To import from GLOBE format:
Choose File-Import from the main menu.
In the Import dialog browse to the folder containing data of interest.
Choose . Files (GLOBE) (".") as the file type.
Double-click the file for the data of interest.
A table and an image will be created.
The image shows the terrain elevation data. We can double-click on the image to view it.
For a more interesting display, we first create a new data source using a Bing street maps imageserver as shown in the Example: An Imageserver Tutorial topic. We then create a map and drag and drop the Bing layer into the map, and then we drag and drop the g10g image into the map.
We use the Style pane to color the image and to apply hill shading, as seen above.
The result is a much more interesting and understandable display, seen somewhat zoomed in.
The illustrations above show a layer that has been added to the map, called Caspian.
Both the GLOBE data set and the highly similar GTOPO30 data set do not use transparent pixels in the region covered by the Caspian Sea, and instead fill level terrain surface. To provide a more understandable display we have downloaded a shapefile for the area of the Caspian Sea from the web and have added it above, using the same light blue color as Bing uses for ocean areas. In general, neither GTOPO30 nor GLOBE "cut out" areas of major lakes, so lakes such as the Great Lakes and other inland seas should be added with other layers.
Legacy - GLOBE files are fairly rare, with few sites providing downloads. Downloads for NOAA GLOBE are currently at http://www.ngdc.noaa.gov/mgg/topo/gltiles.html Manifold can easily handle GLOBE data for the entire Earth if merged into a single image using the Edit - Merge - Merge Images command.
File names - When downloaded from the http://www.ngdc.noaa.gov/mgg/topo/gltiles.html site, NOAA uses the following naming scheme for the files for each tile. The "G" tile is the g10g file imported in the example above.
Example: Spectacular Images and Data from Web Servers