GLOBE DEM Data .?10g File Description

Didger can import GLOBE DEM data ?10g files only. GLOBE DEM data ?10s files are not supported.

GLOBE DEM data ?10g files are the Global Land One-Kilometer Base Elevation (GLOBE) digital elevation model (DEM).

This is 16-bit signed integer data in a simple binary raster. There are no header or trailer bytes embedded in the image. The data are stored in row major order (all the data for row 1, followed by all the data for row 2, etc.). All files have 10800 columns, and either 4800 or 6000 rows."

GLOBE is a data base, a data management philosophy, a working environment, and a file format. GLOBE began with the conceptual opening of a two-dimensional thirty-arc-second (30") latitude-longitude digital data array, and the hope to populate it with both the Best Available Data (B.A.D.), and the Globally Only Open-Access Data (G.O.O.D.). The former could include copyright data that might be made available for distribution by GLOBE with minimal restrictions, while the latter could not contain any restricted data. Allowing for both options has enabled GLOBE, for example, to work with the Australian Surveying and Land Information Group to develop a DEM much better than could otherwise be included while respecting the intellectual property rights of the Australian government.

Digital Elevation Data File Format

Files ?10G and ?10B ("?" is the wildcard notation for tile letters "A" through "P") are provided as 16-bit signed integer data in a simple binary raster. There are no header or trailer bytes embedded in the image. The data are stored in row major order (all the data for row 1, followed by all the data for row 2, etc.). All files have 10800 columns, and either 4800 or 6000 rows. The following diagram depicts the organization of the files:


bytes1/2.................................bytes21599/21600
       bytes21601/21602.........................bytes43199/43200
       .........................................................  
       .........................................................  
       etc.
       ................................(last byte-1)/(last byte)

The data are in little-endian byte order (that is, for IBM-compatible PCs, Digital Equipment VAXes, etc.) UNIX workstations using big-endian byte order can swap bytes using the command:



dd if=inputfilename of=outputfilename conv=swab

where "inputfilename" and "outputfilename" are replaced with the user’s selection of input and output file names

Projection Information

Listed below is the projection information for each data file in GLOBE.


Projection       Geographic (latitude/longitude)
        Datum            WGS84
        Zunits           Meters above mean sea level
        Hunits           30 arc-seconds of latitude and longitude
        Spheroid         WGS84
        Xshift           0.0000000000
        Yshift           0.0000000000
        Cell Referencing Each cell is nominally bound by 30" intervals
                         of latitude and longitude, beginning with any
                         whole degree (e.g. 0.0000 degrees)
        Parameters       NONE other than those above

Import Options Dialog

No import options dialog is displayed.

Export Options Dialog

Didger does not support GLOBE DEM data export.