DTED (Digital Terrain Elevation Data)

Description

The DTED format was developed for the distribution of gridded elevation data that was assembled by the US Defense Mapping Agency (DMA). The DMA later changed it's name to National Imagery and Mapping Agency (NIMA) but is now called the National Geospatial Intelligence Agency (NGA). DTED data is available at three different resolutions, which are referred to as Level 0, Level 1 and Level 2. Each DTED file contains elevation data for a 1 degree latitude by 1 degree longitude cell. Latitudes are divided into a total of 5 zones, and the x-size of pixels differs for each zone, getting larger toward the poles.

Grid Information

Coord. System: Geographic decimal degrees, fixed-angle
Cell Size (Level 0):
(arcseconds)
  Zone 1 Zone 2 Zone 3 Zone 4 Zone 5
X-size: 30 60 90 120 180
Y-size: 30 30 30 30 30
Cell Size (Level 1):
(arcseconds)
  Zone 1 Zone 2 Zone 3 Zone 4 Zone 5
X-size: 3 6 9 12 18
Y-size: 3 3 3 3 3
Cell Size (Level 2):
(arcseconds)
  Zone 1 Zone 2 Zone 3 Zone 4 Zone 5
X-size: 1 2 3 4 6
Y-size: 1 1 1 1 1
Tile Size (Level 0):
  Zone 1 Zone 2 Zone 3 Zone 4 Zone 5
Columns: 121 61 41 31 21
Rows: 121 121 121 121 121
Tile Size (Level 1):
  Zone 1 Zone 2 Zone 3 Zone 4 Zone 5
Columns: 1201 601 401 301 201
Rows: 1201 1201 1201 1201 1201
Tile Size (Level 2):
  Zone 1 Zone 2 Zone 3 Zone 4 Zone 5
Columns: 3601 1801 1201 901 601
Rows: 3601 3601 3601 3601 3601
Tile Span: 1 degree longitude x 1 degree latitude (all Levels)
Data Type: 2-byte integer, signed, MSB (Most Significant Byte first)
Horizontal Datum: WGS 84 or WGS 72 (older)
Vertical Datum: Earth Gravitational Model 1996 (EGM96) geoid
Vertical Units: meters
Nodata Value: -32767
Formats: DTED format, with filename extensions ".dt0", ".dt1" and ".dt2".

Latitude Ranges for Zones:
Zone 1 = [-50, 50];
Zone 2 = [-70,-50] and [50,70];
Zone 3 = [-75,-70] and [70,75];
Zone 4 = [-80,-75] and [75,80];
Zone 5 = [-90,-80] and [80,90].

How to Import

Choose Import DEM → DTED Level 0, 1 or 2 from the File menu and then select the file, which will usually have the filename extension ".dt0", ".dt1" or ".dt2".

Data Source

National Geospatial Intelligence Agency (NGA) of the U.S. Department of Defense

Data Availability

Level 0 data is available for most of the world. Level 1 data is available for the US and is distributed in a different format by the USGS. NGA will acquire new Level 2 data as a result of the Shuttle Radar Topography Mission (SRTM).

Web Sites

Download DEMs: http://geoengine.nga.mil/geospatial/SW_TOOLS/NIMAMUSE/webinter/rast_roam.html

NGA Home: http://www1.nga.mil

DTED Wikipedia Page: http://en.wikipedia.org/wiki/DTED

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