DTED
Encyclopedia
DTED is a standard of digital datasets which consists of a matrix of terrain elevation values. This standard was originally developed in the 1970s to support aircraft
radar
simulation and prediction.
DTED supports many applications, including line-of-sight
analyses, terrain profiling, 3-D terrain visualization
, mission planning/rehearsal, and modeling and simulation
. DTED is a standard National Geospatial-Intelligence Agency
(NGA) product that provides medium resolution, quantitative data in a digital
format for military system applications that require terrain elevation.
The DTED format for level 0, 1 and 2 is described in U.S. Military Specification Digital Terrain Elevation Data (DTED) MIL-PRF-89020B, and amongst other parameters describes the resolution for each level:
The precise spacing is defined by dividing the world into zones based on latitude, and is given in the following tables:
In addition three more levels (3, 4 and 5) at increasing resolution have been proposed, but not yet standardized.
DTED data is stored in a big endian
format where negative numbers are signed magnitude
.
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
simulation and prediction.
DTED supports many applications, including line-of-sight
Line of sight (gaming)
Line of sight, sometimes written line-of-sight or abbreviated to LoS, is a term used in wargames and some role-playing games . It refers to visibility on the playing field. Many abilities can only be used against an enemy within line of sight.In some games, miniature figures are used to determine...
analyses, terrain profiling, 3-D terrain visualization
Scientific visualization
Scientific visualization is an interdisciplinary branch of science according to Friendly "primarily concerned with the visualization of three-dimensional phenomena , where the emphasis is on realistic renderings of volumes, surfaces, illumination sources, and so forth, perhaps...
, mission planning/rehearsal, and modeling and simulation
Simulation
Simulation is the imitation of some real thing available, state of affairs, or process. The act of simulating something generally entails representing certain key characteristics or behaviours of a selected physical or abstract system....
. DTED is a standard National Geospatial-Intelligence Agency
National Geospatial-Intelligence Agency
The National Geospatial-Intelligence Agency is an agency of the federal government of the United States with the primary mission of collecting, analyzing and distributing geospatial intelligence in support of national security. NGA was formerly known as the National Imagery and Mapping Agency ...
(NGA) product that provides medium resolution, quantitative data in a digital
Digital
A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...
format for military system applications that require terrain elevation.
The DTED format for level 0, 1 and 2 is described in U.S. Military Specification Digital Terrain Elevation Data (DTED) MIL-PRF-89020B, and amongst other parameters describes the resolution for each level:
- Level 0 has a post spacing of ca. 900 meters.
- Level 1 has a post spacing of ca. 90 meters.
- Level 2 has a post spacing of ca. 30 meters.
The precise spacing is defined by dividing the world into zones based on latitude, and is given in the following tables:
| Zone | latitude |
|---|---|
| I | 0°–50° (North–South) |
| II | 50°–70° (North–South) |
| III | 70°–75° (North–South) |
| IV | 75°–80° (North–South) |
| V | 80°–90° (North–South) |
| level 0 (arc secs) | level 1 (arc secs) | level 2 (arc secs) | |
|---|---|---|---|
| latitude spacing | 30 | 3 | 1 |
| zone I longitude spacing | 30 | 3 | 1 |
| zone II longitude spacing | 60 | 6 | 2 |
| zone III longitude spacing | 90 | 9 | 3 |
| zone IV longitude spacing | 120 | 12 | 4 |
| zone V longitude spacing | 180 | 18 | 6 |
In addition three more levels (3, 4 and 5) at increasing resolution have been proposed, but not yet standardized.
DTED data is stored in a big endian
Endianness
In computing, the term endian or endianness refers to the ordering of individually addressable sub-components within the representation of a larger data item as stored in external memory . Each sub-component in the representation has a unique degree of significance, like the place value of digits...
format where negative numbers are signed magnitude
Signed number representations
In computing, signed number representations are required to encode negative numbers in binary number systems.In mathematics, negative numbers in any base are represented by prefixing them with a − sign. However, in computer hardware, numbers are represented in binary only without extra...
.