# DTED -- Military Elevation Data

GDAL supports DTED Levels 0, 1, and 2 elevation data for read access. Elevation data is returned as 16 bit signed integer. Appropriate projection and georeferencing information is also returned. A variety of header fields are returned dataset level metadata.

## Read Issues

### Georeferencing Issues

The DTED specification (MIL-PRF-89020B) states that horizontal datum shall be the World Geodetic System (WGS 84). However, there are still people using old data files georeferenced in WGS 72. A header field indicates the horizontal datum code, so we can detect and handle this situation.

- If the horizontal datum specified in the DTED file is WGS84, the DTED driver will report WGS 84 as SRS.
- If the horizontal datum specified in the DTED file is WGS72, the DTED driver will report WGS 72 as SRS and issue a warning.
- If the horizontal datum specified in the DTED file is neither WGS84 nor WGS72, the DTED driver will report WGS 84 as SRS and issue a warning.

### Checksum Issues

The default behaviour of the DTED driver is to ignore the checksum while reading data from the files. However, you may specify the environment variable DTED_VERIFY_CHECKSUM=YES if you want the checksums to be verified. In some cases, the checksum written in the DTED file is wrong (the data producer did a wrong job). This will be reported as a warning. If the checksum written in the DTED file and the checksum computed from the data do not match, an error will be issued.

## Creation Issues

The DTED driver does support creating new files, but the input data must be exactly formatted as a Level 0, 1 or 2 cell. That is the size, and bounds must be appropriate for a cell.

## See Also:

- Implemented as `gdal/frmts/dted/dteddataset.cpp`.