## NAME

m.dted.extract - Extracts digital terrain elevation data (DTED - levels 1 and 2) produced and supplied by the Defense Mapping Agency (DMA) on 1/2-inch magnetic tapes.
(GRASS Data Import/Processing Program)

## SYNOPSIS

m.dted.extract if=name of=name hf=name n="string" s="string" e="string" w="string"

## DESCRIPTION

m.dted.extract extracts DTED (Levels 1 and 2) digital terrain elevation data produced by the Defense Mapping Agency (DMA) from 1/2-inch magnetic tapes obtained from DMA.

## OPTIONS

Data is read from the input file (if). If the user does not specify any input file name on the command line, the program assumes that input is coming from `/dev/rmt0`. The extracted data is placed in the output file (of). This program should be used in conjunction with the programs m.rot90 and r.in.ll to convert DTED data to GRASS raster format.

### Parameters:

input=name
  The pathname of the tape device where the raw DTED data exists (default is `/dev/rmt0`)
output=name
  The full pathname of the output file into which the extracted tape data is to be copied
header=name
  The full pathname of a file to contain descriptive information about the extracted data; should be placed in the same directory as the output file
north="string"
  North latitude value defining the boundaries of the extraction geographic region (format: dd.mm.ss[n|s])
south="string"
  South latitude value defining the extraction geographic region (format: dd.mm.ss[n|s])
east="string"
  East longitude value defining the extraction geographic region (format: dd.mm.ss[e|w])
west="string"
  West longitude value defining the extraction geographic region (format: dd.mm.ss[e|w])

The north, south, east and west parameters define a geographic region that should completely encompass the data set. dd.mm.ss are degree, minute, and second values. Only data that falls within this defined geographic region will be extracted from the tape.

## EXAMPLE

The command line:

  m.dted.extract in=/dev/rmt0 out=dted.out head=dted.head n=37.30.00n s=37.15.00n e=103.30.00w w=103.45.00w

will extract DTED data from `/dev/rmt0`, store it in a file named `dted.out`, and store some supporting information in the file `dted.head`. Only data that falls within the geographic region defined by the coordinates north, south, east and west will be extracted.

## NOTE

The user should examine the contents of the header file produced by this program; it contains information needed as inputs to the data rotation and raster file import programs m.rot90 and r.in.ll, respectfully.

## BUGS

The format of the header file for DTED Level 1 and 2 data was changed in 1987. m.dted.extract and m.dted.examine only operate on DTED data containing pre-1987 headers. DTED data containing the pre-1987 headers may be purchased from the DMA upon request.

## DIAGNOSTICS

Invalid requests are so designated.

## SEE ALSO

Pursuance of Elevation Data, by Stuart Bradshaw, USACERL
DTED and DEM Elevation Data Extraction, by Stuart Bradshaw, Mary Martin, and Chester Kos, USACERL

g.region
m.dmaUSGSread
m.dted.examine
m.examine.tape
m.region.ll
m.rot90
r.describe
r.in.ll
r.rescale
r.slope.aspect

## AUTHOR

Michael Shapiro, U.S.Army Construction Engineering Research Laboratory

Last changed: $Date: 2002/02/28 12:47:25 $