Technical Notes for Terrain Data Formats

MUSE Raster

The MUSE Raster file format is deprecated for STK 12.8.

The MUSE Raster file format is produced by the MUSE tools available from the National Geospatial-Intelligence Agency (NGA), formerly known as the National Imagery and Mapping Agency (NIMA). This was the first format supported by STK and has probably been obsoleted by the addition of standard formats. Additional information regarding this file format is outlined in the following table.

STK limitations	none identified
Standard Documents	Vertical datum - MSL_EGM96 (Mean Seal Level, Earth Geopotential Model of 1996)
Filename Format	.dte

USGS Digital Elevation Model

The USGS Digital Elevation Model is the standard set forth by the US Geological Survey (USGS) for handling digital elevation data for the US and Puerto Rico. Additional information regarding this file format is outlined in the following table.

STK limitations	It is restricted to files with a Geographic ground planimetric reference system. These are the 30-minute, 1-degree, and Alaska DEMs.
Relevant standard document(s)	Search for "Standards for Digital Elevation Models" on the U.S. Geological Survey website.
Vertical Datum	NGVD29 (CONUS & Alaska), Local MSL (Hawaii & Puerto Rico)
Horizontal Datum	NAD27, NAD83, WGS72, WGS84 (depends on file)
Filename Format	.dem

NIMA/NGA Mean Elevation Data

The National Geospatial-Intelligence Agency (NGA) Mean Elevation Data Terrain Directory format supports DTED, Level 1 and DTED, Level 2 CDROMs by reading the directory file, "dmed" contained therein. The directory file specifies the minimum bounding rectangle covered by the data, though the data may actually be a subset of that area. Additional information regarding this file format is outlined in the following table.

STK limitations	none identified
Relevant standard document(s)	MIL-PRF-89020A
Vertical Datum	MSL
Horizontal Datum	WGS84
Filename Format	.dmed

NIMA/NGA Terrain Cell

The National Geospatial-Intelligence Agency (NGA) Terrain Cell files are the individual cells available on DTED CDROMs.

Starting with the STK 7 release, STK supports the use of individual terrain cell files. Previous releases of STK required that you set an environment variable in order to use these files.

Additional information regarding this file format is outlined in the following table.

STK limitations	none identified
Relevant standard document(s)	MIL-PRF-89020A
Vertical Datum	MSL
Horizontal Datum	WGS84
Filename Format	.dt[0-5]

STK World Terrain

STK World Terrain uses the GTOPO30 dataset from the US Geological Survey (USGS), repackaged for improved access performance. Additional information regarding this file format is outlined in the following table.

STK limitations	none
Relevant standard document(s)	Search for GTOPO30 on www.usgs.gov.
Vertical Datum	MSL_EGM96
Horizontal Datum	WGS84
Filename Format	.hdr

MOLA

The Mars Orbiter Laser Altimeter (MOLA) terrain, distributed in PDS format, is produced from binned data from the MOLA on the Mars Global Surveyor Spacecraft by the Planetary Data Systems Geosciences Node at Washington University, St. Louis, Missouri. STK can read the PDS gridded radius map data in image format. The Martian surface can be described via topography data specified relative to the Martian areoid, also available in image format, or by radius data. You should only use the radius information in STK, since the areoid vertical datum is not supported. Additional information regarding this file format is outlined in the following table.

STK limitations	Only files containing radius data should be used since the aeroid vertical datum is not currently supported.
Relevant standard document(s)	See MOLA MEGDRs.
Vertical Datum	Sphere of radius 3396.0 km
Horizontal Datum	Sphere of radius 3396.0 km
Filename Format	.lbl (label file), .img (topography file)

For more information on the PDS format, see Support of PDS Topographic Information in STK Products.

The use of topography data for bodies other than the Earth may require modifications to the reference shape of the body for accurate determination of the body surface. For more information, see Using Topography Data for Central Bodies Other than the Earth.

If you use terrain data for the Moon from the Clementine mission (https://pds-geosciences.wustl.edu/missions/clementine/gravtopo.html), which models the Moon as an oblate spheroid, you must uncomment the following parameters in the Moon.cb file:

Shape OblateSpheroid
MajorAxis 1738000.0
MiddleAxis 1738000.0
MinorAxis 1737400.0

You must also comment out using # the following parameters that model the Moon as a sphere from the Moon.cb file:

Shape        Sphere
MajorAxis    1737400.0
MiddleAxis   1737400.0
MinorAxis    1737400.0
RefDistance 1737400.0
MinRadius    1737400.0

The Moon.cb file is located in the <STK install folder>\STKData\CentralBodies\Moon folder.