NGA Geomatics - WGS 84

World Geodetic System 1984 (WGS 84)

The World Geodetic System 1984 (WGS 84) is a 3-dimensional coordinate reference frame for establishing latitude, longitude and heights for navigation, positioning and targeting for the DoD, IC, NATO, International Hydrographic Office and the International Civil Aviation Organization. WGS 84 represents the best global geodetic reference system for the Earth available at this time for practical applications of mapping, charting, geopositioning, and navigation. This standard includes the definition of the coordinate systems fundamental and derived constants, the ellipsoidal (normal) Earth Gravitational Model (EGM), a description of the associated World Magnetic Model (WMM), and a current list of local datum transformations. NGA and the National System for Geospatial-Intelligence (NSG) recommends clicking the following link for further specifications on WGS 84 DoD IT Standards Registry (DISR) (PKI Certs required).

Earth Gravitational Model (EGM)

This division in the Office of Geomatics at NGA is responsible for collecting, processing, and evaluating gravity data (free-air and Bouguer gravity anomalies). These data are then used to compute gravimetric quantities such as mean gravity anomalies, geoid heights, deflections of the vertical, and gravity disturbances. All of these quantities are used in World Geodetic System 1984 support, navigation systems, mapping projects, and different types of surveys.

An Earth Gravitational Model (EGM) is set of geopotential coefficients used in a spherical harmonic expansion to create a global potential surface to coincide with Mean Sea Level (MSL). This surface is called a geoid and it fluctuates above and below the reference ellipsoid surface established by WGS 84. For more information, click on a drop-down menu item above on the EGM tab.

Earth Gravitational Model 2008 (EGM2008)

The EGM84 and EGM96 are legacy products. Users are recommend to use the latest EGM from NGA, currently EGM2008. In 2020, NGA plans to release a new EGM, tentatively named EGM2020, where upon EGM2008 will become a legacy product.

The EGM2008 is provided as a set of normalized, geopotential coefficients complete to degree and order 2159, and contains additional spherical harmonic coefficients extending to degree 2190 and order 2159. Also provided is a 2.5-minute worldwide geoid height file, precomputed from the EGM2008. The coefficient and geoid height files have associated software and documents. EGM2008 was approved for official DoD use as documented in NGA STND.0036_1.0, 2014-07-08.

WHAT'S NEW
April, 2013 - EGM2008 Citation included below with Links to reference EGM2008 and the EGM2008 Erratum are given on left under Additional Information. EGM2008 Citation: The development and evaluation of the Earth Gravitational Model 2008 (EGM2008) - Nikolaos K. Pavlis, Simon A. Holmes, Steve C. Kenyon, John K. Factor; Journal of Geophysical Research: Solid Earth (1978-2012) Volume 117, Issue B4, April 2012.
May, 2009 - Global 2.5 Minute Geoid Undulation Grid available in GIS format.
February, 2009 - Middle East Geoid Undulation Grid available in GIS format.
February, 2009 - Propagated Error Estimates of EGM2008 released.
January, 2009 - Utility to convert binary files from Big Endian to Small Endian released.
January, 2009 - Gravity Anomalies & Deflections of the Vertical data released.
November, 2008 - SMALL ENDIAN versions of binary files released.
November, 2008 - Files & Products for Oceanographic Applications released.
July, 2008 - WGS 84 version of EGM2008 released. Includes grids and programs for computing geoid undulations relative to WGS 84 Ellipsoid.

Please provide comments, suggestions, and feedback to NGA Public Affairs Office (bottom right of page).

Earth Gravitational Model 1996 (EGM96)

The EGM96 is provided as a set of normalized, geopotential coefficients to degree and order 360. Also provided is a 15-minute worldwide geoid height file, precomputed from the EGM96. The coefficient and geoid height files have associated software and documents. EGM96 was approved for official DoD use as documented in NIMA TR8350.2, Third Edition, 4 July 1997.

Earth Gravitational Model 1984 (EGM84)

The EGM84 is provided as a set of normalized, geopotential coefficients to degree and order 180. Also provided is a 30-minute worldwide geoid height file, precomputed from the EGM84. The coefficient and geoid height files have associated software and documents. EGM84 was approved for official DoD use as documented in DMA TR8350.2, Second Edition, 1 September 1991.

World Magnetic Model (WMM)

The World Magnetic Model is the standard model used by the U.S. Department of Defense (DoD), the U.K. Ministry of Defence, the North Atlantic Treaty Organization (NATO) and the International Hydrographic Organization (IHO), for navigation, attitude and heading referencing systems using the geomagnetic field. It is also used widely in civilian navigation and heading systems. The model, associated software, and documentation are distributed by the National Oceanic and Atmospheric Administration (NOAA), National Centers for Environmental Information (NCEI) on behalf of NGA. The model is produced at 5-year intervals. With the current model expiring on December 31, 2019.

Datum Transformations & Conversions

Data acquired by NGA and referenced to a geodetic datum other than WGS 84 does not meet agency standards, and must therefore undergo a datum transformation to WGS 84. For assistance setting up geographic translations, acquiring grid system and datum parameters, running batch conversions, and loading MSP Geotrans please refer to the GEOTRANS menu item on the Data/Apps tab.

Definitions

A transformation, or more specifically a geodetic datum transformation, is a change in a coordinate based on to what geodetic datum a coordinate is referenced. The NGA and DoD approved geographic translator to perform geodetic datum transformations is MSP GEOTRANS.

A conversion, or more specifically a coordinate conversion, is a change in coordinate data from one reference system to another. The NGA and DoD approved geographic translator to perform coordinate conversions is MSP GEOTRANS.

MSP (Mensuration Services Program) GEOTRANS (Geographic Translator) v.3.7

MSP GEOTRANS is the NGA and DOD approved coordinate converter and datum translator. The user-friendly GUI has features including batch conversion capability, a choice of precision levels and the capability to add your own datum. MSP GEOTRANS can be downloaded to run as a stand-alone application. Available downloads are listed in the table below.

MSP GEOTRANS Documents and Links

FILE/LINK	DESCRIPTION
Supporting Documents	Zip file that includes a brief introduction, release notes, terms of use, and a user's and programmer's guide.
MSP GEOTRANS API	The complete API reference.

MSP GEOTRANS Downloads

Windows End User (Recommended For Most Users): The Windows End-User version is intended for end-users that operate on a Windows platform. It includes everything necessary to run GEOTRANS (including online help). It does not include the source code. A Windows installer makes the installation easy and it allows the user to create a shortcut to GEOTRANS that can be placed at a specified location. Windows 7 Users: Download the desired version, double click on the install.exe file, and follow on screen instructions; your computer will be re-booted after installation.

FILE/LINK	FILE SIZE	MD5 CHECKSUM	DESCRIPTION
Windows 32-bit Self-Installer	143 MB	d20336af4ab4660df1796c9786bd501c	IMPORTANT: Before downloading the 64-bit version, verify that 64-bit Java is installed on your system at: C:\Program Files\Java. If 64-bit Java is not installed, then download and install 64-bit Java before downloading MSP GEOTRANS, or instead download and install the 32-bit version of MSP GEOTRANS.
Windows 64-bit Self-Installer	143 MB	b9079223999ee6fe492be5fcd5cb3b59
Windows Self Installation	250 KB	5015708052b162ba5ca85bcb2080f3de
Linux User	138 MB	72fce4ea4de9b7ecc90964f82f3b5968	The Linux End-User version is intended for end-users that operate on a Linux platform. This version includes everything necessary to run GEOTRANS, including online help. This version does not include source code.
Linux Installation Instrucctions	55 KB	d9ccea99c4dec9e7c8bb27e2c7e42628
Windows Developer	149 MB	fd2a070fc260ee9e56ff279a071617cc	The Software Developers version is intended for software developers. This version is available for both Windows and Linux platforms, and includes everything included in the End-Users version plus all of the source code, documentation and a programmer's guide.
Windows Developer Instructions	49 KB	25c4fbe809552bb5ea68520a32e3d64f
Linux Developer	144 MB	a361fb718ba95a655d45dd93fda1ad95
Linux Developer Instructions	55 KB	d9ccea99c4dec9e7c8bb27e2c7e42628
MGRS Windows	68 KB	c7c8e24090c959b0ddc7200fb9decaa2	The Developer MGRS Only version is for software developers who only need the MGRS capability. This version is available for both Windows and Linux platforms, and includes MGRS, UTM, UPS, Transverse Mercator and Polar Stereographic modules, source code and documentation. This version does not include GEOTRANS executables.
Windows Developer Instructions	49 KB	25c4fbe809552bb5ea68520a32e3d64f
MGRS Linux	40 KB	e2895bbd409e806f6b5c0768bb86ade0
Linux Developer Instructions	55 KB	d9ccea99c4dec9e7c8bb27e2c7e42628
Windows Master	150 MB	0e0a10da3bbc71faa5baa47a7f38abe7	The Developer Master version is intended for software developers, and includes the GEOTRANS executables for all platforms, all source code and documentation. The difference between the Windows and Linux master is the zip method.
Windows Developer Instructions	49 KB	25c4fbe809552bb5ea68520a32e3d64f
Linux Master	146 MB	11ed84cba46fe8db97993ef20cf3173e
Linux Developer Instructions	55 KB	d9ccea99c4dec9e7c8bb27e2c7e42628
MSP GEOTRANS App	10.5 MB	2bb04911d5afdc343f4b530fe9809c60	The MSP GEOTRANS app is intended to be installed on Android 2.3 and later OS devices. The MSP GEOTRANS App is available through the NGA GEOINT APP Store on the SBU. A GEOINT Online account is required to access the GEOINT App Store. The MSP GEOTRANS app may also be downloaded using the link to the left.
NOTE: If the filename is different after downloading, be sure to rename the file for decompression purposes. After downloading one of the MSP GEOTRANS files, you may optionally verify that the downloaded file exactly matches the download file stored on the distribution server by generating an MD5 digest of your downloaded file. The MD5 digest value for your downloaded file must exactly match the MD5 digest published on this web page for the files to be the same.

MSP GEOTRANS Assistance

Having trouble starting GEOTRANS? Here are some suggestions
If you have installed GEOTRANS and are unable to get it to start (no message given) you may need to download the MS Visual C++ Redistributable Package. This software is normally included on a computer, but system configurations do vary. Please read the instructions for installing GEOTRANS on a Network Drive.

MS Visual C++ Redistributable Package for 32-bit user download: http://www.microsoft.com/en-us/download/details.aspx?id=5582

MS Visual C++ Redistributable Package for 64-bit user download: http://www.microsoft.com/en-us/download/details.aspx?id=14632

NOTE: Java 32-bit and 64-bit may be required to run MSP GEOTRANS. GEOTRANS 3.7 was built using Java JDK 1.8 update 72. The latest releases of Java can be found at Orcale.com. Should you encounter a Windows Error 2 condition during MSP GEOTRANS install, this error usually occurs because the wrong bit-level for Java was selected. Especially with Java 1.8, the Windows environment variable for PATH is often not set correctly. You may try the following procedure to correct the condition:

Right click on Computer and select properties.
On the left panel, click on Advanced system settings.
At the bottom of the Advanced tab, click on Environment Variables...
Under the System variables, select Path and click Edit.
Change the Variable values for C:\ProgramData\Oracle\Java\javapath to C:\Program Files (x86)\Java\<your java version>\bin
Click Ok and exit out of the Advanced tab.

Contact the MSP/GEOTRANS Help Desk
For assistance with MSP GEOTRANS software, including questions about source code, please contact the NGA Enterprise Service Center (ESC) at 800-455-0899 or email MSP_Help@nga.mil (Unclassified content only).

Earth Gravitational Model 2008 (EGM2008) Data and Apps

The following links contain documentation, source code, data, and supporting inputs and tools for EGM2008.

FILE/LINK	DESCRIPTION
EGM2008 Spherical Harmonics (104MB)	Zip archive containing all EGM2008 Spherical Harmonics code and documentation.
EGM2008 2.5 Minute Interpolation Grid (128MB)	Zip archive containing all EGM2008 2.5 Minute Interpolation Grid code and documentation.

Earth Gravitational Model 96 (EGM96) Data and Apps

The following links contain documentation, source code, data, and supporting inputs and tools for EGM96.

FILE/LINK	DESCRIPTION
360 Spherical Harmonics	Zip archive containing all EGM96 360 Spherical Harmonics code and documentation.
15 Minute Interpolation Grid	Zip archive containing all EGM96 15 Minute Interpolation Grid code and documentation.
EGM96 Geoid Calculator	Online calculator to determine EGM84 geoid height based on latitude and longitude inputs.

Earth Gravitational Model 1984 (EGM84) Data and Apps

The following links contain documentation, source code, data, and supporting inputs and tools for EGM84.

FILE/LINK	DESCRIPTION
180 Spherical Harmonics	Zip archive containing all EGM84 Spherical Harmonics code and documentation.
30 Minute Interpolation Grid	Zip archive containing all EGM84 30 Minute Interpolation Grid code and documentation.
EGM84 Geoid Calculator	Online calculator to determine EGM84 geoid height based on latitude and longitude inputs.

World Magnetic Model 2015 - Apps

Magnetic Field Calculators

World Magnetic Model 2015 - Data

The Fortran and C WMM 2015 models can be obtained from NCEI by HTTPS.

Services

Services require PKI certs and allow visualization via the IC Portal or ArcGIS desktop (download). After selecting the link below, additional viewing options may be available by following the link under the "Map Contents" heading.

SERVICE NAME	LINK	DESCRIPTION
Earth Gravity Model 2008 (EGM08)	MoW REST Endpoint	EGM08 is an interpreted grid of the spherical harmonics model of the earth's gravitational potential. The grid was formed by merging terrestrial, alimetry-derived and airborne gravity data. EGM08 is complete to degree and order 2159, and contains additional coefficients up to degree 2190 and order 2159.
World Magnetic Model 2015 (WMM)	MoW REST Endpoint	The World Magnetic Model (WMM) is a set of data, software and charts used to characterize, depict, and predict various properties of the earth's magnetic field. Primarily used for portraying declination data (magnetic north) on maps and charts. The model is produced at 5-year intervals, with the current model expiring 31 Dec 2019.

WGS 84 Resources & Links

DOCUMENT	DESCRIPTION	DOCUMENT
NGA.STND.0036_1.0.0_WGS84	NGA Standardization Document, Department of Defense, World Geodetic System 1984 (updated 8 July 2014)	WGS 84 definition and relationships with local geodetic systems.