NGS Products & Services NGS Geodetic Tool Kit Program Descriptions NGS homepage NOAA homepage
on-line interactive computation of geodetic values

See the text version of an article about the NGS Geodetic Toolkit that appeared in the Professional Surveyor magazine, May 2003 Volume 23, Number 4

DEFLEC99
Computes deflections of the vertical at the surface of the Earth for the conterminous United States, Alaska, Puerto Rico, Virgin Islands, and Hawaii.

PC software is available for download.

DEFLEC09
Computes deflections of the vertical at the surface of the Earth for the conterminous United States, Alaska, Guam and Northern Mariana Islands and American Samoa.

PC software is available for download.

DEFLEC12A
Computes deflections of the vertical at the surface of the Earth for the conterminous United States, Alaska, Puerto Rico, Guam and Northern Mariana Islands and American Samoa.

PC software is available for download.

See the text version of an article about NGS GEOID Tools that appeared in the Professional Surveyor magazine, December 2003 Volume 23, Number 12

DYNAMIC_HT
Computes a dynamic height based on the NAVD88 orthometric height and gravity value.


GEOCON
The National Geodetic Survey has released the GEOCON set of tools for performing three-dimensional coordinate transformations.


GEOCON11
The National Geodetic Survey has released the GEOCON11 set of tools for performing three-dimensional coordinate transformations.

G99SSS
Computes gravimetric, geocentric geoid undulations relative to the ITRF97/GRS-80 reference ellipsoid in the conterminous United States. Primarily for scientific use.

PC software is available for download.

See the text version of an article about NGS GEOID Tools that appeared in the Professional Surveyor magazine, December 2003 Volume 23, Number 12

GEOID99
Computes hybrid geoid undulations, and used to convert between NAD 83 GPS derived ellipsoid heights and NAVD 88 Helmert orthometric heights. Areas covered are the conterminous United States, Hawaii, Alaska and Puerto Rico and the American Virgin Islands.

PC software is available for download.

See the text version of an article about NGS GEOID Tools that appeared in the Professional Surveyor magazine, December 2003 Volume 23, Number 12

GEOID03
GEOID03 is an update of the GEOID99 model. GEOID03 covers the coterminous U.S., Alaska, Hawaii, Puerto Rico and the U.S. Virgin Islands.

PC software is available for download.

GEOID06
GEOID06 is an update of the GEOID99 model. GEOID06 currently covers only the state of Alaska.

PC software is available for download.

GEOID09
GEOID09 is an update of the GEOID03 hybrid model.

PC software is available for download.

GEOID12 (Replaced by GEOID12A)
GEOID12 is an update of the GEOID09 hybrid model.

PC software is available for download.

GEOID12A
GEOID12A is a replacement of the GEOID12 hybrid model.

PC software is available for download.

USGG2003
USGG2003 is an update of the G99SSS model. USGG2003 covers only the coterminous U.S.

PC software is available for download.

USGG2009
USGG2009 is a gravimetric geoid model and an update of the USGG2003 model.

PC software is available for download.

USGG2012
USGG2012 is a gravimetric geoid model and an update of the USGG2009 model.

PC software is available for download.

HTDP
The Horizontal Time-Dependent Positioning (HTDP) program allows users to predict displacements and/or velocities at locations where National Spatial Reference System (NSRS) products and services are defined. The program can also be used to transform coordinates and velocities between several different reference frames, and to update certain geodetic observations from one reference frame and/or date to another. An on-line interactive version is also available from the Geodetic Tool Kit.

PC software is available for download.

IGLD85
IGLD85 is a datum transformation tool that converts NAVD 88 Helmert heights to International Great Lakes Datum (IGLD) dynamic heights and vice-versa.


Inverse/Forward/Invers3D/Forwrd3D
INVERSE is the tool for computing the geodetic azimuth and ellipsoidal distance between two points given their latitudes and longitudes. FORWARD is the tool for computing the geodetic position of a point given the geodetic position of a beginning point and the geodetic azimuth and ellipsoidal distance between the two points. INVERS3D and FORWRD3D are 3-dimensional versions of the above programs.

PC software is available for download.

Leveling Online Computations User Service (LOCUS)
The Leveling Online Computations User Service (LOCUS) is a Web utility developed by the National Geodetic Survey (NGS). The purpose of LOCUS is to simplify the office processing and adjustment of geodetic leveling, including, as a long-term goal, the submission of leveling projects to NGS for publication. LOCUS runs the same programs that NGS uses in-house to process and adjust submitted projects.


LVL_DH
LVL_DH Computes the expected leveled difference in height between two North American Vertical Datum of 1988 (NAVD 88) bench marks.

PC software is available for download.

Magnetic Declination
Compute values of Earth's magnetic field, including declination, with a service provided by NOAA's National Geophysical Data Center. Users should be aware that solar storms can cause intense, short-term disturbances in the magnetic field. If there is a major solar storm during a survey, values could be off by as much as 10 degrees! A link to NOAA's Space Environment Center is provided for checking the current space weather forecast.


NADCON
Transforms geographic coordinates between the NAD 27, Old Hawaiian, Puerto Rico, or Alaska Island datums and NAD 83 values. Recommended for converting coordinate data for mapping, low-accuracy surveying, or navigation. PC software is available for download.

See the pdf version of an article about NADCON that appeared in the Professional Surveyor magazine, February 2004

NAVD 88 Modelled Gravity
This process is similar to the Surface Gravity Prediction facility in this tool kit, but it uses the model surface developed for the NAVD 88 adjustment rather than current values of the gravity data base. The difference between these two sources of gravity values at a specific point should be no more than a few milligals. NAVD 88 Gravity is the modelled gravity that appears on NGS data sheets.

Online Adjustment User Services
Online versions of the popular NGS adjustment package and several supporting utilities. These programs are available for download from the NGS PC Software Download page under ADJUST Package.


Online Adjustment Utilities User Services
Online versions of the NGS adjustment utilities. These programs are available for download from the NGS PC Software Download page.


Online Positioning User Service (OPUS)
OPUS allows users to submit their GPS data files in RINEX format to NGS, where the data will be processed to determine a position using NGS computers and software. Each RINEX file that is submitted will be processed with respect to the 3 best national CORS sites.

See the pdf version of an article about OPUS that appeared in the Professional Surveyor magazine, May 2003 Volume 23, Number 5

State Plane Coordinates
GPPCGP: Converts NAD 27 State plane coordinates to NAD 27 geographic positions (latitudes and longitudes) and conversely. Includes defining constants for all NAD 27 plane coordinate zones.  PC software is available for download.

SPCS83: Converts NAD 83 state plane coordinates to NAD 83 geographic positions and conversely. Includes defining constants for NAD 83 coordinate zones. State plane coordinates are entered or computed to 1 mm accuracy, while the latitudes and longitudes entered or computed correspond to approximately 0.3 mm accuracy. PC software is available for download.

See the pdf version of an article about State Plane Coordinates that appeared in the Professional Surveyor magazine, January 2004

Surface Gravity Prediction
This process is designed to predict surface gravity at specified geographic position and topographic height. The value is determined by interpolation based on observed values. Observed gravity data in the NGS's Integrated Data Base are referenced to an absolute gravity datum.

Tidal and Orthometric Elevations
The tidal information and orthometric elevations of a specific survey control mark can be viewed graphically. Displayed will be the differences between the published NAVD 88 and NGVD29 and Mean Lower Low Water (MLLW) datums.

See the PDF version of an article about LVL_DH and Tidal and Orthometric Elevations that appeared in the Professional Surveyor magazine, July 2003 Volume 23, Number 7

U.S. National Grid Conversion
Converts between USNG, UTM, and geodetic latitude/longitude.
The Federal Geographic Data Committee (FGDC) has developed document FGDC-STD-011-2001 that defines the U.S. National Grid (USNG) System as an alpha-numeric reference standard to improve public safety, commerce, as well as aid the casual GPS user. The FGDC lists an Index Page and General Information & Resources that support this standard. The USNG provides an easy to use geoaddress system for identifying and determining locations with the help of a USNG gridded map and/or a USNG enabled GPS system.
PC software is available for download.

Universal Transverse Mercator Coordinates
The Universal Transverse Mercator Coordinate (UTM) system provides coordinates on a world wide flat grid for easy computation. It divides the World into 60 zones, each being 6 degrees longitude wide, and extending from 80 degrees south latitude to 84 degrees north latitude. The polar regions are excluded. The utilities in this package provide methods for converting between Geodetic Positions and UTM.
PC software is available for download.

VERTCON
Computes the modeled difference in orthometric height between the North American Vertical Datum of 1988 (NAVD 88) and the National Geodetic Vertical Datum of 1929 (NGVD 29) for a given location specified by latitude and longitude. This conversion is sufficient for many mapping purposes.

PC software is available for download.

See the pdf version of an article about VERTCON that appeared in the Professional Surveyor magazine, March 2004

XYZ Coordinate Conversion
Cartesian Coordinates (XYZ) allow for Geodetic quality three dimensional positioning on an earth centered ellipsoid. The utilities in this package provide methods for converting between Geodetic Latitude-Longitude-Ellipsoid_ht and XYZ on the GRS80 Ellipsoid.

PC software is available for download.

For more information contact NGS Information Services:
by email,
or call (301) 713-3242, Monday - Friday, 7:00 AM - 4:30 PM eastern time.

http://www.ngs.noaa.gov/TOOLS/program_descriptions.html 

Last updated by NGS.webmaster on December 22, 2021

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