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NGS Geodetic Tool Kit Program Descriptions
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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.
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Online Adjustment User Services
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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.
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Online Adjustment Utilities User Services
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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)
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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
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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.
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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
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Surface
Gravity Prediction
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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.
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Tidal
and Orthometric Elevations
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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
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U.S. National Grid Conversion
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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.
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PC software is available for download.
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Universal Transverse
Mercator Coordinates
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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.
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PC software is available for download.
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VERTCON
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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
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XYZ Coordinate
Conversion
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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.
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