-
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.
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.
-
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 only the coterminous U.S.
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.
-
HTDP
-
This horizontal time-dependent positioning software program allows users
to predict horizontal displacements and/or velocities at locations throughout
the United States and its territories. This software also enables users to update geodetic
coordinates and/or observations from one date to another.
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.
-
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.
NOAA's Coastal Services Center offers a windows utility
that does NADCON conversions using shapefiles as input and output.
-
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 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 text 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.
-
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 U.S. National Grid (USNG) System is an alpha-numeric reference
system that overlays the UTM coordinate system. It is a Federal
Geographic Data Committee (FGDC) standard developed to improve public
safety, commerce, as well as aid the casual GPS user. 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.
-
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.