Chapter H. Geodetic Tool Kit

The NGS Geodetic Tool Kit is a collection of geodetic programs. All can be run online, some have versions that can be downloaded, installed, and run locally.

Geodetic Tool Kit programs applicable to this Geodesy topic include:

GEOIDXX - computes the geoid height at a user specific location. There are versions of this program for geoid models generated in 1999, 2003, 06, 09, 12, and 18

NAVD88 Modelled Gravity

Surface Gravity Prediction

DEFLECXX - computes the N-S, E-W components and La Place correction at a user specified location. Versions for 1999, 2009, 2018

VERTCON - Elevation transformation between NGVD 29 and NAVD 88.

NCAT (NGS Coordinate Conversion and Transformation Tool) is for 1D, 2D, and 3D transformations and conversions. It replaces other single purpose programs (eg, NADCON, VERTCON, etc).

Whether you use any of the programs or not, you may be using information generated by one or more. Figure H-1 is part of the datasheet for control point James Reset.

Figure H-1 James Reset Datasheet

At the far right of each position information element is an indication how it was obtained.

• ADJUSTED means it was measured and included in the adjustment which created the element.
• The next three elements were generated using the Geodetic Tool Kit - each line ends with the name of the program used.

NGS software is the federal agencies' standard for converting or transforming position information. Many software developers incorporate NGS methodologies in their applications. You may not use these directly, but chances are some of your software does.