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Base 9 Geodesy provides training through a variety of presentations.  These can be given as live seminars (1-8 hours) or webinars (1-2 hours). Below are descriptions of topics commonly requested, but Base 9 Geodesy will work with you to craft a presentation suitable for your needs. Click here for reviews and to see where Dave has given his most recent workshops. For recorded examples of seminars, click here.

  • Fundamentals of Geodesy and Geodetic Datums: This program details the historical and contemporary developments of the horizontal and vertical geodetic datums of the U.S., the development of reference ellipsoids, geoid models and contemporary global coordinate systems, and the efforts of the National Geodetic Survey (NGS) to modernize the reference systems. To download a 1-page abstract of this workshop, click here.




  • Modernization of the National Spatial Reference System: During the next decade, enhancements and additions to the network of Global Navigation Satellite Systems (GNSS) will significantly improve the use of space-based positioning systems for surveying, mapping, charting, navigation and innumerable other applications. This presentation highlights the various elements that currently define the NSRS, and the activities NGS is engaged in to improve the capacity of and access to NSRS, including the rational for the planned datum redefinitions. To download a 1-page abstract of this workshop, click here.


  • GNSS-Derived Heights: This program discusses the various types of heights, methods for using Global Navigation Satellite System (GNSS) observations to derive orthometric heights related U.S. vertical datums, and the use of tools available from the National Geodetic Survey (NGS). To download a 1-page abstract of this workshop, click here.


  • The U.S. State Plane Coordinate System: The U.S. State Plane Coordinate System: This program discusses the foundational elements of the State Plane Coordinate System (SPC) and enhancements to NAD 83 from original release to present as they relate to changes in both the SPC and Universal Transverse Mercator Grid systems. The program highlights the relationship of geodetic and grid coordinate systems, and problems inherent in ground-based coordinate systems which are commonly referenced as "grid-to-ground." To download a 1-page abstract of this workshop, click here.

                                            For Information on State Plane Coordinate legislation, click here.

  • How You Can Invest in Improving the Status of Passive Control in the National Spatial Reference System: This presentation demonstrates how easy it is for users to provide the National Geodetic Survey (NGS) with improved information on the condition of passive control monuments, and how the OPUS Share Solution utility allows users to provide NGS information to update future geoid models and share their own geodetic control data from a national database. To download a 1-page abstract of this workshop, click here.


  • Datum Transformations: This seminar covers the relationship of and transformations between the several horizontal/geometric and vertical geodetic datums most commonly used in the U.S. and includes a demonstration of the transformation tools provided by NGS. The program closes with a review of the status of the changes to NAD 83 and NAVD 88 planned for 2022. To download a 1-page abstract of this workshop, click here.


Still not sure if a Seminar is right for you? Click here

Research and Computations


Base 9 Geodesy will research and prepare pre-North American Datum of 1927 (NAD 27) and pre-National Geodetic Vertical Datum of 1929 (NGVD 29) datum transformations to support nautical charts and other mapping and surveying data. Dave will provide technical advice relating to the definition, use of, and problems with current and historical geodetic datums of the U.S. and other elements of the NSRS.




Dave will complete reviews of professional papers and technical reports dealing with geodetic surveying and datums. Base 9 Geodesy will answer your questions about reference frames and datums as they pertain to your products, so that you can provide your clients with accurate and reliable information.