David B. Zilkoski

About David B. Zilkoski

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David B. Zilkoski has worked in the fields of geodesy and surveying for more than 40 years. He was employed by National Geodetic Survey (NGS) from 1974 to 2009. He served as NGS director from October 2005 to January 2009. During his career with NGS, he conducted applied GPS research to evaluate and develop guidelines for using new technology to generate geospatial products. Based on instrument testing, he developed and verified new specifications and procedures to estimate classically derived, as well as GPS-derived, orthometric heights.

Now retired from government service, as a consultant he provides technical guidance on GNSS surveys; computes crustal movement rates using GPS and leveling data; and leads training sessions on guidelines for estimating GPS-derived heights, procedures for performing leveling network adjustments, the use of ArcGIS for analyses of adjustment data and results, and the proper procedures to follow when estimating crustal movement rates using geodetic leveling data. Contact him at dzilkoski@gpsworld.com.

Posts by David B. Zilkoski

The differences between published Geoid18 and Geoid12B values in Southern Louisiana Posted on 01 Apr 2020 in the Opinions & Survey categories.

My February 2020 column provided an analysis of the differences between the latest published hybrid Geoid18 values provided on NGS’ Datasheet and the computed geoid height value using the published... Read more»

The differences between Geoid18 values and NAD 83, NAVD 88 values Posted on 05 Feb 2020 in the Opinions & Survey categories.

My last column, December 2019, highlighted the National Geodetic Survey’s (NGS) new Geoid Monitoring Service (GeMS); and, that NGS’ will be publishing a gridded geoid model GEOID2022 that will contain... Read more»

How NGS can implement a time-dependent geopotential datum Posted on 04 Dec 2019 in the Opinions & Survey categories.

The National Geodetic Survey (NGS) has published a technical report that describes options for how NGS can implement a time-dependent geopotential datum and thus a time-dependent geoid model. My last... Read more»

NGS releases beta version of NCAT 2.0 Posted on 02 Oct 2019 in the Opinions & Survey categories.

My last column highlighted the next phase of the National Geodetic Survey’s (NGS) GPS on Bench Marks program; that is, the development of the 2022 transformation model. It provided web... Read more»

Using the new interactive ‘GPS on Bench Marks’ map Posted on 07 Aug 2019 in the Opinions & Survey categories.

The National Geodetic Survey (NGS) is now developing the 2022 transformation model. Once again, NGS requests the assistance of the surveying and mapping community. This column provides examples to explain... Read more»

How to use the NGS Beta GEOID18 web map Posted on 05 Jun 2019 in the Opinions & Survey categories.

This column discusses the results of the National Geodetic Survey (NGS) beta hybrid Geoid18 model and the differences between the beta model and the official hybrid geoid model, Geoid12B. It... Read more»

NGS releases beta coordinates and multi-year CORS solution Posted on 03 Apr 2019 in the Featured Stories & Opinions & Survey categories.

My last column discussed the preliminary results of NGS’ second Multi-Year CORS Beta Solution of the National CORS. Since my last column, NGS announced the release of the beta version... Read more»

NGS to perform another Multi-Year CORS Solution Posted on 06 Feb 2019 in the Opinions categories.

The National Geodetic Survey (NGS) is performing another Multi-Year CORS Solution (MYCS) of the National CORS. This will mean the CORS coordinates will be updated to be consistent with the... Read more»