MSU developing CORS dashboard and geodetic program

May 1, 2024  - By
Photo: Dana Caccamise II

Photo: Dana Caccamise II

In my November 2023 GPS World newsletter, I highlighted the announcement made by the National Geodetic Survey (NGS) of the recipients of the National Oceanic and Atmospheric Administration (NOAA) FY 23 Geospatial Modeling Competition awards. The primary objectives of these projects are to modernize geodetic tools and models and to develop a geodetic workforce for the future. My last three GPS World newsletters — February 2024, March 2024 and April 2024 — highlighted three of the grantees, Scripps Institution of Oceanography, The Ohio State University, and Oregon State University that included developing models to address what NGS denotes as the Intra-Frame Deformation Model (IFDM) and creating geodesy curriculums that will help address the geodesy crisis. Changes in these geomatic programs will provide students with the skills in geospatial systems that will make available opportunities for employment in the public and private sectors. This newsletter will address the proposal by the fourth NGS geospatial modeling grant awardee, Michigan State University (MSU).

First, it should be noted that this award is denoted as the MSU geospatial modeling award; that said, the execution of the project will be led by MSU, along with two sub-awardees — University of Alaska Fairbanks (UAF) and Michigan Tech University (MTU). Jeffrey Freymueller and Julie Elliott are the MSU grant’s principal investigators (PI). They provided me with information about the goals and objectives of their grant proposal.

The MSU proposal includes enhancing software and monitoring capabilities for NGS, enhancing graduate-level geodetic education and providing opportunities for graduate and undergraduate students to be exposed to geodetic science. Again, focusing on geodesy curriculums will help address the geodesy crisis and will provide students with the skills in geospatial systems that will increase their opportunities for employment in the public and private sectors. The proposal has two main goals and objectives.

Goals and objectives

CORS Dashboard 

  • Build an online, web-based CORS dashboard that will support monitoring of the continuously operating reference station (CORS) network.
  • Making it easier to continually validate the current position of CORS sites to the existing motion models (IFDM).
  • To validate and correct the motion models themselves in the presence of time-dependent tectonic and volcanic activity.


  • Work with partner universities toward developing and establishing a consortium model for future distributed geodetic degree programs that leverage the capabilities and capacity of multiple universities.
  • Develop new course material for graduate level geodetic education that is intended for hybrid or asynchronous remote delivery and the establishment of a formal degree program.
  • Host summer undergraduate interns who will work on a variety of geodetic projects including the CORS dashboard.
  • Two graduate students will be supported to work on various aspects of the proposed work at MSU and MTU.

Anyone using NGS’s “user-friendly” software knows that they are working on improving their web-based services. However, NGS still needs help from outside users.

I want to emphasize that I am not criticizing NGS’s products and services. I worked for NGS for over three decades, and I personally know that NGS has limited resources to accomplish too many tasks. NGS needs to focus on the science and get help with the development of models, tools and the dissemination of results and data. That is one of the reasons that these geospatial modeling grants are important to all users of the National Spatial Reference System (NSRS).

The proposed CORS Dashboard will be very useful to NGS employees monitoring the CORS and evaluating the IFDM. The proposal highlights that users of NGS products and services have various precision and accuracy requirements and that all users expect that NGS products will be sufficiently precise and accurate to meet their positioning needs. Their design of the CORS Dashboard will provide a tool for effectively monitoring and assessing a CORS site status and the validity of its coordinates. The first phase of this tool is being developed for internal use at NGS. However, in my opinion, after all the bugs have been identified and dealt with, NGS will release a version for the user.

Not all CORS are created equal. So, having a CORS Dashboard that quickly identifies and notifies CORS users of a systematic deviation at a site, regardless of cause, will avoid promulgating erroneous positions to users. In addition, providing statistical information about a CORS site such as short- and long-term plots and their residuals would provide users with helpful information for planning a GNSS project. The metadata of CORS is extremely important since most of the CORS included in the NOAA CORS Network are not maintained by NGS.

CORS managers are supposed to notify NGS when they make any change to their CORS site such as an antenna change and any changes surrounding the CORS site, including new vegetation or construction that could cause potential obstructions. The CORS Dashboard will help identify issues with CORS before users include them in their projects.

NGS’s OPUS Project online user guide provides information on selecting the best CORS.  The following is from the user guide:

  • Using the centered time-series plots, select the candidates with RMS (in northing, easting, and up) less than 2 cm. Candidates with large spikes, data gaps or discontinuities should be rejected. Selecting candidates in this manner will provide some assurance that the published coordinates and velocities at the CORS agree with the daily solutions for the CORS.
  • The best CORSs should have “consistent” data depicted in 90-day short-term time-series plots. NGS processes each day of GNSS data collected at each CORS and plots the differences between the resulting coordinates and the published coordinates on short-term time-series plots (in terms of delta northing, easting, and up). These plots can be accessed for every CORS at CORS with plots that depict significant biases from the published coordinates (more than 2 cm in northing, easting, or more than 4 cm), spikes or data gaps should be avoided.

NGS has developed a Beta CORS Time Series Tool that provides information that assists users in the selection of appropriate CORS for a project. The tool computes and displays the residual differences from the daily NGS OPUS-NET solutions with the coordinates from the official CORS’ coordinate functions. The tool also generates a summary table with the mean, standard deviation, and root-mean-square error of the residuals. On April 24, 2024, NGS announced the release of a beta version of a new NOAA CORS Network (NCN) Station Web Page. According to the announcement, each CORS in the NCN will have its own page with data, metadata, maps and photos for that station displayed in a modular layout so information is easily found all in one location. I will describe this new beta site in a future newsletter.

The new, modernized NSRS will offer time-dependent coordinates based on an IFDM. This has been described in previous GPS World newsletters (February 2022 and August 2022). The MSU proposal includes developing a model that accounts for crustal movements — such as earthquakes, slow slip events, and volcanic eruptions, — as well as slower, cumulative growth of error due to post-seismic deformation, surface loading (ice or water changes) and changes in rates of human-induced subsidence due to fluid withdrawal. Like any model, the IFDM model will have uncertainties. Being able to provide a realistic estimate of the uncertainties of the IFDM is very important. The PIs of the proposal have extensive knowledge and experience in generating models and uncertainties. As noted in their proposal, the “problem” may not be an issue with the site or the equipment but with the model. See the box titled “Excerpt from the MSU Proposal.”  I have highlighted several sections that I believe are important to the users of the new, modernized NSRS.

Excerpt from the MSU ProposalExcerpt from the MSU Proposal (2)

As anyone who has been following my newsletters knows, I have been highlighting the geodesy crisis and programs that advance the science of geodesy — July 2020, November 2022, and December 2022. The proposal includes developing geodetic science courses that will be optimized for hybrid or asynchronous online courses that address advanced technical topics on GNSS, InSAR, map projections, reference frames, and adjustment theory. This will build on existing programs at MSU, UAF and MTU that will provide an online graduate degree in geodesy. MSU envisions this to be a step toward a consortium-based enhanced graduate-level education that provides a range of course options and flexibility. The university believes that there will be opportunities to expand the consortium in the future. The courses have not been finalized yet,  but below are some of the topics and concepts that are being considered for the program.

Topics and Concepts

Map Projections

Map projections, geodetic datums, grid systems and transformations. Use of mapping software including GMT.


Geodetic Models

Course provides solid geospatial background in geodetic reference frames, datums, geoids and reference ellipsoids. 2D and 3D geodetic network adjustments are considered based on 3D spherical models.


Modern Geodesy and Applications

Modern geodetic methods including GPS, measuring steady or time-variable motions, the physical models that are used to interpret these observations and applications to active geological processes, the cryosphere and hydrology.



Geodetic Methods and Applications

Theory and application of modern geodetic tools to measure Earth’s surface deformation with emphasis on GPS and InSAR. Basics of data processing; evaluation of signals and modeling of their sources; applications include magma systems, earthquake cycle and hydro- and cryosphere. Labs in Python require programming experience


Geodetic Data Processing and Analysis

Course provides students hands-on experience in the selection, processing and analysis of geodetic data sets, particularly InSAR and GNSS. Selection of data from diverse sources, evaluation of data strengths and weaknesses, processing and analysis of data and application to the investigation of geological problems.

Solid Earth Geophysics and Geodynamics

Theory and applications of solid-Earth geophysics including geochronology, geothermics, geomagnetism and paleomagnetism, geodesy and gravity, rheology and seismology.




Foundations of Geophysics

Applications of continuum mechanics, heat flow theory and potential theory to geophysical, geologic and glaciological problems. Topics such as postglacial rebound, non-Newtonian fluid flow, thermal convection, stress-relaxation, rheology of Earth materials, gravity and magnetics will be discussed. Emphasis will be placed on methods and tools for solving a variety of problems in global and regional geophysics and the geophysical interpretation of solutions.

Positioning with GNSS

In-depth study of GPS, GLONASS, Galileo, COMPASS satellite systems; theory and processing of global positioning measurements.

Intro Numerical Tools for Earth and Environmental Sciences

Introduction to Linux and C including numerical methods, integration, curve-fitting and differential equations with an emphasis on applications to the geological sciences.



Programming and Automation for Geoscientists

Basic concepts of computer programming and effective task automation for computers, with an emphasis on tools and problems common to the geosciences and other physical sciences. Use of Python, Jupyter Notebooks, shell scripting and command line tools, making scientific figures, maps and visualizations.



Data Analysis and Adjustments

Course explores fundamentals of mathematical error propagation theory, including various observation equations, least squares adjustment and Kalman filter methods. Blunder detection, decorrelation and inversion of patterned large matrices processes are considered. Involves analysis of position estimation deploying geospatial measurements.



Inverse Problems and Parameter Estimation

An inverse problem uses observations to infer properties of an unknown physical model. This course covers methods for solving inverse problems, including numerous examples arising in the natural sciences. Topics include linear regression, method of least squares, estimation of uncertainties, iterative optimization and probabilistic (Bayesian) and sampling approaches.

Numerical Analysis

Direct and iterative solutions of systems of equations, interpolation, numerical differentiation and integration, numerical solutions of ordinary differential equations and error analysis.

3D Surveying and Modeling with Laser Scanning Data

Theory and application of terrestrial lidar scanning. Typical application scenarios are also included. Intensive lab component provides hands-on experience in lidar point cloud processing and visualization.


Advanced Photogrammetry – Satellite Photogrammetry

Fundamentals of spaceborne imaging systems relevant to topographic mapping. Imagery products —preprocessing levels and metadata. Specific methods of space photogrammetry. Review of contemporary spaceborne imaging systems and imagery products available. Airborne non-frame sensors and photogrammetric processing of the imagery.



Microwave Remote Sensing

The principles and applications of active and passive microwave remote sensing with emphasis on spaceborne remote sensing of the Earth’s atmosphere, land and oceans. The laboratory section will provide hands-on experience on special processing techniques and the possibility of using these techniques for a student-defined term project in areas of geology, volcanology, glaciology, hydrology and environmental sciences


InSAR and its Applications

Introduction to the concepts of repeat-pass spaceborne SAR interferometry. Practical use of the technique to derive displacements of the solid Earth, glaciers and ice sheets to a precision of a few centimeters and accurate digital elevation models of the Earth’s surface.

As previously stated, these courses have not been finalized. An important aspect of the courses is that they contain content that will provide students with the skills and knowledge in geodetic concepts to help address the geodesy crisis in the United States.

I first mentioned the need for more trained geodesists in my July 2020 article for the “First Fix” column of GPS World, where I stated that the shortage of U.S.-trained geodesists poses a significant economic risk for the United States. In that column, I mentioned how geodetic science and technology now underpin many sciences, large areas of engineering such as driverless vehicles, UAVs, navigation, precision agriculture, smart cities and location-based services.

My November 2022 GPS World Newsletter highlighted “The inverted geospatial pyramid” graphic, which depicts how the entire $1 trillion geospatial economy is supported and dependent on geodesy. A lack of geodetic expertise in the United States presents a significant challenge, with future impacts on positioning, navigation, mapping and dependent geospatial technologies. These changes in the geomatic programs at the universities being funded by NGS’s geospatial modeling grants will provide students with the skills in geodetic concepts that will provide opportunities for employment in the public and private sectors involved with geospatial technology.

This newsletter and my past three GPS World newsletters highlighted the four NGS Geospatial Modeling grantees, which included creating geodesy curriculums that will help address the geodesy crisis. The MSU proposal describes a consortium-based enhanced graduate-level education program that will provide a range of course options and flexibility. I believe their proposed hybrid or asynchronous online program will provide more opportunities for individuals to study geodesy and advance the science of geodesy.

One final note about the NGS Geospatial Modeling Grants. On June 4, 2024, Brad Kearse, director of NGS, will moderate a session at the UESI Surveying and Geomatics 2024 Conference held in Corvallis, Oregon, on June 4 to 5, 2024. This will be a good opportunity for participants to obtain a better understanding of the geospatial modeling grants.

Lunch & panel discussion: NGS Geospatial Modeling Grants panel session

Moderator: Brad Kearse, Acting Director, NGS

The NGS Geospatial Modeling grant program is focused on modernizing and improving the National Spatial Reference System (NSRS) and address emerging research problems in the field of geodesy. A secondary objective of this funding opportunity is to support a geodesy community of practice in collaboration with federal and nonfederal stakeholders to address the nationwide deficiency of geodesists and improve the coordination and use of geospatial data. This panel session will explore the research and other activities underway from recipients of the most recent round of the NGS Geospatial Modeling Grant Program.

About the Author: David B. Zilkoski

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