GIS in Action 2026

Ground control points (GCPs) are highly useful in UAS photogrammetry and Lidar collection for a variety of infrastructure mapping applications. It is important that GCPs reflect the true elevation at the point location where they are registered. One common problem with registering a GCP is that there is distortion in the observed elevation related to the geoid separation height. An application was developed for orthometric correction of ground control points using a Geoid API provided by the National Oceanic and Atmospheric Administration (NOAA) which outputs elevations that are more accurate and more useful for drone mapping. This application was built into a Python toolbox that was made accessible to the Massachusetts Dept. of Transportation (MassDOT) for future drone missions.