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NGS Paper Demonstrates the Accuracy of Geoid System

January 22, 2021

In a few years, NGS will modernize the nation's height system. Instead of measuring inland heights from a "mean sea level," heights will be measured relative to a constant geopotential surface known as the geoid - a model of the shape of the Earth under the influence of gravity and rotation. By providing the shape of this undulating surface everywhere, the new system will allow surveyors to use GPS receivers to determine precise heights anywhere. In a new paper in the Journal of Geodesy, NGS describes a test of the geoid-based system in Colorado. The test demonstrated that the system has a relative accuracy of better than 5 centimeters in mountainous terrain - a worst case scenario for geoid determination. When combined with earlier surveys in Texas and Iowa (which showed better than 2 centimeter accuracy in smoother terrain), these results indicate the new national height system will provide more accurate elevations everywhere.

For more information, contact: Derek Vanwestrum