Reducing Geoid Height Errors in Precision Navigation and Targeting

Neal A. Carlson, Daniel P. Martin, Sandra L. Berning and Peter G. Howe

Abstract:	Precision navigation and targeting systems typically employ surveillance or shooter aircraft positions derived from GPS. GPS provides high-accuracy position data referenced to the center of the earth, from which altitude above the WGS84 ellipsoid can be accurately computed. Conversely, ground target locations are often provided in terms of latitude, longitude, and elevation above the geoid. In particular, digital terrain elevation and feature data are referenced to the geoid. For precision navigation and targeting operations, geoid-referenced elevations must be converted to ellipsoid-referenced altitude to avoid vertical position errors equal to geoid height. Some military navigation systems employ a low-order tabular approximation of the geoid, and convert ellipsoid- referenced altitude to geoid-referenced elevation before output. However, residual errors in the tabular approxi- mation can be substantial in some parts of the globe. This paper characterizes the geoid approximation errors in several regions of interest. It then examines several alternate approximation methods that reduce geoid height errors to 1-2 meter or less, with modest data storage requirements. An attractive method based on multiresolu- tion interpolation is described. These more accurate geoid height models can substantially reduce vertical position errors in precision navigation and targeting operations.
Published in:	Proceedings of the 58th Annual Meeting of The Institute of Navigation and CIGTF 21st Guidance Test Symposium (2002) June 24 - 26, 2002 Hyatt Regency Hotel Albuquerque, NM
Pages:	102 - 113
Cite this article:	Carlson, Neal A., Martin, Daniel P., Berning, Sandra L., Howe, Peter G., "Reducing Geoid Height Errors in Precision Navigation and Targeting," Proceedings of the 58th Annual Meeting of The Institute of Navigation and CIGTF 21st Guidance Test Symposium (2002), Albuquerque, NM, June 2002, pp. 102-113.
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