A Test of Airborne Kinematic GPS Positioning for Aerial Photography: Methodology

G. Keel, H. Jones, G. Lachapelle

Abstract:	An airborne photogrammetric test was conducted by the Ministere de l'Energie et des Ressources, Government of Quebec, in November 1987 to assess the accuracy of. GPS for three-dimensional aircraft positioning. The GPS positioning and aerial photography were contracted out to Nortech Surveys (Canada) Inc., Calgary, and Hauts-Monts Inc., Quebec City. Nortech's differential kinematic positioning methodology and software were used; this multi-purpose software. which is based on the combination of code and carrier phase measurements. is operationally flexible and suitable for. real-time applications. The test was conducted with a Piper Aztec aircraft equipped with a Zeiss camera. Other equipment included two TI4100 receivers and Nortech-destgned Computer Addressable Precision Timing Systems (CAPTS) for the precise time-tagging of the camera shutter. The distance between the aircraft and the monitor station did not exceed 20 km. The internal consistency of the GPS positions was analyzed in terms of the flight misclosures from takeoff to landing. These misclosures were smaller than one metre in all three coordinate components. This is considered excellent in view of the satellite geometry available during the test. This was a blind test for Nortech Surveys and Hauts-Monts. The external accuracy was subsequently assessed independently by the Quebec Government using ground control stations [Moreau & Perron, 1988). The results confirmed the sub-metre accuracy quoted above. The use of this GPS positioning methodology in real-time would be well suited for a variety of extensive airborne applications where cost effectiveness becomes an important factor.
Published in:	Proceedings of the International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1988) September 19 - 23, 1988 The Broadmoor Hotel Colorado Spring, CO
Pages:	147 - 151
Cite this article:	Keel, G., Jones, H., Lachapelle, G., "A Test of Airborne Kinematic GPS Positioning for Aerial Photography: Methodology," Proceedings of the International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1988), Colorado Spring, CO, September 1988, pp. 147-151.
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