Use of Airborne On-the-Fly Kinematic GPS Data for Photogrammetric Mapping

Mushtaq Hussain, Riadh Munjy, James Appleton

Abstract:	Aerial triangulation procedure is routinely used for extension of sparsely distributed ground control for photogrammetric mapping. The use of camera positions derived through airborne GPS data collected during flight missions significantly reduces the need for ground survey operations. The position of the aerial camera, geometrically linked to an aircraft mounted antenna, is determined through differential kinematic data post-processed with reference to a known ground base station. The camera locations are usually needed with a precision better than 10cm for large-scale engineering mapping. In order to ensure the correct resolution of integer ambiguities to meet this precision, the collection of GPS data starts before take off while the aircraft is stationary. The need for maintaining continuous lock on 5 or more satellites during the entire mission places serious restrictions on the pilot for banking and turning maneuvers. Recent advancements in the GPS hardware and post-processing software enabling the resolution of ambiguities on-the-fly (OTF) offer an attractive alternative to eliminate flying restrictions. However, there is always the possibility that OTF ambiguities may not be correctly resolved. Consequently, not only the computed antenna positions may be in error, but these errors may also increase with time. In order to accommodate the possibility of any error in the camera positions arising from incorrect OTF ambiguity solutions, additional parameters are introduced in the photogrammetric bundle adjustment solution. The rationale for modeling such positional drift individually for each photo strip, or alternatively for the entire block is discussed.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	1653 - 1660
Cite this article:	Hussain, Mushtaq, Munjy, Riadh, Appleton, James, "Use of Airborne On-the-Fly Kinematic GPS Data for Photogrammetric Mapping," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 1653-1660.
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