Journal of Surveying Engineering

This paper describes an experiment for a proposed scheme using on-board satellite data to perform three-dimensional positioning for a pair of SPOT stereostrips. Based on the sampling geometry of French SPOT satellite images, we first adjusted the on-board parameters by incorporating a small number of ground control points (GCPs). Then a procedure for three-dimensional modeling was performed as follows. The central features of the proposed scheme are: (1) use of on-board data to initialize orbit parameters and attitude data for the satellite; (2) correction of on-board parameters with low order polynomials; (3) use of reverse transformation to check the collinear relationship between object space and image space for the GCPs; (4) adjustment of attitude data for the satellite to minimize the error in terms of the GCP collinearity; and (5) space intersection. Experimental results indicate that, for a SPOT panchromatic stereostrip with a 0.6 base-to-height ratio and a 45 km by 280 km stereo model area, the root-mean-square-error for 3-D positioning is less than 8 m in each direction when only 4 GCPs are used.

Field and laboratory tests of a shipborne hydrographic survey system were conducted. The system consists of two 12-channel GPS receivers (one onboard, one fixed on shore), a digital acoustic fathometer, and a digital heave-pitch-roll (HPR) recorder. Laboratory tests of the HPR recorder and fathometer are documented. Results of field tests of the isolated GPS system and then of the entire suite of instruments are presented. A method for data reduction is developed to account for vertical errors introduced by roll and pitch of the survey vessel, which can be substantial (decimeters). The GPS vertical position data are found to be reliable to 2–3 cm and the fathometer to 5 cm in the laboratory. The field test of the complete system in shallow water (<2 m) indicates absolute vertical accuracy of 10–20 cm. Much of this error is attributed to the fathometer. Careful surveying and equipment setup can minimize systematic error and yield much smaller average errors.

Double differencing of the carrier phases is a popular technique in global positioning system (GPS) surveying for eliminating receiver and satellite clock errors. However, because each global navigation satellite system (GLONASS) satellite transmits a different carrier frequency, it is not straightforward to constrain double difference integer ambiguities from GLONASS carrier phases. Various solutions are reviewed, following the formalism traditionally applied to GPS observations and focusing on the receiver clock errors. Mixed GPS/GLONASS data are used to demonstrate the impact of receiver clock errors on GLONASS double differences carrier phases.