Efficiency of Orientation Parameters on Georeferencing Accuracy of SPOT-5 HRG Level-1A Stereoimages

The efficiency of interior orientation parameters (IOPs) and exterior orientation parameters (EOPs) of the Satellite Pour l'Observation de la Terre 5 (SPOT-5) has been investigated with respect to georeferencing accuracy. A couple of SPOT-5 high-resolution geometric panchromatic level-1A stereoimages with 5-m ground sampling distance covering Zonguldak (Turkey) test field were used for this purpose using orientation parameters provided by metadata files. Ground control points are obtained by Global Positioning System observations. For the purpose of establishing geometric relationship between image and ground coordinate systems, an orbit-attitude parametric model has been used considering imaging geometry of sensor and ephemeris data of satellite. Adjustment consisting of the Gauss-Helmert model was performed in pre- and bundle-adjustment steps. Analyses show that the most efficient parameters are IOPs defined by look angles while EOPs are not significant on the accuracy. The validation of the EOPs and the correlation among IOPs and EOPs are also statistically analyzed. Different variations of point distribution and EOP configurations were preferred, achieving the georeferencing accuracies as ~ ±1 m and ~ ± 5 m at control and check points, respectively. All computations are performed via the developed program package called GeoSpot in Matlab platform.

I. Introduction

Satellite images are commonly preferred for geospatial applications. Since 1986, the Satellite Pour l'Observation de la Terre (SPOT) satellite series has begun a period that satellite images have never been as important as at the generation of geospatial information in the past. Although the highest resolution via SPOT-5 is 2.5 m, SPOT still retains its importance on the geospatial applications since parameters of imaging geometry and also many data such as ephemeris of satellite are delivered to the end user as a standard. So, an exact geometric relationship between image coordinate system (ICS) and ground coordinate system (GCS) can be established, and georeferencing is available with higher accuracy. This data distribution policy will be continued via SPOT-6 and SPOT-7 [1].