GPS Precise Point Positioning Software for Ground Control Point Establishment in Remote Sensing Applications

In practice, the coordinates necessary in geometric rectification are usually derived from medium scale maps such as 1:50,000 or 1:25,000 scale topographic maps. However, the total positional error of any point on these maps may exceed 1.0 mm due to pointing uncertainty, position shift, and exaggeration from cartographic generalization, paper shrinkage, etc. As spatial resolution of satellite imagery such as Landsat 7 panchromatic, ASTER VNIR, Spot 5 are now in the range of 5–15 m, ground control point (GCP) coordinates derived from medium scale maps are no longer acceptable since the magnitude of positional error may be up to several pixels. Larger scale maps may be used, but their coverage is limited to urban and high-density areas. This problem may be alleviated by adopting differential global positioning system (DGPS) techniques which can provide coordinates of up to 1 m accuracy. However, the technique is effective only for short baselines because the unmodeled errors are directly proportional to the...