On the influence of sub-pixel position correction for PS localization accuracy and time series quality
M. Yang (TU Delft - Mathematical Geodesy and Positioning, Wuhan University)
P Dheenathayalan (TU Delft - Mathematical Geodesy and Positioning)
Francisco Dekker (TU Delft - Mathematical Geodesy and Positioning)
Freek Van Leijen (TU Delft - Mathematical Geodesy and Positioning)
Mingsheng Liao (Wuhan University)
Ramon Hanssen (TU Delft - Mathematical Geodesy and Positioning)
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Abstract
Persistent Scatterer Interferometry (PSI) is a time series remote sensing technique to estimate displacements of geo-objects from the interferometric phases of selected Persistent Scatterers (PS). The relative position of a scatterer within a resolution cell causes an additional phase contribution in the observed phase, which needs to be accounted for in PSI processing. Here we analyze the influence of this sub-pixel position correction on point localization and displacement quality. Apart from a theoretical evaluation, we perform experiments with TerraSAR-X, Radarsat-2, and Sentinel-1, demonstrating various levels of improvement. We show that the influence of the sub-pixel correction is significant for the geolocation of the scatterer (meter-level improvement), modest for the elevation estimation (centimeter-level improvement), and limited for the displacement estimation (submillimeter-level). For displacement velocities, we find variations of a few tenths of a millimeter per year. The effect of sub-pixel correction is most dominant for large orbital baselines and short time series.
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