Title
Geometric Accuracy of Sentinel-1A and 1B Derived from SAR Raw Data with GPS Surveyed Corner Reflector Positions.
Abstract
The geometric accuracy of synthetic aperture radar (SAR) data is usually derived from level-1 products using accurately surveyed comer reflector positions. This paper introduces a novel approach that derives the range delay and azimuth shift from acquired SAR raw data (level-0 products). Therefore, the propagation path is completely retrieved from SAR pulse transmission up to the reception of the point target's backscatter. The procedure includes simple pulse compression in range and azimuth instead of full SAR data processing. By applying this method, the geometric accuracy of ESA's Sentinel-1 SAR satellites (Sentinel-iA and Sentinel-iB) is derived for each satellite overpass by using corner reflectors with precisely surveyed GPS positions. The results show that the azimuth bias of about 2 m found in level-1 products for Stripmap acquisitions is reduced to about 15 cm. This indicates an artificial bias arising from operational Sentinel-1 SAR data processing. The remaining range bias of about 1.0 m, observed in LO-products, is interpreted as the offset between the SAR antenna phase center and the spacecraft's center of gravity. The relative pixel localization accuracy derived with the proposed method is about 12 cm for the evaluated acquisitions. Compared to the full processed level-1 SAR data products, this accuracy is similar in the range direction, but, for the azimuth direction, it is improved by about 50% with the proposed method.
Year
DOI
Venue
2018
10.3390/rs10040523
REMOTE SENSING
Keywords
Field
DocType
synthetic aperture radar,Sentinel-1,geometric accuracy,point target evaluation
Phase center,Data processing,Corner reflector,Point target,Synthetic aperture radar,Backscatter,Remote sensing,Azimuth,Global Positioning System,Geology
Journal
Volume
Issue
ISSN
10
4
2072-4292
Citations 
PageRank 
References 
0
0.34
9
Authors
4
Name
Order
Citations
PageRank
Kersten Schmidt1143.31
Jens Reimann200.68
Nuria Tous-Ramon3394.90
Marco Schwerdt419629.75