ASAR IMG AND APG PRODUCTS:IMAGE QUALITY AND RADIOMETRIC PERFORMANCE

摘要

In this paper are reported the results of the analyses concerning the image quality and the radiometric performances of arndata set of ASAR Image Mode Geocoded products (IMG) and Alternating Polarization Geocoded (APG) products.rnSome preliminary analyses have been carried out: a Visual Inspection [1], which provides a quick overview of thernexpected product quality and possible main anomalies of the image, and a Format Verification [1], because arnverification of the correct product format is important to ensure complete product compatibility with all the toolsrndeveloped and available for the product analysis. Both the Visual Inspection and the Format Verification analyses havernbeen performed with IDL (the Interactive Data Language, of the Research Systems Inc., a software for data analysis,rnvisualization, and cross-platform application development) and EnviView (a free ESA application, that allows Envisatrndata users to open any Envisat data file, and examine its content) over each product.rnThe image quality has been inferred by measuring the Impulse Response Function (IRF analysis) of each product: thisrnanalysis take into account a measurement of the the resolution, both in range and azimuth direction, a measurement ofrnthe Peak Side Lobe Ratio (PSLR) and a measurement of the Integrated Side Lobe Ratio (ISLR) of the ImpulsernResponse Function of the ASAR transponders. Furthermore, an evaluation of the Absolute Calibration Factor (ACF) forrneach transponder have been made.rnThe Radiometric Resolution of each product has been evaluated by computing the Equivalent Number of Look (ENL)rnover homogeneous regions contained in the image.