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27 January 1997 SPOT Histogram data base
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Since mid-87, the histograms of all the SPOT cloud-free images processed in Toulouse (France), Kiruna (Sweden) and by SICORP (USA) have been stored in a data base. Thanks to the continuous effort made to calibrate the SPOT HRVs, the observed reflectances for the four SPOT spectral bands can be estimated. Reflectances can be visualized on world maps for a given period and are mainly used to tune the viewing gains. This calibration procedure is now operational for SPOT2 and SPOT3: the new programming center automatically adjusts the on-board electronic gains according to the landscape to optimize the image dynamics while avoiding saturation. This paper presents the basic design of the base, from the reception of histograms to the creation of gain files. Reflectance maps show the data base contents in terms of world coverage. The accuracy of the computed reflectances is discussed and the problem of geographic areas with no data in the base in considered. We also briefly describe other SPOT Histogram Data Base applications such as sizing an optical sensor, and searching for uniform areas for relative calibration or stable areas for absolute temporal calibration. Finally we discuss future enhancements such as using data from other sensors like VEGETATION, which will fly on SPOT4 and would provide information for the mid- infrared band to optimize SPOT4 HRVIR image acquisition.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Aime Meygret, Magdeleine C. Dinguirard, Patrice J. Henry, Laurent Poutier, Sandrine Lafont, and Philippe Hazane "SPOT Histogram data base", Proc. SPIE 2957, Advanced and Next-Generation Satellites II, (27 January 1997);


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