GSC Sentinel-2 PDGS OCD - Emits - ESA
GSC Sentinel-2 PDGS OCD - Emits - ESA
GSC Sentinel-2 PDGS OCD - Emits - ESA
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<strong>GSC</strong> <strong>Sentinel</strong>-2 <strong>PDGS</strong> <strong>OCD</strong><br />
Issue 1 Revision 2 (draft) - 25.07.2010<br />
GMES-GSEG-EOPG-TN-09-0008<br />
page 136 of 350<br />
radiometric and geometric corrections including ortho-rectification and spatial registration on a<br />
global reference system with sub-pixel accuracy to facilitate multi-temporal data exploitation.<br />
The MSI Level-1C product will provide Top-Of-Atmosphere (TOA) reflectance measurements<br />
with all metadata necessary to convert it in radiances. The Level-0 consolidation and Level-1<br />
data-processing steps are based on the GPP algorithms [RD-31].<br />
Level-0 consolidation will append all necessary metadata for Level-0 data long-term archiving<br />
and upper level processing.<br />
Level-1 processing includes the three-step processing to generate Level-1A, Level-1B and<br />
Level-1C data starting from the consolidated Level-0 data. These three levels correspond<br />
respectively to the S2MSI1A, S2MSI1B and S2MSI1C data-products baselined in section 4.4.<br />
The accommodation of the processing workflow defined for the GPP into the distributed<br />
<strong>PDGS</strong> operational context has nevertheless required a careful analysis (cf. [RD-30]) of the<br />
specific constraints imposed by the Level-1 algorithm (cf. section 4.3.9) to provide<br />
systematically and globally the products with a guaranteed timeliness and quality.<br />
This section provides an outline of the operational Level-0 consolidation and Level-1<br />
processing approach adapted for the <strong>PDGS</strong>. After an outline description of the algorithm<br />
logic, the context of Level-1 processing in the distributed <strong>PDGS</strong> will be presented followed by<br />
the main adaptation made in accommodating the processing workflow defined for the GPP as<br />
justified by [RD-30].<br />
4.5.4.5.1 Level-0 Consolidation and Level-1 Processing Logic<br />
The <strong>PDGS</strong> Level-0 consolidation and Level-1 processing breakdown is based on the<br />
<strong>Sentinel</strong>-2 GPP algorithm (cf. [RD-31]). The processing workflow from instrument raw data<br />
(Instrument Source Packets, ISPs) to Level-1C data is depicted on Figure 4-23. The<br />
processing sequence is decomposed in the following steps:<br />
Level-0 Consolidation Processing<br />
o Level-0 Viewing Model Initialisation (performed within the GPP by the Init_Loc_Inv<br />
IAS). This processing step computes the viewing model for the generation of the<br />
preliminary quicklook.<br />
o Preliminary Quick-Look Processing (performed within the GPP by the Init_Loc_Inv<br />
IAS). This includes the preliminary quick-look (PQL) resampling and the computation<br />
of ancillary data for consolidated Level-0 product.<br />
o Preliminary Cloud Mask Processing (performed within the GPP by the Cloud_Inv<br />
IAS). This processing step generates the cloud mask from the preliminary quicklook<br />
based on spectral criteria.<br />
o Preliminary Quick-Look Compression (performed within the GPP by the<br />
JP2KCompression IAS). Performs the compression of the preliminary quick-look.<br />
Level-1A Processing<br />
o Level-1 Viewing Model Initialisation (performed within the GPP by the Init_Loc_Prod<br />
IAS). This processing step computes the viewing model that will be used to initialize<br />
Level-1B processing.<br />
<strong>ESA</strong> UNCLASSIFIED – For Official Use<br />
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The copyright of this document is the property of <strong>ESA</strong>. It is supplied in confidence and shall not be reproduced, copied or<br />
communicated to any third party without written permission from <strong>ESA</strong>.
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