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@@ -497,6 +497,18 @@ In MOD09A1: It seems that cloud related info is not filled properly in the
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standard QC (MOD09A1 in this module) since version 3, State-QA 500m images
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(MOD09A1s in this module) should be used (see Vermote et al., 2008).
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+MOD11A2 quality control (QC) bands do not have a FillValue (No-data) according
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+to <a href="https://lpdaac.usgs.gov/dataset_discovery/modis/modis_products_table/mod11a2_v006">MODIS Land Products site</a>.
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+However, the metadata of the QC bands (i.e.: <tt>gdalinfo QC_band</tt>) shows <tt>No-data=0</tt>.
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+This value is then transformed into GRASS NULLs when data is imported though
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+<a href="r.in.gdal.html">r.in.gdal</a>. Applying <em>i.modis.qc</em> on those QC bands
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+will not give the expected range of values in the different QC bits. Therefore,
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+before using <em>i.modis.qc</em>, the user needs to set the NULL value in QC bands
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+back to zero (i.e.: <tt>r.null map=QC_band null=0</tt>) or just edit the metadata with GDAL
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+utilities before importing into GRASS GIS. This is a known issue for MOD11A2
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+(8-day LST product), but other MODIS products might be affected as well.
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+
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+
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<h2>TODO</h2>
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Add more daily products.
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