Sentinel-2 output format

MAJA outputs products as a collection of directories, each of which refer to the given input L1C product, together with a log file. As an example:

SENTINEL2A_20170706-090107-511_L2A_T33KWP_C_V1-0/
SENTINEL2B_20170701-090105-359_L2A_T33KWP_C_V1-0/
S2A_MSIL1C_20170706T083601_N0205_R064_T33KWP_20170706T090107.log
S2B_MSIL1C_20170701T084019_N0205_R064_T33KWP_20170701T090105.log
..

Each product directory is named according to the sensor, date of acquisition, level, tile ID and version. It contains a collection of GeoTIFF and XML files:

• a DATA/ directory for product meta-data inherited from the L1C
• a MASK/ directory with:
  • *_CLM_*.tif : the cloud mask
  • *_DTF_*.tif:
  • *_DFP_*.tif:
  • *_EDG_*.tif : the edge mask (actual border of the image within the tile extent)
  • *_IAB_*.tif : the water vapour and AOD interpolation mask
  • *_MG2_*.tif : the geophysical mask
  • *_SAT_*.tif : the saturation mask
• *_SRE_B*.tif : surface reflectance of band B* corrected for adjacency (divide by 10000 to convert Digit Number to surface reflectance)
• *_FRE_B*.tif : surface reflectance of band B* corrected for adjacency and topography effects (divide by 10000 to convert Digit Number to surface reflectance)
• *_ATB_*.tif : a 2-bands GeoTIFF with:
  • band 1 being the water vapour (divide by 20 to convert Digit Numbers to g/cm2);
  • band 2 being the Aerosol Optical Thickness (divide by 200 to convent Digit Number to AOD (-)
• *_MTD_ALL.xml : product meta-data
• *_QKL_ALL.jpg : product quicklook from bands (B4, B3, B2)

The suffix “_R1” and “_R2” relate to the 10m-resolution and the 20m-resolution bands respectively.

Product meta-data

Although each GeoTIFF surface reflectance file is self-sufficient for geolocation of the data, you will need some of the information stored in the XML meta-data file to properly use a MAJA product. Among other, the scale factor values such that <value> = <digit number> / <quantification value>, and the NODATA values:

    <Radiometric_Informations>
        <REFLECTANCE_QUANTIFICATION_VALUE>10000</REFLECTANCE_QUANTIFICATION_VALUE>
        <WATER_VAPOR_CONTENT_QUANTIFICATION_VALUE>20</WATER_VAPOR_CONTENT_QUANTIFICATION_VALUE>
        <AEROSOL_OPTICAL_THICKNESS_QUANTIFICATION_VALUE>200</AEROSOL_OPTICAL_THICKNESS_QUANTIFICATION_VALUE>
        <Special_Values_List>
            <SPECIAL_VALUE name="nodata">-10000</SPECIAL_VALUE>
            <SPECIAL_VALUE name="water_vapor_content_nodata">0</SPECIAL_VALUE>
            <SPECIAL_VALUE name="aerosol_optical_thickness_nodata">0</SPECIAL_VALUE>
        </Special_Values_List>

You’ll also find quality information related eg. to the cloud cover, snow cover, hot spot detection, etc.. under the <Quality_Information> group:

                    <Global_Index_List>
                        <QUALITY_INDEX name="CloudPercent">0</QUALITY_INDEX>
                        <QUALITY_INDEX name="SnowPercent">0</QUALITY_INDEX>
                        <QUALITY_INDEX name="RainDetected">false</QUALITY_INDEX>
                        <QUALITY_INDEX name="HotSpotDetected">false</QUALITY_INDEX>
                        <QUALITY_INDEX name="SunGlintDetected">true</QUALITY_INDEX>
                    </Global_Index_List>

Whenever you need to trace back the version of MAJA used to process a given product, it is stored at:

<PRODUCTION_SOFTWARE>MAJA 4.6.0</PRODUCTION_SOFTWARE>

Finally, the structure of the different masks are described in the <Mask_List> subgroup and detailed in the section below.

Product masks

The mask layers are bitmasks, not to be confused with classified layers. Each pixel of a bitmask is a 8-bit unsigned integer which could be considered as a vector of 8 booleans (either 0 or 1). Each bit defaults to 0, unless the pixel matches a given mask category and changes to 1.

As an example, consider a cloud mask pixel whose value is 35. This integer is stored as a sequence of bits numbered from 0 to 7. It should be interpreted as follow :

Here, the pixel is affected by a cloud or a cloud shadow (bit 0), and matches the cloud category (except the thinnest) (bit 1), and was detected by the multi-temporal threshold (bit 3). This byte 00001011 is stored as a 8-bit integer of value 11 as illustrated below :

Masks bitcodes

The tables below describe the different bitmasks produces by MAJA