Output Format

Note

It is recommended to output the “improPhed” Level 2 data to the Level 2 directory, i.e. DIR_LOWER = DIR_HIGHER. This way, the refined dataset is appended to the original dataset as a separate product. Thus, after running this submodule, two surface reflectance versions are available for each date. The new product will have higher spatial resolution (more pixels) than the other products (e.g. QAI). higher-level can digest this data structure, and the user can choose to use the original BOA or the refined product (USE_L2_IMPROPHE).

Data organization

The data are organized in a gridded data structure, i.e. data cubes. The tiles manifest as directories in the file system, and the images are stored within.

See also

Check out this tutorial, which explains what a datacube is, how it is parameterized, how you can find a POI, how to visualize the tiling grid, and how to conveniently display cubed data.

Data Cube definition

The spatial data cube definition is appended to each data cube, i.e. to each directory containing tiled datasets, see Data Cube definition.

Naming convention

Following 29-digit naming convention is applied to all output files:

Example filename: 20160823_LEVEL2_SEN2A_IMP.tif

Digits	Description
1–8	Acquisition date as YYYYMMDD
10–15	Product Level
17–21	Sensor ID
	LND04	Landsat 4 Thematic Mapper
	LND05	Landsat 5 Thematic Mapper
	LND07	Landsat 7 Enhanced Thematic Mapper
	LND08	Landsat 8 Operational Land Imager
23–25	Product Type
	IMP	ImproPhed Bottom-of-Atmosphere Reflectance
27–29	File extension
	tif	image data in compressed GeoTiff format
	dat	image data in flat binary ENVI format
	hdr	metadata for ENVI format

File format

The images are provided with signed 16bit datatype and band sequential (BSQ) interleaving in one of the following formats:

• GeoTiff

  This is the recommended output option. Images are compressed GeoTiff images using LZW compression with horizontal differencing. The images are generated with internal blocks for partial image access. These blocks are strips that are as wide as the TILE_SIZE and as high as the BLOCK_SIZE.

• ENVI Standard format

  This produces flat binary images without any compression. This option might seem tempting as there is no overhead in cracking the compression when reading these data. However, the transfer of the larger data volume from disc to CPU often takes longer than cracking the compression. Therefore, we recommend to use the GeoTiff option.

Metadata

Metadata are written to all output products. For ENVI format, the metadata are written to the ENVI header (.hdr extension). For GeoTiff format, the metadata are written into the GeoTiff file. If the metadata is larger than allowed by the GeoTiff driver, the excess metadata will be written to an “auxiliary metadata” file with .aux.xml extension. FORCE-specific metadata will be written to the FORCE domain, and thus are probably not visible unless the FORCE domain (or all domains) are specifically printed:

gdalinfo -mdd all 20160823_LEVEL2_SEN2A_BOA.tif

Product type

• Reflectance

  There is only one product type, i.e. the ImproPhed Bottom-of-Atmosphere Reflectance (IMP). The IMP product has the same specification as the BOA product (see Output Format), but spatial resolution was enhanced. The scale is 10000, and nodata value is -9999. IMP data contain multiple bands, which represent wavelengths, see metadata and following tables). All bands are provided at the same spatial resolution (see Parameter file).