| Biophysical Processor Description | |
The Biophysical Processor LANDSAT8 is optimized to use a LANDSAT8 product as input instead of a Sentinel2 product, however it is only capable of computing LAI, FAPAR and FVC indexes.
LANDSAT8 Collection 2 does not provide the zenith and azimuth angles for L2 products. To use the Biophysical operator on these products, the 4 bands must be added first.
Steps:
1. Download both the Level 1 and Level 2 products for the same image.
2. Copy the four total sun and view azimuth files from Level 1 folder (the four TIFs ending in _SZA.tif, _SAA.tif, _VAA.tif, _VZA.tif) to Level 2 folder.
3. Copy the information for these four layers in the Level 1 metadata file (ending in ?_MTL.txt?), and paste it into the Level 2 metadata file. The four new bands will be loaded in SNAP as vaa, vza, saa, and sza.
4. The DN values of the angles are scaled by 100, so we need to apply the Band Maths operator to multiply them by 0.01. The new 4 bands will be:
Name: Used to select the spectral source product. The source product shall be a LANDSAT8 product. Use the ... button to open a data product currently not opened in the application. The algorithm is calibrated for top-of-canopy reflectances and depends on the acquisition geometry, so it requires slope-effect corrected reflectances to give optimal results
Name: Used to specify the name of the target product.
Save to: Used to specify whether the target product should be saved to the file system. The combo box presents a list of file formats.
Open in SNAP: Used to specify whether the target product should be opened in the application. When the target product is not saved, it is opened automatically.
Compute LAI:
Enable/Disable the computation of LAI (Leaf Area Index) in the output product
Compute FAPAR:
Enable/Disable the computation of FAPAR (Fraction of Absorbed Photosynthetically Active Radiation) in the output product
Compute FVC:
Enable/Disable the computation of FVC (Fraction of Vegetation Cover) in the output product