I run Sen2Cor L2A_Process.bat
to produce L2A products of Sentinel-2 , and it works. But the result reflectance value is so large. When I calculate NDVI by gdal_calc.py after resample B8 to 20m, the result NDVI values range from 0 to ~800.
gdal_calc.py -A B8_20m.jp2 -B B4_20m.jp2 --format=GTiff --outfile=NDVI.tif --calc="(B - A)/(B + A)"
When I change the script to below, I got reasonable NDVI values of [0, 1]
gdal_calc.py -A B8_20m.jp2 -B B4_20m.jp2 --format=GTiff --outfile=NDVI.tif --calc="(B /10000.0- A/10000.0)/(B/10000.0 + A/10000.0)"
But @ABraun in sen2cor-reflectance-values/3805 post that
The Sen2Cor result data is stored as integer but SNAP interprets it as floats (value divided by 10.000)
I am wondering why it is 10.000 but not 10000.0?
Very grateful for the help!