Hi,
I am trying to calculate Sentinel-2 based spectral vegetation indices using two different approaches:
- Using a graph builder in SNAP.
- Creating it myself in R using L2 data that I downloaded from Copernicus Open Access Hub.
Here the problem is in the different values that I am getting.
In both of the cases the input data is L2A data downloaded straight from Sentinel-2 data hub but the index values are very different. Even the band values are different. The exact band value for B2 lets say would be different when it goes through SNAP.
I acknowledge the scaling factor of 10000 when the band reflectance values are calculated by myself.
I suspect it is because of the harmonization that happened after 2022 (my current data comes from 2024). However, I haven’t done anything for harmonization in SNAP either. I haven’t even provided any command for scaling the DN values. Still it returns the final band and index values in a perfect range.
I just want to know how its working and would like to see same results when I am doing it myself.
Any help would be highly appreciated.
Thanks in advance.
Rajeev
