Sentinel 2 - L2A "Cirrus Correction" and the "Terrain Correction"


#1

Hi

I performed the convertion in L2A 10m (Thanks to ChristianSeverin for his Workaround :wink:) and it seems to work!

I read in the PDF manual “sen2cor-sum-2.0” that the “Cirrus Correction” and the “Terrain Correction” are both optional;

How can I perform these corrections?

I use Sen2Cor in SNAP under Windows 10 64 bit

Thanks in advance!

Roberto


#2

Hi,
I suppose that you have to set the proper values in your config file L2A_GIPP.xml

Line 8: A folder to download the SRTM terrain data
Line 95: A 1 for cirrus correction
Line 96: A 1 for BRDF correction


#3

Thanks for the answer @ralf,

I modified the file L2A_GIPP.xml

DEM_Directory>DEM</DEM_Directory>
Cirrus_Correction>1</Cirrus_Correction>
BRDF_Correction>1</BRDF_Correction>

I performed the correction with Cirrus and Terrain Correction (RES 10m),

The script seem to work, it downloads a DEM in my folder, unzip it and all my granules are processed but…

the outputs seem the same that I had with the normal L2A conversion (without cirrus and terrain)

any idea??

Thanks


#4

Hi,

the terrain correction works in my case, although the DEM resolution (~90m) - which is used automatically - seems to be not optimal for the 10m processing.

For all the other options i’ve got the same problem!!! no matter which option i choose via the L2A_GIPP.xml, the output is unchanged.

However I found an explanation in the Sentinel-2 MSI – Level 2A Products Algorithm Theoretical Basis Document why 2 options are not working:

  • the “issue of cirrus removal is left open” for Sentinel-2 data
  • the Haze removal is also disabled Sentinel-2, if i got it right…

#5

has anyone an idea how to change the slope-criterion > 6° => perform topographic correction??


#7

Hi,
Have you figured this out?

I got the same problem, I run with sen2cor 2.1.1
DEM works, but both brdf and cirrus correction are not working, the output is unchanged at all.

Many thanks!


#8

unfortunately not…sorry!


#9

Hello everyone,

topographic correction does not work in my case…
I change the L2A_GIPP.xml as follows:
DEM_Directory > DEM

Also, i tried to do it using my own DEM in GeoTiff format (.tif, geographic WGS 84) and Global.

So, i changed the dem directory:
DEM_Directory > DemGreece

But the result is unchanged at all…

Am i doing something wrong; or that’s it because the terrain is rugged; I think that i could recognize some difference if existed.

Cirrus correction does not work for sure.

@HaiyanHuang @michi HELP :sweat:


#10

You meant no difference in the output no matter you with topographic
correction or without topographic correction?

I have no idea…

I do not have my own DEM files, what I do is to set the line 10 in
L2A_GIPP.xml to <DEM_Directory>dem/srtm</DEM_Directory>, it downloads DEM
automatically according to the L1C megadata.

BWT, I run the linux version 2.1.1


#11

I am trying to perform the topographic (slope) and cirrus correction of L1C images from Sentinel 2A, using the SNAP with Sen2Cor.

However, it is very difficult to find a user manual for these two operations (I have also reviewed this STEP forum, the L2A-SUM]%20S2-PDGS-MPC-L2A-SUM%20[2.3.0].pdf document, the software help, etc.). I was wondering if you have any additional information about how to do this (publication, video, etc.).


#12

@r.bianconi,I had the same problem. I wonder if you had solved this problem now?
I also modified the file L2A_GIPP.xml,
DEM_Directory>DEM
Cirrus_Correction>True
BRDF_Correction>1
I also performed the correction with Cirrus and Terrain Correction. But the results are without eliminating the topographic effects.