6S atmospheric correction

[chuoimotcu]

Hi, 

 

I am newbie of atmospheric correction. 

I want to apply 6S model to new sensor such as Landsat 8, however, 6S doest not support yet. 

 

In sensor options, there is a user define part to declare Landsat 8 bands, but I do not how to use it. 

 

Does anyone can help me? 

 

thank you in advance.

Cheers,

[Lurker]

what software you use?

 

some guide :

http://www.gisagmaps.com/landsat-8-atco-guide/

[chuoimotcu]

Thank Lurker, 

I wanna use 6S model (Second Simulation of a Satellite Signal in the Solar Spectrum)

 

cheers,

[winash12]

 

what software you use?

 

some guide :

http://www.gisagmaps.com/landsat-8-atco-guide/

Hello,

           I am looking to do the same thing - apply atmospheric correction to my landsat 8 images. That website requires a paid login. Are there any free URLs available ?

Regards. 

[mamadouba]

6S is the primary radiative transfer model used to correct Landsat 4, 5, and 7 in LEDAPS. The 6S sensor models have not been updated to include the OLI or TIR bands for Landsat-8. However, there is a much easier method to obtaining surface reflectance and other scientific datasets for all Landsat missions, including Landsat-8. If you have a USGS Earth Explorer account, you can now order Landsat Climate Data Records (CDRs) directly which include surface reflectance, multiple vegetation indices, and the cloud/shadow/water/snow/ice mask from CFmask. You can also go directly to USGS ESPA website and order bulk Landsat CDR products. I believe up to 5000 scenes at a time. If you only require the scientific products, let USGS do all the major processing for you, plus you ensure that the same algorithm, parameters, and techniques are applied to the record so the data are standardized.

[winash12]

Thanks for your response. I would like to do this programmatically on my own i.e. download landsat 8 images and then programmatically apply atmospheric correction as this needs to be done on a frequent basis. So any documentation in this regard would be appreciated.

[mamadouba]

I understand.  Just be aware that if you are new to atmospheric correction, you will need to become familiar with the atmospheric and aerosol modeling parameters required by 6S.  For example, LEDAPS, which uses 6S, automatically estimates atmospheric conditions using a variety of daily archived ancillary data such as ozone and water vapor.  It also calculates the Aerosol Optical Thickness using scene based techniques.  Your results can be be erroneous if you are unable to provide these details to the 6S model.  

 

As for using 6S to correct for Landsat-8 data, you will need to select the Spectral Conditions option, "user-defined filter function."  This option requires start and end band wavelengths in microns, and the filter function values in increments of 0.0025 microns.  You can download the band specific relative spectral response functions for OLI from the Landsat website:

http://landsat.gsfc.nasa.gov/?p=5779.  

 

The spreadsheet developed by Ball Aerospace is here: 

http://landsat.gsfc.nasa.gov/wp-content/uploads/2014/09/Ball_BA_RSR.v1.2.xlsx

 

I'm assuming that you downloaded the 6S source code and user manuals from here: 

http://6s.ltdri.org/

 

I'm also assuming that you compiled the Fortran code into an executable binary.

 

To start, use the web-based version of 6S as a practical exercise in developing the input/output files for 6S.  You can then develop your own subroutines to parse the necessary metadata parameters from the Landsat MTL text file if you are planning on running batch processes programmatically (i.e., month/day of collection, viewing geometries, etc.) 

 

If you are familiar with Python, I highly recommend using this program developed by Wilson, R., called Py6s.  Py6s provides an API that "allows you to run many 6S simulations using a simple Python syntax, rather than dealing with the rather cryptic 6S input and output files. As well as generally making it easier to use 6S, Py6S adds some new features."  It's a great contribution to the community:

 

https://py6s.readthedocs.org/en/latest/introduction.html

 

Good luck.