Brazilian Agricultural Research Corporation (EMBRAPA)
Question
Asked 1st Feb, 2015
Is there a way to implement MODIS-AOD-Data to perform a spatially variable atmospheric correction using GrassGIS and its 6S algorithm?
I want to atmospherically correct Landsat 8 images with GrassGIS using Aerosol Optical Depth, obtained from MODIS-Data.
Most recent answer
Hi, Steven! It looks like you have this option when you use GRASS-plugin ebedded in Quantum GIS (version 2.0 or higher). The 'i.atcorr" command that you find there in the Processing toolbox has two input parameters, where you can insert a visibility raster map and an altitude raster map to perform the atmospheric correction. Well, I have never used this plugin to perform atmospheric corrections, so I can't tell you if it works well or not... But I thinks it's worth it to try it out.
There are some problem you may have to deal with:
1.You will have to activate GRASS plugin in QGIS before using it, setting the current directory of GRASS plugin in the "Processing > Options" menu.
2. You have to select the "Advanced interface" option under the Processing Toolbox, at the right of canvas. The default is the "simplified interface" that does not contain the main tools of the Toolbox.
3. You will have to convert your MODIS AOD values to visibility values. In order to do that, I suggest you to take a look in a paper I wrote with other colleagues:
I think there are other methods to convert AOD to visibility, but this method works well in the data we have processed.
Good luck!
All Answers (5)
Solar Consulting Services
From the description at http://grass.osgeo.org/grass64/manuals/i.atcorr.html you can enter a value for AOD at 550 nm, which you can get from MODIS. It does not seem you can make that value variable if you consider a large area, though.
Brazilian Agricultural Research Corporation (EMBRAPA)
Hi, Steven! It looks like you have this option when you use GRASS-plugin ebedded in Quantum GIS (version 2.0 or higher). The 'i.atcorr" command that you find there in the Processing toolbox has two input parameters, where you can insert a visibility raster map and an altitude raster map to perform the atmospheric correction. Well, I have never used this plugin to perform atmospheric corrections, so I can't tell you if it works well or not... But I thinks it's worth it to try it out.
There are some problem you may have to deal with:
1.You will have to activate GRASS plugin in QGIS before using it, setting the current directory of GRASS plugin in the "Processing > Options" menu.
2. You have to select the "Advanced interface" option under the Processing Toolbox, at the right of canvas. The default is the "simplified interface" that does not contain the main tools of the Toolbox.
3. You will have to convert your MODIS AOD values to visibility values. In order to do that, I suggest you to take a look in a paper I wrote with other colleagues:
I think there are other methods to convert AOD to visibility, but this method works well in the data we have processed.
Good luck!
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