[GRASS-dev] New GRASS addon i.sentinel.mask is now available (GSoC 2018 project)

Stefan Blumentrath Stefan.Blumentrath at nina.no
Thu Jun 14 04:08:19 PDT 2018

i.topo.corr performed quite well for us in the Norwegian mountains with minnaert method…
What options did you try in i.topo.corr?


From: Roberta Fagandini <robifagandini at gmail.com>
Sent: torsdag 14. juni 2018 13:01
To: Stefan Blumentrath <Stefan.Blumentrath at nina.no>
Cc: Moritz Lennert <mlennert at club.worldonline.be>; GRASS developers list <grass-dev at lists.osgeo.org>
Subject: Re: [GRASS-dev] New GRASS addon i.sentinel.mask is now available (GSoC 2018 project)

Hi Stefan!
Certainly applying the topographic correction could be very useful to avoid misclassification.
I did several tests with i.topo.corr but I always got strange results especially in areas with steeper terrain.
I also tested the topographic correction tool implemented in arcsi [0] but again the results were not satisfactory at all. This is why I have not further investigated this issue within my PhD research.

In order to remove misclassifications, e.g. due to topographic shadows, I implemented the shadow mask cleaning procedure. It intersects the rough shadow mask with the cloud mask that is shifted according to the sun position. In this way, all the areas identified as shadows without a corresponding cloud are removed from the final shadow mask.

I'm still very interested in investigating the topographic correction so if you have any suggestion please, let me know!!


[0] https://www.arcsi.remotesensing.info/index.html

2018-06-14 10:55 GMT+02:00 Stefan Blumentrath <Stefan.Blumentrath at nina.no<mailto:Stefan.Blumentrath at nina.no>>:
Hi Roberta,

What about topographic correction (i.topo.corr [1])?
Should that be run before as well?
I would assume it has some impact on shadow detection in steeper terrain…


1: https://grass.osgeo.org/grass74/manuals/i.topo.corr.html

From: grass-dev <grass-dev-bounces at lists.osgeo.org<mailto:grass-dev-bounces at lists.osgeo.org>> On Behalf Of Roberta Fagandini
Sent: torsdag 14. juni 2018 10:29
To: Moritz Lennert <mlennert at club.worldonline.be<mailto:mlennert at club.worldonline.be>>
Cc: GRASS developers list <grass-dev at lists.osgeo.org<mailto:grass-dev at lists.osgeo.org>>
Subject: Re: [GRASS-dev] New GRASS addon i.sentinel.mask is now available (GSoC 2018 project)

Hi Moritz!

2018-06-14 10:03 GMT+02:00 Moritz Lennert <mlennert at club.worldonline.be<mailto:mlennert at club.worldonline.be>>:
On 13/06/18 17:35, Roberta Fagandini wrote:
Hi all!
The first version of i.sentinel.mask is now available and can be installed from the official svn repository.
i.sentinel.mask is a module for cloud and shadow masks computation and it is the first step of my GSoC project.

Thank you, Roberta. Great job !

Thank you!

One question: ISTR that you mentioned that the input to this module has to be atmospherically corrected images, i.e. land surface reflectance. Is this true ? If yes, then this needs to be mentioned in the man page.

Yes, it's true! I'm going to add it.



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