[GRASS-user] [GRASS-dev] Added i.landsat8.swlst in grass-addons

[Blumentrath, Stefan]

Hei again,

Yesterday I updated i.landsat8.qc (https://grass.osgeo.org/grass70/manuals/addons/i.landsat8.qc.html).
Main change is that the module is now more generalized, a bit faster (but this was never heavy computation anyway) and simplified.

In short, now the module only produces a file with reclassification rules for r.reclass. When building the rules, now all possible integer values for the 16bit binary string of the Landsat8 QA band are being evaluated (and not only the integer values of an input QA band as before). Thus the reclass-rules can be applied to any scene. As a consequence, no input and output maps are required and the p- and i-flag were removed.

I am not sure if the reclassification should be re-included or not. For the time being I excluded this step, as it is no big deal to run r.reclass afterwards, and i.landsat8.qc is kept focused on one task...
But if it is considered to be more appropriate if the module also does the reclassification, I can happily add it again...

Cheers
Stefan 

-----Original Message-----
From: grass-user [mailto:grass-user-bounces at lists.osgeo.org] On Behalf Of Blumentrath, Stefan
Sent: 14. mai 2016 23:21
To: Nikos Alexandris <nikos.alexandris at unige.ch>
Cc: grass-user grass-user (grass-user at lists.osgeo.org) <grass-user at lists.osgeo.org>
Subject: Re: [GRASS-user] [GRASS-dev] Added i.landsat8.swlst in grass-addons

Hei Nikos (and others),

Actually, on a second thought, I am considering to change the module significantly.

Maybe better to just generate a file with reclassification rules for all possible combination of bitpattern?
That would simplify the module (only the filter criteria are required as input), and the resulting r.reclass rules can be applied to any landsat scene...
So they can be generated once and then reused.

That would be more efficient if several scenes should be processed with the same procedure. However users would have to run r.reclass themselfs in a next step... But that is probably more in line with the modular concept of GRASS...

What do you think /prefer?

Cheers,
Stefan
________________________________________
Von: Nikos Alexandris [nikos.alexandris at unige.ch]
Gesendet: Samstag, 14. Mai 2016 16:49
An: Blumentrath, Stefan
Cc: grass-user grass-user (grass-user at lists.osgeo.org); grass-dev at lists.osgeo.org
Betreff: Re: [GRASS-user] [GRASS-dev] Added i.landsat8.swlst in grass-addons

SuperGreat Stefan!

Long standing idea... finally realised. Danke, Nikos



* Blumentrath, Stefan <Stefan.Blumentrath at nina.no> [2016-05-11 10:22:48 +0000]:

>Hi again,
>
>I just pushed a new addon ("i.landsat8.qc") to addons svn.
>i.landsat8.qc reclassifies Landsat8 QA band according to a user defined filter for bit pattern representing unacceptable quality pixels. It implements basically the procedure mentioned below...
>
>Any feedback is welcome...
>
>Kind regards,
>Stefan
>
>-----Original Message-----
>From: grass-dev [mailto:grass-dev-bounces at lists.osgeo.org] On Behalf Of Blumentrath, Stefan
>Sent: 10. mai 2016 09:57
>To: Nikos Alexandris <nikos.alexandris at unige.ch>; Vaclav Petras <wenzeslaus at gmail.com>
>Cc: grass-dev at lists.osgeo.org
>Subject: Re: [GRASS-dev] Added i.landsat8.swlst in grass-addons
>
>Another issue I came across it that currently, a possibly existing user mask will be simply overwritten, while it might be more friendly to backup the user mask before and restore it after the module finished... However, in order to simplify the module a bit, an option might be to move the masking part out of the module, and probably write something like this: https://grass.osgeo.org/grass70/manuals/i.modis.qc.html for Landsat, if that does not exist yet(?). Seems you thought about it already?
>Based on Markus tutorial (http://courses.neteler.org/processing-landsat8-data-in-grass-gis-7/#Applying_the_Landsat_8_Quality_Assessment_%28QA%29_Band) and the info here http://landsat.usgs.gov/qualityband.php that should be a quite doable job. If no landsat bitpattern module exists I might be able to volunteer...
>The idea would be something like this: extract raster values from QA band, loop over those values, compare the bit pattern representation of the integer values with acceptable bit patterns defined by the user, add the result of the comparison to r.reclass rules, and finally reclassify the QA band...
_______________________________________________
grass-user mailing list
grass-user at lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user