[GRASS-dev] [GRASS GIS] #3443: Weird output of 'i.atcorr' in WorldView2 red channel (band 5)

#3443: Weird output of 'i.atcorr' in WorldView2 red channel (band 5)
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Reporter: ppina | Owner: grass-dev@…
     Type: defect | Status: new
Priority: normal | Milestone:
Component: Default | Version: 7.2.2
Keywords: i.atcorr, WorldView2 - red band | CPU: x86-32
Platform: MSWindows 7 |
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I performed the atmospheric correction with 6S algorithm (i.atcorr) in a
scene of WorldView2 satellite. It works nicely on the PAN band and on 7 of
its 8 multispectral bands. The bad one is the red channel (band 5) which
delivered weird results in some locations of the scene (sample details in
a file attached). I tested different parameters of the algorithm, used
radiance and reflectance images as input, but red band ouputs of i.atcorr
always looked weird. On the contrary, all atmospheric correction outputs
for all other bands showed to be 'normal'. Since this only happens with
this specific band, I wonder if there is not a bug in its processing or on
related filter functions.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/3443&gt;
GRASS GIS <https://grass.osgeo.org>

#3443: Weird output of 'i.atcorr' in WorldView2 red channel (band 5)
----------------------+---------------------------------------------
  Reporter: ppina | Owner: grass-dev@…
      Type: defect | Status: new
  Priority: normal | Milestone:
Component: Default | Version: 7.2.2
Resolution: | Keywords: i.atcorr, WorldView2 - red band
       CPU: x86-32 | Platform: MSWindows 7
----------------------+---------------------------------------------
Changes (by ppina):

* Attachment "iatcorr_WV2_MS5.pdf" added.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/3443&gt;
GRASS GIS <https://grass.osgeo.org>

#3443: Weird output of 'i.atcorr' in WorldView2 red channel (band 5)
----------------------+---------------------------------------------
  Reporter: ppina | Owner: grass-dev@…
      Type: defect | Status: new
  Priority: normal | Milestone:
Component: Default | Version: 7.2.2
Resolution: | Keywords: i.atcorr, WorldView2 - red band
       CPU: x86-32 | Platform: MSWindows 7
----------------------+---------------------------------------------

Comment (by neteler):

We ave implemented the filter functions provided here:

https://apollomapping.com/blog/new-documents-atmospheric-correction-
digitalglobe-satellites-2

I just converted them once more and the resulting curves are the same. For
the CSV files implemented, see
https://trac.osgeo.org/grass/browser/grass/branches/releasebranch_7_2/imagery/i.atcorr/sensors_csv

Question: You speak about band 5 = red. However, the filter functions are
ordered as this:

{{{
1 2 3 4 5 6 7 8 9
Pan Blue Green Red NIR1 Coastal Yellow Red Edge NIR2
}}}

i.e. the 5th band is NIR1. May that be the reason (wrong band number)?

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Ticket URL: <https://trac.osgeo.org/grass/ticket/3443#comment:1&gt;
GRASS GIS <https://grass.osgeo.org>

#3443: Weird output of 'i.atcorr' in WorldView2 red channel (band 5)
----------------------+---------------------------------------------
  Reporter: ppina | Owner: grass-dev@…
      Type: defect | Status: new
  Priority: normal | Milestone: 7.4.5
Component: Imagery | Version: 7.2.2
Resolution: | Keywords: i.atcorr, WorldView2 - red band
       CPU: x86-32 | Platform: MSWindows 7
----------------------+---------------------------------------------
Changes (by neteler):

* component: Default => Imagery
* milestone: 7.2.4 => 7.4.5

Comment:

Several stability fixes were applied (r73183, r73188 etc).
Does the problem persist in GRASS GIS 7.6.x or later?

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Ticket URL: <https://trac.osgeo.org/grass/ticket/3443#comment:3&gt;
GRASS GIS <https://grass.osgeo.org>