[GRASS-user] i.atcorr returns all NULL values for AVNIR-2 band 2, 3

[Do Thi Hang]

Dear Mr Markus,

Yes, the inputs were converted to TOA radiance by using formular: Rad =
DN*Gain + Offset, range of 4 bands:

  band 1: min = 42.336  max = 149.94 (Comments: b1 * 0.588
  band 2: min = 25.212  max = 146.115 (Comments: b2 * 0.573)
  band 3: min = 15.562  max = 128.01 (Comments: b3 * 0.502)
  band 4: min = 11.14  max = 124.768 (Comments: b4 * 0.557)

When I try with input which presents TOA reflectance and use "i.atcorr -r",
it also returns all NULL values for band 2,3.

Attachments are orginal band 2 (b2) and TOA radiance of band 2 (b2_rad).

Thank you so much for your support.​
 b2_rad
<https://drive.google.com/file/d/0B7hMJ463uflaLTRxWFM5blpkNG8/view?usp=drive_web>
​​
 b2
<https://drive.google.com/file/d/0B7hMJ463uflaWVhNQXZMTWJYSXc/view?usp=drive_web>
​


Yours sincerely,
Hang


---  --- --- ---
Do Thi Hang (MSc candidate)
GIS Laboratory
Graduate school for Creative Cities
Osaka City University
Tel. +81-90-8385-6238

2016-08-04 0:49 GMT+09:00 Markus Neteler <neteler at osgeo.org>:

> Dear Hang,
>
> On Fri, Jul 29, 2016 at 7:38 AM, Do Thi Hang <dohanghumg at gmail.com> wrote:
> > Dear all,
> >
> > I am trying to use i.atcorr in GRASS GIS 7 with AVNIR-2 data in Japan, it
> > works well for band 1,4 but returns all NULL values for band 2,3. Maybe
> the
> > problem is because of Sensor band parameter (the last one in 6S
> parameters,
> > the values are 81, 82. 83, 84 respectively band 1, 2, 3, 4): For all 4
> > bands, I change the parameter from 81 to 84, it returns all NULL values
> when
> > the parameter is 82 or 83; real/integer values when the parameter is 81
> or
> > 84.
>
> A question: are your AVNIR-2 input data representing radiance at
> top-of-atmosphere (TOA)?
>
> > Below is list of 6S parameters for band 2:
> >
> > 11                                         # geometrical conditions =
> avnir
> > 2 15 3.00 135.657 34.282       # month day hh.ddd long lat
> > 1                                           # atmospheric mode = tropical
> > 1                                           # aerosols model =
> continental
> > 11                                         # visibility (km)
> > -0.300                                   # mean target elevation above
> sea
> > level = 300 m
> > -1000                                    # sensor height = on board
> > 82                                         # 2th band of avnir
> >
> > Could anybody help me to solve this problem? Thank you very much.
>
> While I haven't worked with AVNIR-2 yet, I don't see any obvious
> errors in the file. Not sure about "tropical" for Osaka but it should
> deliver some result anyway.
> However, in the first place let's check the input data.
>
> Can you post the range of each channel here? (r.info output contains it).
>
> Best,
> Markus
>
> --
> Markus Neteler
> http://www.mundialis.de - free data with free software
> http://grass.osgeo.org
> http://courses.neteler.org/blog
>
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