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

[Markus Neteler]

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