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 <[email protected]>: > Dear Hang, > > On Fri, Jul 29, 2016 at 7:38 AM, Do Thi Hang <[email protected]> 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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