Opened 8 years ago

Last modified 5 years ago

#2545 new defect

i.atcorr RapidEye band1

Reported by: chrisraa Owned by: grass-dev@…
Priority: normal Milestone: 7.2.4
Component: Imagery Version: svn-releasebranch72
Keywords: i.atcorr Cc:
CPU: Unspecified Platform: MSWindows 7

Description

Dear grass gis team, actually I am working with several RapidEye (product Type L3A) acquisitions, in order to pre-process them for classification. It occurred to me that in some cases i.atcorr creates a results for the first band (blue), which seems to be “biased”. I applied i.atcorr on different machines and used different versions of Grass, but the issue is persistent.

Grass versions I tried on a Windows7 Professional, 64-bit system: 6.4.4, 7.0.0beta4 and 7.1svn

Input text file values I used:

13

5 25 12.8 52.09413 -10.22328

2

2

0

0.161

-0.253824

-1000

88

For the input imagery and its range a used the min and max values of the radiance image. As input altitude raster map a 5m DEM was used and for rescale output the range 0,1.

Please let me know if you need further information! Many thanks in advance!! Christoph

Attachments (3)

i.atcorr_Rapid_Eye_band1.PNG (100.3 KB ) - added by chrisraa 8 years ago.
example_i.atcorr_RapidEye_band1
rapideye.csv (6.8 KB ) - added by craab 6 years ago.
rapideye_filterf.diff (24.5 KB ) - added by craab 6 years ago.

Download all attachments as: .zip

Change History (16)

by chrisraa, 8 years ago

example_i.atcorr_RapidEye_band1

comment:1 by martinl, 7 years ago

Milestone: 6.4.5

Ticket retargeted after milestone closed

comment:2 by martinl, 7 years ago

Milestone: 6.4.6

comment:3 by neteler, 7 years ago

I think I identified the issue:

The filter function values for RapidEye do not have the needed precision (only 2 digits!):

compare:

https://trac.osgeo.org/grass/browser/grass/trunk/imagery/i.atcorr/sensors_csv/rapideye.csv

to e.g.

https://trac.osgeo.org/grass/browser/grass/trunk/imagery/i.atcorr/sensors_csv/geoeye1.csv

We need a higher resolution rapideye.csv

by craab, 6 years ago

Attachment: rapideye.csv added

by craab, 6 years ago

Attachment: rapideye_filterf.diff added

comment:4 by craab, 6 years ago

I found more precise values here:

https://resa.planet.com/files/2014-06/Spectral_Response_Curves.pdf

I updated the rapideye.csv file, as well as the iwave.cpp file according the provided filter curve data.
Please see the provided diff file.

Best, Christoph

in reply to:  4 comment:5 by neteler, 6 years ago

Milestone: 6.4.67.2.1
Version: unspecifiedsvn-releasebranch72

Replying to craab:

I found more precise values here:

https://resa.planet.com/files/2014-06/Spectral_Response_Curves.pdf

I updated the rapideye.csv file, as well as the iwave.cpp file according the provided filter curve data.
Please see the provided diff file.

This is great, thanks. Uploaded to trunk for testing in r70078.

Later to be backported once it is known to work ok (please report here).

comment:6 by craab, 6 years ago

I tested the adjustment and it works, but it is not part of the solution either. However, I traced back the problem to the optical thickness value, which was to high:

(https://www.rese-apps.com/pdf/atcor3_manual.pdf , page 19)

"If the visibility is assumed too low (optical thickness too high) the path radiance becomes high, and this may cause a physically unreasonable negative surface refectance. Therefore, dark surfaces of low refectance, and correspondingly low radiance c0+c1DN, are especially sensitive in this respect."

I guess the ticket can be closed and I will try to put together a paragraph for the manual.

comment:7 by martinl, 6 years ago

Milestone: 7.2.17.2.2

in reply to:  6 comment:8 by neteler, 6 years ago

Replying to craab:

I tested the adjustment and it works,

I have backported it in r71053.

but it is not part of the solution either. However, I traced back the problem to the optical thickness value, which was to high:

(https://www.rese-apps.com/pdf/atcor3_manual.pdf , page 19)

"If the visibility is assumed too low (optical thickness too high) the path radiance becomes high, and this may cause a physically unreasonable negative surface refectance. Therefore, dark surfaces of low refectance, and correspondingly low radiance c0+c1DN, are especially sensitive in this respect."

I guess the ticket can be closed and I will try to put together a paragraph for the manual.

Please consider to provide a manual text snippet, even here or as a patch to the HTML page.

comment:9 by neteler, 5 years ago

Milestone: 7.2.27.2.3

Ticket retargeted after milestone closed

comment:10 by martinl, 5 years ago

What is status of this issue?

in reply to:  10 comment:11 by neteler, 5 years ago

Replying to martinl:

What is status of this issue?

The promised text snippet for the manual did not arrive yet...

comment:12 by martinl, 5 years ago

Milestone: 7.2.3

Ticket retargeted after milestone closed

comment:13 by martinl, 5 years ago

Milestone: 7.2.4
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