[GRASSLIST:7472] Re: ERDAS Atcor vs. i.atcor

[Martin Wegmann]

Hello, 

Maciek referred me to Wolfgang Lück who did a comparison between MODTRAN and 
6S. He will publish the results end of the year. However he received the 
permission by Vermote to rewrite the Fortran code of 6S to C but not yet to 
release it under the GPL. 

please see this quote of his response for further informations:

"Thank you for your interest in i.atcor (6S). I am busy validating and 
comparing results from this module with Atcor 2 & 3 as implemented in PCI. We 
intend to improve it so that atmospheric products from MSG can be integrated 
to define correction models more accurately. We also intend to improve the 
HOT model for relative visibility extraction with a possible combination of 
TC4 and HOT taking differences for land cover types (i.e water is problematic 
with HOT) into account. I do not expect our implementations to be quite as 
good as Richters models because we are no experts in atmospheric physics. I 
hope to publish my thesis end of the year and will thereby then present a 
quantitative comparison of the two models."
(wolfluck_AT_mweb.co.za)

regards, Martin


On Friday 01 July 2005 17:36, Jonathan Greenberg wrote:
> Martin:
>
>     I'd recommend also posting this question to the Remote Sensing listserv
> I moderate at UC Davis: http://www.cstars.ucdavis.edu/starserv .  We have a
> lot of people use ATCOR and other image calibration programs on this
> listserv!  Please post your responses if and when you get them to this
> list, I'm interested in hearing what you find out!
>
> --j
>
>
> On 7/1/05 5:02 AM, "Grit Schuster"
>
> <grit.schuster at geographie.uni-freiburg.de> wrote:
> > Hi Martin,
> >
> > I can't tell you anything about the goodness or performance.
> >
> > I just know that the moduls use different algorithms.
> > Atcor for ERDAS uses MODTRAN. The Grass module uses 6S.
> >
> >
> > As far as I know, MODTRAN is quite widely used.
> >
> > The method to use for an atmospheric correction depends on
> > different factors:
> > on the kind of the atmospheric input data, the sensor, the spectral
> > bands you want to correct and of course on the purpose of your data
> > analyses.
> >
> > An interesting document about the atmospheric correction of ASTER data
> > is provided by the NASA
> > http://eospso.gsfc.nasa.gov/eos_homepage/for_scientists/atbd/docs/ASTER/a
> >tbd-a st-09t.pdf.
> > I think this gives a good overview about the relevance of the different
> > parameters used for atmospheric corrections and their influence on the
> > accuracy of the results.
> >
> > You could post this topic to the Applied GIS & RS mailing list
> > (http://www.matox.com/agisrs/).
> >
> > If you'll find out something, I would quite interested in it :-)
> >
> > Sorry that I can't tell you more. Hope this helps a bit!
> >
> > Grit
> >
> > Martin Wegmann wrote:
> >> Hello,
> >>
> >> I wonder if somebody can judge the goodness of performance for the
> >> output of ERDAS Atcor (http://www.geosystems.de/atcor/) vs. GRASS
> >> i.atcor (http://www.cs.sun.ac.za/~caz/6S/i.atcorr.html). Are their
> >> methods comparable at all? I am not experienced in atmospheric
> >> correction and hence all the algorithm are rather meaningless to me.
> >>
> >> Any links, papers, comparisons etc. are welcome, thanks in advance,
> >> Martin

-- 
Martin Wegmann

DLR - German Aerospace Center
German Remote Sensing Data Center
@
Dept.of Geography
Remote Sensing and Biodiversity Unit
University of Wuerzburg
Am Hubland
97074 Würzburg

phone: +49-(0)931 - 888 4797
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