[GRASS-user] unexpected i.pansharpen results

[Eric Goddard]

I don't think that is the issue. I wasn't using serial processing, and I
was using the IHS method. The only place division occurs in the IHS method
is in the histmatch function, but that explicitly casts to float.


On Thu, Jan 31, 2013 at 1:52 PM, Markus Metz
<markus.metz.giswork at gmail.com>wrote:

> On Thu, Jan 31, 2013 at 7:06 PM, Michael Barton <Michael.Barton at asu.edu>
> wrote:
> >
> > i.pansharpen uses Python, not Bash. So it is not an integer math problem.
>
> But it calls r.mapcalc, e.g. in lines 151-153. If k is integer and not
> float, r.mapcalc will do integer division. Equivalent for lines 159,
> 162, 165. This could be fixed by casting the numerator to double with
> double().
>
> Markus M
>
> >
> > However, you might try changing your input maps to float or DCELL. See
> if that changes things.
> >
> > Michael
> > ______________________________
> > C. Michael Barton
> > Director, Center for Social Dynamics & Complexity
> > Professor of Anthropology, School of Human Evolution & Social Change
> > Arizona State University
> > Tempe, AZ  85287-2402
> > USA
> >
> > voice:  480-965-6262 (SHESC), 480-727-9746 (CSDC)
> > fax:          480-965-7671(SHESC), 480-727-0709 (CSDC)
> > www:  http://csdc.asu.edu, http://shesc.asu.edu
> > http://www.public.asu.edu/~cmbarton
> >
> > On Jan 31, 2013, at 2:11 AM, <grass-user-request at lists.osgeo.org>
> >  wrote:
> >
> > From: Yann Chemin <yann.chemin at gmail.com>
> > Subject: Re: [GRASS-user] unexpected i.pansharpen results
> > Date: January 31, 2013 2:11:33 AM MST
> > To: Hamish <hamish_b at yahoo.com>
> > Cc: GRASS user list <grass-user at lists.osgeo.org>
> >
> >
> > hmmm, yes that looks like an old friend to check...
> >
> >
> > On 31 January 2013 14:06, Hamish <hamish_b at yahoo.com> wrote:
> >>
> >> (sorry for the html,top posting)
> >>
> >> I wonder if the script is doing integer division when it should be
> doing floating point division?
> >>
> >>
> http://trac.osgeo.org/grass/browser/grass/trunk/scripts/i.pansharpen/i.pansharpen.py
> >>
> >>
> >> Hamish
> >>
> >> --- On Wed, 1/30/13, Eric Goddard <egoddard1010 at gmail.com> wrote:
> >>
> >>
> >> From: Eric Goddard <egoddard1010 at gmail.com>
> >> Subject: [GRASS-user] unexpected i.pansharpen results
> >> To: grass-user at lists.osgeo.org
> >> Date: Wednesday, January 30, 2013, 8:30 AM
> >>
> >>
> >> Hi all,
> >>
> >> I'm attempting to pansharpen some ikonos imagery using the i.pansharpen
> tool in Grass7 on windows 7 installed via OSGeo4W (r54756-478).  The range
> for the sharpened red, green, and blue outputs are 0-30, which seems
> suspicious given the 16bit range of the input bands. The command I used was:
> >>
> >> i.pansharpen.py "sharpen=ihs" "ms3=ik_mss.4 at eric" "ms2=ik_mss.3 at eric"
> "ms1=ik_mss.2 at eric" "pan=ik_pan at eric" "output_prefix=ik_ihs"
> >>
> >> The input bands are linked via r.external, would that matter?
> >>
> >> The output from my test area is below. Any assistance would be greatly
> appreciated.<image.png>
> >>
> >>
> >> Thanks,
> >> Eric
> >>
> >> -----Inline Attachment Follows-----
> >>
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> >
> >
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