[GRASS-user] color anomalies after orthorectification

[. .]

Hi Markus,
thanks for that hint, that might be the solution. As I must confess I did not
only try any of the other methods, believing cubic would yield the best results
because the scans are from an area with high energy of relief.
I will try this when I'm back in office and give a feedback of my experiences
then.

best regards

Stefan

> Markus Metz <markus.metz.giswork at gmail.com> hat am 21. Februar 2014 um 08:05
> geschrieben:
>
>
> On Fri, Feb 21, 2014 at 12:26 AM, Stefan Kiefer <st_kiefer at web.de> wrote:
> > Hi,
> > I tried to orthorectify aerial photographs. That worked fine by now, until
> > i got scans wich appear to be darker as before. At least this is the first
> > observation I made. The effect occured with that scans is, that after
> > rectification some of the dark areas become white (or rather null, querying
> > that cells result in -0.722622310236638).
>
> This should only happen with method=cubic or method=cubic_f. The other
> resampling methods nearest,bilinear,bilinear_f should not produce
> these resampling overshoots.
>
> Markus M
>
>
> > Has anyone had similar experiences when rectifying aerial photographs. And
> > hopefully a hint how to avoid this damages. I suspect that the
> > orthorectified images become double precision whereas the imported scans are
> > integer...
> >
> > best regards
> >
> > Stefan
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> > grass-user at lists.osgeo.org
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