Hi,
as Markus wrote there are no overshoots with bilinear method.
Nevertheless I agree with keeping cubic and forcing the range.
Particular because I only rely on greyscale aerial photographs, so it
doesent matter if its more or less black or white. Especially when
humans can't distinguish more than 130 shades of grey. An apropriate
rectification is more desirable.
Thanks again for the support and the discussion.
best regards
Stefan
Am 21.02.2014 13:57, schrieb Markus Metz:
On Fri, Feb 21, 2014 at 9:27 AM, . . <[email protected]> wrote:
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 would leave it as it is. Bicubic gives nice results, but these
overshoots must be taken care of. Your method of forcing values back
to the range of 1,254 seems appropriate to me for handling resampling
overshoots.
Markus M
I will try this when I'm back in office and give a feedback of my
experiences then.
best regards
Stefan
Markus Metz <[email protected]> hat am 21. Februar 2014 um
08:05 geschrieben:
On Fri, Feb 21, 2014 at 12:26 AM, Stefan Kiefer <[email protected]> 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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