[GRASS-user] color anomalies after orthorectification
st_kiefer at web.de
Thu Feb 20 16:25:31 PST 2014
OK, I found a workaround.
with r.mapcalc I identify all values lt 1 and gt 254 and set them to 1
resp. 254. Actually not a nice way but the result is good enough for the
Anyway, I still would be thankfull for an explanation of the phenomenon,
moreover a better solution to avoid that behaviour.
Am 21.02.2014 00:26, schrieb Stefan Kiefer:
> 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).
> 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
> grass-user mailing list
> grass-user at lists.osgeo.org
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