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On 16-12-2011 15:32, Jan Hartmann wrote:
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<font face="Times New Roman, Times, serif">Hi all,<br>
<br>
Is it possible to do a first order GCP-warp *without* shearing?
I have a rectangular scan with very imprecise control points,
and I want it georeferenced without any distortion. With a first
order gdalwarp I get back a map in the form of a parallellogram.
Is there a way to get back the original rectangular form? </font><font
face="Times New Roman, Times, serif">Control points will be way
off, of course, but I am interested in the original forms of the
mapped items.</font><br>
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<font face="Times New Roman, Times, serif"><br>
Jan,<br>
<br>
What you want is to apply a transformation called (at least on the
Matlab parlance) "Linear conformal" which an afine transform but
without the the shear terms. Mirone has it implemented and if your
image has the GCPS embedded the operation is really simple.<br>
<br>
Joaquim<br>
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