On Thursday 22 January 2004 16:18, [EMAIL PROTECTED] ( Marc) (A.) 
(Lehmann ) wrote:
>On Thu, Jan 22, 2004 at 12:43:18PM -0700, Steve Strobel 
>> I tried using the perspective transform to adjust the corners of
>> the image so the section lines would be horizontal and vertical.
>That's actually correctly doing what the perspective transform is
> doing (try to imagine a plane with rectangles on it, in an angle
> towards you).
>From what you are writing, I'd say he shearing transform is
> *exactly* what you need, so what kind of problems are you facing
> when using a shear transform?

You may also be trying to undo the spherical component of the mapping.  
USGS maps, and most maps in general are on a spherical plane usually, 
sometimes on a modification of the mercator projection.  This may be 
something that the gimp coders could add, a 'de-sphericalizer'.  Make 
the user put in the 1/xxxxxx ratio as shown on the map and use that 
to calculate what to do.

Cheers, Gene
"There are four boxes to be used in defense of liberty: soap,
ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
99.22% setiathome rank, not too shabby for a WV hillbilly
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Copyright 2004 by Maurice Eugene Heskett, all rights reserved.
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