rectify a scanned map
coopl at BCC.ORST.EDU
Fri Nov 19 15:42:29 EST 1993
I have scanned a map of the western US (lambert projection)
and want to register it as lat-long.
i.rectify does a poor job. It looks OK at the edges or in the middle
points but not both. The error is as much as 200 miles. The number of
points I use does not affect error very much. Is the problem
because i.rectify expects a more planar image (such
as a satellite image)? Do I need a way to convert the lambert
(conical) projection into a cylindrical one? Grass 4.0 does not seem to
have a module to convert coordinate systems in this way. How do we
get a more accurate registration/rectification?
This must be a problem solved every day somewhere, but we are stumped for
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