Moritz Lennert wrote:
On 30/07/08 02:00, Adam Dershowitz wrote:
The problem that I am running into is that only the middle half or so
of the jpg is being rectified.
Do I have to set some region or something to get it all to work?
Yep, exactly.
AFAICT, the georectify tool calls i.rectify with the -c flag (line
1366 of gui/tcltk/gis.m/georect.tcl), which means "Use curr. region
settings in target location". So you need to set the correct location
in the target location.
I'm not sure I understand why this is so. It would seem to be more
intuitive to run without that flag and thus have i.rectify "determine
the smallest window which covers the image", because otherwise the
user has to identify target region extents manually...
Michael, any special reason for using -c ?
Maybe this could be made into an option ?
I went through exactly the same problem this week on my first attempts
on the georectify tool, and also wondered why it it chose those region
settings. I updated the wiki page last night to highlight the need for
a suitable region.
Also, sometimes I found that it crashed when the target region was
completely wrong because one of the intermediate stages was taking s=0
w=0 and I was working in UTM with typical values of 400000 and 7100000
and a resolution of 2 m. The resulting map must have been huge.
In the end I calculated the region that I would need manually and worked
out the resolution from the number of pixels in the scanned image. Does
i.rectify calculate these, or if not, is that something that could be
easily added?
Later
John
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