Extract the exterior ring of your political boundaries, so you're
working with linestrings.
Then see which rivers have start and end segments very close to those
boundaries. Should be a start.
P
On Mar 11, 2009, at 8:49 AM, [email protected] wrote:
Greetings,
Firstly, PostGIS continues to rock! Thanks so much for this
software...
My question is that I have a rivers linestring table and a political
boundaries table (US counties) polygon. I am wishing to extract the
portion of the river geometry that lies along a county border. Of
course, these two layers don't have the same individual point
precision, so I suspect some buffering, simplification is
necessary. I am not seeking anything exact, but something like if
the river and a county border are within a few hundred meters of
each other for some distance along the river and county border.
I can't seem to figure out which functions could accomplish this
task, or if it is possible. Currently, I have no issue finding
points of intersection, so perhaps that is part of the solution that
is staring me in the face :)
Thanks!
daryl
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Paul Ramsey
[email protected]
+1 250 885 0632
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