Hi,
Thanks Regina and Strk for your ideas.
Yes, the single-sided buffers would probably solve my problem.
Any predictions on why this patch will make it into the Postgis trunk? I
assume it won't be possible for Postgis 1.4.0, but maybe for 1.4.1?
Another requirement I have is getting full buffers around linestrings
that would also offer the butt and square linecaps instead of just round
linecaps. I initially thought to get this simulated by setting
num_seg_quarter_circle to zero - but this doesn't work. It always
introduces at least one vertex for the linecaps.
Thanks,
Andreas
strk wrote:
On Tue, Jun 16, 2009 at 01:52:33PM +0200, Andreas Neumann wrote:
Hi all,
I am looking for either a "parallel line" feature or "open buffers around
a linestring element".
The idea is to visualize a waste-water system where in large map scales
the actual diameter of the waste-water pipes (canalization). The linecaps
shouldn't be stroked, but the parallel offset to the centerline should be
drawn.
Are there any tricks how this can be done in Postgis? I see that there is
st_buffer, but there is no option to get an open buffer or parallel lines.
See if what's currently referred to "Single-Sided-Buffer" and probably
to become "Offset Curve" is what you're looking for.
http://trac.osgeo.org/geos/ticket/215
--strk;
Free GIS & Flash consultant/developer () ASCII Ribbon Campaign
http://foo.keybit.net/~strk/services.html /\ Keep it simple!
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