[postgis-users] Open buffers or parallel lines

[Obe, Regina]

This might help

http://trac.osgeo.org/postgis/wiki/UsersWikiplpgsqlfunctions

 upgis_lineshift(centerline geometry, dist double precision)

Though its simplified in the sense it bases on start and end points of
the linestring to do the shift.

To do true shifting when you have very curvy lines or polygons - you'd
probably want to use Simon's approach.

http://www.spatialdbadvisor.com/postgis_tips_tricks/128/exploding-a-line
string-or-polygon-into-individual-vectors-in-postgis/

(hmm I though he had that wrapped more nicely in a function, but can't
find it).

Hope that helps,
Regina

 

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
Andreas Neumann
Sent: Tuesday, June 16, 2009 7:53 AM
To: PostGIS Users Discussion
Subject: {SPAM: 40} :[postgis-users] Open buffers or parallel lines

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.

Thanks for any hints,
Andreas


-- 
Andreas Neumann
http://www.carto.net/neumann/
http://www.svgopen.org/

_______________________________________________
postgis-users mailing list
postgis-users at postgis.refractions.net
http://postgis.refractions.net/mailman/listinfo/postgis-users
-----------------------------------------
The substance of this message, including any attachments, may be
confidential, legally privileged and/or exempt from disclosure
pursuant to Massachusetts law. It is intended
solely for the addressee. If you received this in error, please
contact the sender and delete the material from any computer.