[postgis-users] Which postGIS functions to use?

[Paragon Corporation]

I don't quite understand your question.

Are you trying to get the length of the intersection of the 2?  So that part
of the network component that falls within the quay?

In that case it would be something of the form

SELECT ST_Length(ST_Intersection(netcomponent.the_geom, quay.the_geom)) 

Which assumes your netcomponent is defined as a LINESTRING (you can use
ST_MakeLine
http://postgis.refractions.net/documentation/manual-svn/ST_MakeLine.html 
if you have 2 points and no line)

And quay is some sort of polygon.

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
gt at fks.be
Sent: Saturday, February 14, 2009 11:31 AM
To: postgis-users at postgis.refractions.net
Cc: guythomas at telenet.be
Subject: [postgis-users] Which postGIS functions to use?

I have a "network component" (= part of a waterway) defined by 2
coordinates.
I know how to calculate the length of that component.

However, another component, let's say a quay, overlaps with the component. I
know how far it overlaps (in meters) with the component from the beginning
coordinate and I want to calculate the end coordinate of the quay (that
should be on the network component).

How do I do this?

Thank you


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