[postgis-users] computing the center of a Linestring ?

[Obe, Regina]

Smith,
 
Take a look at the Linear Referencing functions.  To get the center
point that is guaranteed to fall on the line, I would use
ST_line_interpolate_point(linestring, 0.5)
 
http://postgis.refractions.net/documentation/manual-svn/ch06.html#id2616
367
 
Be forewarned the above link will be changing soon since the SVN manual
is a moving target and will be added more examples shortly.
 
Hope that helps,
Regina

________________________________

From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
Smith Roman
Sent: Thursday, October 16, 2008 7:28 AM
To: Users Postgis
Subject: [postgis-users] computing the center of a Linestring ?


HI,
I have a base map of lagos, Nigeria that contains roads, streets and
points of interest (POI). Unfortunately the street addresses are not
geocoded. I was told they are possible ways to geocode such kind of data
e.g. geocode to a street name, geocode to a street intersection and/or
point of interest.
 
I will like to ask what postgis functions can be used to do this kind of
operation ? 
 
For example, If I intend geocoding to a street name, this will imply
assigning point coordinates to represent each street, to this i will
need to get the center point of each street. By their nature streets and
roads are not straight.
 is there a postgis function for computing the center of a Linestring ?
especially if the linestring is not straight but has a few curves. All
the roads and streets are represented as linestrings in my data.
 
It will be appreciated if I can get suggestions on the geocoding method
to use and how postgis can be used to implement it. 
 
Thanks, 
 
Smith.



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