[postgis-users] Interpolate Point

[Chris Matheson]

You can extract a linestring from a multilinestring using the 
geometryN(geometry, n) where n denotes the index of the linestring you 
wish to extract.  I have this problem often when importing shapefiles 
from ESRIs software, single lines suddenly become multilinestrings.  use 
geometryN(the_geom, 1) to get them back as lines.

Hope this is helpful.

Chris M

sergio at labtrans.ufsc.br wrote:

>Hello again,
>
>   My problem is the following one:  I need to interpolate a point with a
>line, being that for this I possess two tables, I was trying to use the
>following command:
>  - SELECT line_interpolate_point(f.geom, line_locate_point(f.geom,
>c.geom)) from railroad f, city c;
>  Where geom of the railroad is a field MULTILINESTRING and geom of the city
>is a field POINT, this command does not function, therefore the first
>argument of line_locate_point must be LINE and not MULTILINESTRING, would
>like to know if somebody possue some suggestion of as I can tranformar
>this MULTILINESTRING in LINE or if exists some function that finds the
>line next to a point and that it returns as resulted the point where the
>original point is interpolated with the line.
>
>grateful,
>Sérgio Zarth Jr.
>
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