[postgis-users] Interpolate Point

[strk at refractions.net]

In order to "explode" multi geometries you need to use the
dump(geometry) function. This would return a set of basic components
(POINT,LINE,POLYS). One you have these you can use distance()
to find the nearest line to your point. Then you proceed
with locate and interpolate.

--strk;

On Thu, Jan 12, 2006 at 09:04:47AM -0200, 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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