[postgis-users] the nearest point of a line from a point

[Kevin Neufeld]

Hi Sylvain,

ST_ prefixed functions is the new way to access PostGIS methods, 
following the SQL-MM specifications. It sounds like you'll need to 
upgrade your PostGIS version.

See this thread in the archives for more info.
http://postgis.refractions.net/pipermail/postgis-users/2007-September/016997.html

-- Kevin

sylvain dubouis wrote:
> Thanks Kevin,
> It seems to be the good solution, but I can't execute "st_" functions :
>
> ERROR:  function st_line_locate_point(geometry, geometry) does not exist
> HINT:  No function matches the given name and argument types. You may 
> need to add explicit type casts.
>
> Do you know why? and how I can Install this functions on my 
> postgresql/postgis server
>
> Sylvain
>
> 2008/1/30, Kevin Neufeld <kneufeld at refractions.net 
> <mailto:kneufeld at refractions.net>>:
>
>     See the section on linear referencing (sec. 6.2.7).
>     (http://postgis.refractions.net/docs/ch06.html#id2775904)
>
>     You'll need to use two methods.
>
>     ST_line_locate_point(LineString, Point) returns the percentage
>     along the
>     the LineString the closest point will occur.
>
>     ST_line_interpolate_point(linestring, location) returns the geometric
>     point given a LineString and a percentage along.
>
>     SELECT ST_line_interpolate_point(line_geom,
>     ST_line_locate_point(line_geom, point_geom))
>     FROM ...
>
>     Cheers,
>     Kevin
>
>     sylvain dubouis wrote:
>     > hello, I have a point and a line.
>     > I'd like to know the nearest point on the line from the  point.
>     > but I don't find any function to do this... is there one?
>     > thanks for your help.
>     > Sylvain
>     >
>     ------------------------------------------------------------------------
>     >
>     > _______________________________________________
>     > postgis-users mailing list
>     > postgis-users at postgis.refractions.net
>     <mailto:postgis-users at postgis.refractions.net>
>     > http://postgis.refractions.net/mailman/listinfo/postgis-users
>     >
>     _______________________________________________
>     postgis-users mailing list
>     postgis-users at postgis.refractions.net
>     <mailto:postgis-users at postgis.refractions.net>
>     http://postgis.refractions.net/mailman/listinfo/postgis-users
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users
>