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

[sylvain dubouis]

It works,
thanks for your help

2008/1/30, Kevin Neufeld <kneufeld at refractions.net>:
>
> 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
> >     >
> >
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