[postgis-users] Obtaining a point in a linestring knowing only the distance from start point

Luca Giandoso luca.giandoso at gmail.com
Mon Mar 13 00:52:06 PST 2006

I have a linestring and a point in the linestring. I want to know the
coordinate of the point giving the distance from the start point of
the linstring.

I can already locate the linestring segment where is located the
point, so the problem is reduced to obtaining a point from a line
knowing the distance of the point from the start point.

This problem can be solved with
   line_interpolate_point(linestring, location)
trasforming the distance in a fraction of the line? Or I get a not so
good  approximation?

Maybe it is better to do a classical intersection with the
circumference ( the set of points located at determined distance from
the start point)  and the line?

Thank You
Luca Giandoso

More information about the postgis-users mailing list