Hi Stephan, On 23-5-2012 17:08, Stephan Menzel wrote:
Hi all,
before I begin, let me tell that geometry is not exactly my strong suite so please forgive my probably dumb question.
I have started to work with boost geometry which, I find very neat, and assembled a line string.
Now I basically need a method that gives me a point to a length value. Like when my linestring is 100 units long and I say give me the point at 3 I want the exact position of the point (coordinates) as if I were following the line for exactly 3 units.
I have an approach that would allow me to implement this myself by following the segments (possibly after indexing them) but I have a feeling that one of those many functions provided by the library itself might do just that and I simply don't know it. If anyone knows if such is the case, would be nice to give me a heads up.
There is no such function built in. You are probably looking for a function as LocateAlong, http://postgis.refractions.net/documentation/manual-2.0/ST_LocateAlong.html This function is (ever) planned, it is part of the OGC SF specification. But it is not there yet. Regards, Barend