CGAL users discussion list

["Mount, Jerry" <>]

Hello everyone,

 

I am trying to calculate the intersection of polygons in 3D space.  Sorry for the non-technical and somewhat GIS-based description that follows:

 

I am looking at pedestrian movement through a 3D network based on polylines.  I am looking at all simple, near-shortest paths within a time constraint to determine the minimum and maximum times required to reach the nodes in the network.  After that, I build 3d polylines that connect the min and max time to reach the nodes to the end nodes for that edge - time is represented as a z-value.  The result is that I have an upper and lower edge representing the time-to-reach those nodes.  I can build a polygon that represents the network edge by connecting the from-node min/max and the to-node min/max.  Ok, all of this works - but now I want to examine (if) or (where/when) tracks from multiple agents intersect. 

 

Since I can build the polygons (which resemble straight ribbons with the lower edge representing the min time to reach and the upper edge representing the max time to reach) - I've written a function calculates the intersection points for comparing tracks that use the same network edge.  However, I was wondering if there is an intersect function that works on polygons in 3D space.  I found the section in the manual -18.2.3 Polygons in 3D Space - and found CGAL::intersection but this seems to be only for 2D.  Is there any CGAL function that can calculate the intersection of polygons in 3D space?

 

Thanks for any information,

Jerry