Boost C++ Libraries: Ticket #12725: boost::geometry::distance compile errors with 3D segment primitives

version, severity changed; cc set

Sun, 08 Jan 2017 19:59:58 GMT

cc arturoblas@… added
version Boost 1.61.0 → Boost 1.60.0
severity Problem → Showstopper

Mon, 16 Jan 2017 00:02:05 GMT

Can you please give some feedback about this ticket to know whether to rely on Boost for this functionality or try to find other options?

type changed

awulkiew — Mon, 16 Jan 2017 02:39:25 GMT

type Bugs → Feature Requests

Yes, it seems that disjoint/intersects is not yet implemented for N-dimensional segments. And distance() calls this algorithm.

As a workaround you could store bounding boxes of segments in the R-tree, then search for Boxes nearest to some query Box using iterative query, in each iteration check the actual distance between segments using your own implementation and stop if your k-th found segment is closer than the distance between the bounding box passed into the query and the bounding box found in the current iteration. So basically use the index how you'd use it for any other Geometry.

Mon, 16 Jan 2017 02:54:04 GMT

Thanks for your feedback, this is what I had in mind but I was hoping I could just hook in my own intersection/distance function providing segment distance in 3D space.

Also, the main issue from a user's perspective is the lack of an statement in the documentation so it's explicitly stated that algorithms may not work for primitives with 2+ dimensions.

Is there an ETA for implementing this?

awulkiew — Mon, 16 Jan 2017 08:02:35 GMT

I'd discourage you from hooking in your own functions in case something changed in the future internally in the rtree (e.g. different functions were used). But if you'd like to try it you could overload bg::comparable_distance(segment, segment) and bg::comparable_distance(segment, box), e.g. like that:

namespace boost { namespace geometry {
    template <typename Box>
    float comparable_distance(segment const& s, Box const& b) { return 0; }
    float comparable_distance(segment const& s1, segment const& s2) { return 0; }
}}

Box would be of type internally used in the R-tree to represent nodes, so bg::model::box<...>.

No ETA, currently we're adding support for 2d geographic CS. But you could consider contributing your own implementation. :)

Mon, 16 Jan 2017 19:28:28 GMT

Thanks again for your help. That looks like a good way to test things actually work but not a long term solution obviously.

I could share with you my 3D segment distance implementation if that would help in any way.

Best.