Build in IFGT (+ direct+tree)?

[gadomski]

figtree is turning into a bit of a problematic dependancy. Not only is the codebase a bit of a spaghetti pile, but it may be overkill for the problems that we're building cpd to solve. Specifically, since we're going to be using cpd primarily for three-dimensional spatial data, we don't need a solution that scales well at higher dimensions (yet).

Down the road we might want to support higher dimensions (for instance, using cpd with smoothed intensity values?) but I think performant and maintainable code for three dimensions should be the priority for now.

I've been reading through the IFGT user manual for the original IFGT code (from 2006!) and it seems like something I might be able to drop in to cpd itself (maybe with FLANN to do the K-center clustering?). I also should scan around some more to see if anyone's done a newer IFGT.

[gadomski]

Some useful projects to look at:

• http://www.robots.ox.ac.uk/~vgg/software/fastanncluster/
• http://libkdtree.alioth.debian.org/
• https://github.com/jlblancoc/nanoflann

[gadomski]

7a35015a561d1dd85466b806d0eb0915f8919c10