SO(3) radius querries

[barcode]

I have a set of orientations and need to find all orientations in a radius. In my case, the radius is the smallest delta orientation around any axis (equivalent to Eigen::Quaternionf::angularDistance).

When looking at the nanoflann::SO3_Adaptor, I saw it is using nanoflann::L2_Simple_Adaptor and therefore would generate incorrect results for my metric.

My question: Is it possible to use a metric equivalent to `Eigen::Quaternionf::angularDistance and what would I have to do for this?

[jlblancoc]

You are right, the non-Euclidean part of the library needs an clean up and upgrade...