[ 源代码： nanoflann ]
软件包：libnanoflann-dev（1.3.2+ds-1）
C++11 header-only library for Nearest Neighbor Search with KD-Trees
Nanoflann is a fork of the FLANN library. Originally born as a child project of the Mobile Robot Programming Toolkit, nanoflann is now available as stand-alone library.
It trades some of the flexibility of FLANN for raw execution speed and is much more memory efficient, as it avoids unnecessary copies of point cloud data.