Matching with FLANN

FLANN stands for Fast Library for Approximate Nearest Neighbors. It is an open source library under the permissive 2-clause BSD license and it is available on GitHub at https://github.com/flann-lib/flann. There, we find the following description:

"FLANN is a library for performing fast approximate nearest neighbor searches in high dimensional spaces. It contains a collection of algorithms we found to work best for the nearest neighbor search and a system for automatically choosing the best algorithm and optimum parameters depending on the dataset. FLANN is written in C++ and contains bindings for the following languages: C, MATLAB,Python, and Ruby."

In other words, FLANN has a big toolbox, it knows how to choose the right tools for the job, and it speaks several languages. These features make the library fast and convenient. Indeed, FLANN's authors claim that it is 10 times faster than other nearest-neighbor search software for many datasets.

Although...