Experimenting with FLANN as included in openCV 3.1 (December, 2015) I found the old version 1.6.10 (May 2011). Is there a special reason not to use the latest 1.8.4 (January 2013)? Looking at the changelog the authors provided a lot of fixes and enhancements. Is there a reason to keep this old version? Looking at the changelog of openCV the 1.6 of FLANN was included in 2.3.1 (August, 2011) and improved by Pierre-Emmanuel Viel in 3.0 alpha (August, 2014). Are those enhancements so extensive that it is better not upgraded?