This is a C++11 library for detecting AprilTags in images. It is a (faster) variant of the excellent library originally written by Michael Kaess: http://people.csail.mit.edu/kaess/apriltags/.
It only differs in the fact that some image processing operations, that were implemented "by hand" in the original library, have been replaced by OpenCV for improved performance. Additionally, a part of the computations was multithreaded using std::thread.
The changes improve the performance from around 7.5 fps to around 12 fps for a 1280x720 camera image on my (quad core) machine.
This library is based on the implementaton by Michael Kaess. Just like his library, this library is available as open source under GNU LGPL version 2.1.
Ed Olson, AprilTag: A robust and flexible visual fiducial system, Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), 2011