RELION (for REgularised LIkelihood OptimisatioN) is a stand-alone computer program for Maximum A Posteriori refinement of (multiple) 3D reconstructions or 2D class averages in cryo-electron microscopy. It is developed in the research group of Sjors Scheres at the MRC Laboratory of Molecular Biology.
The underlying theory of MAP refinement is given in a scientific publication . If RELION is useful in your work, please cite this paper.
The more comprehensive documentation of RELION is stored on the Wiki
More extensive options and configurations are available here, but the outlines to clone and install relion for typical use are made easy through cmake.
On ubuntu machines, installing cmake, the compiler, and additional dependencies (mpi, fftw) is as easy as:
sudo apt install cmake build-essential mpi-default-bin mpi-default-dev libfftw3-dev
On other systems it is typically just as easy, you simply have to modify "apt" to the appropriate package manager. You will also need git, which is just as easy;
sudo apt install git
Once git and cmake are installed, relion can be easily installed through
git clone https://github.com/3dem/relion.git
cd relion
mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX=/where/to/install/ ..
make -j4
make install
(NOTES: "/where/to/install/.." is typically "/usr/local/relion". Make sure you create this directory beforehand. Installing to that location requires sudo, so in this case be sure to use "sudo make install" instead of "make install" in the last step.)
These steps will download the source-code, create a build-directory, then configure and build relion, and lastly install it to be generally available on the system.
RELION is intermittently updated, with both minor and major features. To update an existing installation, simply use the following commands
cd relion
git pull
cd build
make -j4
make install # (or "sudo make install")