Splice or merge sets of directions over multiple shells into a single set, in such a way as to maintain near-optimality upon truncation


dirmerge [ options ]  subsets bvalue files [ bvalue files ... ] out
  • subsets: the number of subsets (phase-encode directions) per b-value
  • bvalue files: the b-value and sets of corresponding files, in order
  • out: the output directions file, with each row listing the X Y Z gradient directions, the b-value, and an index representing the phase encode direction


  • -unipolar_weight set the weight given to the unipolar electrostatic repulsion model compared to the bipolar model (default: 0.2).

Standard options

  • -info display information messages.
  • -quiet do not display information messages or progress status. Alternatively, this can be achieved by setting the MRTRIX_QUIET environment variable to a non-empty string.
  • -debug display debugging messages.
  • -force force overwrite of output files. Caution: Using the same file as input and output might cause unexpected behaviour.
  • -nthreads number use this number of threads in multi-threaded applications (set to 0 to disable multi-threading).
  • -help display this information page and exit.
  • -version display version information and exit.

Author: J-Donald Tournier (jdtournier@gmail.com)

Copyright: Copyright (c) 2008-2018 the MRtrix3 contributors.

This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, you can obtain one at http://mozilla.org/MPL/2.0/

MRtrix3 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

For more details, see http://www.mrtrix.org/