vbsim

vbsim is a very simple program to generate 3D and 4D volumes with some known characteristics. It may be useful for some kinds of testing and validation.

Here's the help text:

VoxBo vbsim (v1.8.5/Jun 14 2011)
usage: vbsim [flags] file
flags:
  -d <x> <y> <z> <t>    set dimensions
  -c <vol>              "anatomy" file (added to image)
  -s <seed>             seed for random number generator
  -n <u> <v> <fwhm>     noise mean,variance,and smoothness
  -z <x> <y> <z> <t>    set voxel sizes (t is usually TR in ms)
  -o <filename>         output filename (default \"data.tes\"
  -h                    help
  -v                    version
notes:
  FWHM is in voxels, although voxel sizes default to 1x1x1mm anyway.

  noise defaults to 10,5,0 if -n isn't specified.

  If y, z, and t dimensions are 0, a 1D vector file is created.  If
  just t is 0, a 3D volume is created.  In the former case, the fwhm
  is ignored, but you still have to provide it.

  vbsim uses GSL's pseudo random number generator, specifically
  gsl_rng_mt19927, and uses gsl_ran_gaussian() to generate random
  variates with a Gaussian distribution.  If you use the -s flag to
  set the seed, you can get the program to produce predictable output
  (perhaps useful for testing purposes and for repeatable resampling
  tests).  Any integer in the 0-2^32 range is fine.  If -s isn't
  provided, the value is taken from /dev/urandom (system permitting).