apply_warp - Fast application of displacement field  

1997 Ulrik Kjems, DSP/IMM, Technical University of Denmark, uk@imm.dtu.dk
Use:
  apply_warp inputvol field outputvol

Applies a 3D deformation field to a volume. The deformation field is 
represented as a 4 dim. volume, with the last (outer) index being 0, 1
or 2 for X, Y or Z coordinate of the displacement vector. The displacement 
is stored in units of cm's. All data types are supported.

Nearest neighbor interpolation is used.

apply_warp -h produces above information