NAME

     ijkmcube - generate isosurface using Marching Cubes

SYNOPSIS

     ijkmcube [-octree] [-region L] [-nep] [-snap D]  [-ivol]  [-
     list]  [-subsample S] [-dir {isotable_directory}] [-off|-iv]
     [-o {output_filename}] [-stdout] [-stdout]  [-help]  [-time]
     [-nowrite] {isovalue1 isovalue2 ...} {input filename}

DESCRIPTION

     ijkmcube generates an isosurface using Marching Cubes or one
     of  its variants.  Input file contains scalar values in NRRD
     (Nearly Raw Raster Data) format.  When more  than  one  iso-
     value  is  specified,  the  program will generate a separate
     output file for each.

OPTIONS

     -octree
          Create an octree and identify grid cubes intersected by
          the  isosurface using the octree.  Speeds up isosurface
          generation when more than one isovalue is specified.

     -region L
          Divide the grid into regions  of  LxLxLx...  edges  and
          identify  grid  regions  intersected by the isosurface.
          Speeds up isosurface generation when more than one iso-
          value is specified.

     -nep Use an isosurface table with  negative,  equals  (zero)
          and  positive  vertex labels.  The equals vertex labels
          represents vertices whose scalar value equals the  iso-
          value.

     -snap D
          Apply algorithm SnapMC. Construct the  isosurface  mesh
          by  setting  the  scalar  value of grid vertices within
          distance D of the isosurface  to  the  isovalue.   This
          effectively  "snaps" isosurface vertices onto that grid
          vertex.  Construct the mesh using  the  NEP  (negative,
          equals, positive) lookup table and then move isosurface
          vertices back to original locations on the isosurface.

          Distance D is between 0.0  and  0.5  and  represents  a
          fraction of the grid edge.

     -ivol
          Construct an interval volume.

     -subsample S
          Subsample the input grid and then construct the isosur-
          face.   Subsample  the  input grid so that S grid edges
          are replaced by a single grid edge.

     -dir {isotable_directory}
          Set the  directory  containing  the  isosurface  lookup
          table  .xit (XML Isosurface Table) file.  An isosurface
          lookup table file of the appropriate dimension and type
          is required.

     -off Output the mesh in Geomview .off format. (Default.)

     -iv  Output the mesh in OpenInventor .iv format.

     -o {output_filename}
          Specify the output file name.  If the output file  name
          is not specified, the program constructs an appropriate
          file name.

     -stdout
          Send the output to standard output.

     -help
          Print a help message.

     -time
          Print program execution time information.

     -nowrite
          Do not write any output file.  Useful in  debugging  or
          in timing executions without creating output.

NOTES

     -- Isosurface generation in 3D requires the .xit  (XML  Iso-
     surface Table)
      isosurface lookup table file iso.cube.3D.xit.

     -- Isosurface generation in 4D requires the  xit  isosurface
     lookup table file iso.cube.4D.xit.

     -- Interval volume generation in 3D requires the xit isosur-
     face lookup table file ivol.cube.3D.xit.

     -- Isosurface generation in 3D  with  the  options  -nep  or
     -snap  D  requires  the  xit  isosurface  lookup  table file
     iso.nep.cube.3D.xit.

SEE ALSO

     ijkgentable(1),xit(5).

AUTHOR

     Sundaresan Raman, Rephael Wenger