vinter - 3D Slice Interpolation
          Interpolation between slices in a multiband image

     vexpand3d - Voxel replication
          Expand the volume in the three directions x, y, z

     vzbuff - Compute the zbuffer through a ray casting algorithm
          Given the projection view, and the volume data, outputs
          the z-buffer and optionally the voxel coordinates and

     visnorm - Compute the normal from the zbuffer
          From the zbuffer, estimate the normals. This will gen-
          erate the so-called image space shading

     vvsnorm - Compute the normal from voxel space
          From the visible surface voxel coordinates and the
          volume data, estimates the surface normals to generate
          the so-called voxel space and object space shadings

     vvoxext - Show voxels from its coordinates
          From a 3-band coordinate file and a volume, creates a
          correspondent voxel image.  This is useful to show vox-
          els at the surface specified by the 3-band coordinate

          Add thickness to volume rendering

     vshad - Shade the output file from z-buffer
          Shading part of the ray-cast rendering algorithm

     vthresh3d - Threshold through bands
          Generate a multiband binary image from a multiband gray

     vqmed3d - 3D median filter
          Do a median filter in a multiband image as 3D data

     vconv3d - 3D convolution
          Do a spatial periodic convolution of two multiband
          images as 3D data

     vfft3d - FFT 3D
          Radix 2 3D fft

          Log of Magnitude of fft3d

     vinsert3d - Insert a sub-volume image
          Insert, (erasing the local of insertion) a sub-volume
          image into a larger one

     vpad3d - Pad 3D
          Pad in a volume data

     vaband - Add or Append bands
          Insert a range of bands of an image into another

     vdband - Delete bands
          Remove a range of bands from an image

     vmband - Move bands within a multiband image
          Rearrange the bands within an image

          Create a montage image by placing bands side by side in
          rows and columns

          Extract 3 planes (constant x, y and z) from a 3D image

          Create a byte frame volume

     vgauss3d - 3D gaussian image
          Generate a gaussian density distribution in a volume

     vimpul3d - volume with impulses
          Generate a volume data with impulses

          Create a 3D image containing 3 orthogonal planes