FILL_CUBE

        FILL_CUBE

    This program resamples an input data cube on  a  finer  grid   for   the
    first  two  dimensions (hence the data cube is treated as an ensemble of
    images).   The  output  grid  may  be  explicitly  determined  from  the
    conversion formulae of the two first axis, or implicitly from the number
    of pixels of the two first axis and the input cube conversion  formulae.
    Two different methods are available for the resampling :

    The SLOW method, which is general and takes properly  into  account  the
    input blanking value.  This method is based on the same algorithm as the
    RANDOM command in  GreG.   It   triangulates   the   input   non-blanked
    values  and  uses Lagrange polynomials to interpolate on the finer grid.
    For optimisation purposes,  the  same  triangulation  is  used  for  all
    planes,  which  assumes  that the same pixels are blanked in all planes.
    If this is not the case, the individual planes should be extracted,  and
    processed separately.

    The FAST method, which ignores   the   input   blanking   value.    This
    method  is  based on the same algorithm as the RESAMPLE command in GreG.
    It is faster, but should be used only if no input pixel is blanked.

    If the data is undersampled, this task is  the  recommended  second step
    in  the  data  analysis  of  a  cube produced by command ANALYSE\CUBE in
    CLASS, immediately after  the  TRANSPOSE  program.   Task  MAKE_CUBE  is
    preferable for oversampled data.