FIND /MASK

        LAS\FIND /MASK [FileName]

    Select observations according the given mask.

    The  file name should refer to a GDF file providing a 2D (position-posi-
    tion) mask with <=0 or blank values (not selected), or >0 (selected) re-
    al  values.  The  spectra from the input index are selected according to
    their position (lamof, betof) on the mask. Positions completely  out  of
    the  mask  are  not  selected. Note that this command does not check the
    consistency of the projection center, projection  kind,  and  projection
    angle (only offsets are used).

    This  option is best suited for use with the weight file (.wei) produced
    by the command XY_MAP, in which zero weights are put where  no  data  is
    available.  Using this weight file with FIND /MASK will thus ignore pix-
    els/spectra with no data at all (all blank values).

    Another possibility is to produce a custom mask from an image, e.g.
      G\IMAGE myimage.gdf  ! or mycube.lmv
      G\LIMITS /RG
      G\SET BOX MATCH
      G\PLOT
      G\BOX
      G\POLYGON                           ! Define with cursor
      G\MASK OUT                          ! Mask pixels OUT of the polygon
      LET RG +1 /WHERE RG.NE.BLANKING[1]  ! Select pixels IN the polygon
      G\WRITE IMAGE mymask.gdf            ! Save into file
    In this example the cursor is used to define the mask, but one  can  use
    his own recipe to define the in/out rules.

    The  default  for FileName is the FILE IN VLM cube name if any, with the
    extension replaced by ".wei". Else, there is no default.