As of Sat Apr 20 14:05:00 2024

OGEOM: Interpolate an image to the geometry of another.


                                   Input image
INNAME                                Image name (name)
INCLASS                               Image name (class)
INSEQ              0.0      9999.0    Image name (seq. #)
INDISK             0.0         9.0    Image disk drive #
                                   Output image
OUTNAME                               Image name (name)
OUTCLASS                              Image name (class)
OUTSEQ            -1.0      9999.0    Image name (seq. #)
OUTDISK            0.0         9.0    Image disk drive #
BLC             0.0      4096.0    Bottom left corner of image
                                     0=>entire image
TRC             0.0      4096.0    Top right corner of image
                                     0=>entire image
IMSIZE          0.0      4096.0    Output image size in pixels
REWEIGHT        0.0         4.0    (1) Interpolation halfwidth
                                   (2) Minimum fraction of good
                                       pixels required (0->1/3)
APARM                              (1)=Delta X in pixels
                                   (2)=Delta Y in pixels
                                   (6)=shift X coordinates : ???
                                   (7)=shift Y coordinates : ???


Type: Task
Use: OGEOM does an interpolation of an image to a rotated, shifted, and
     scaled output image.  It is assumed that the image geometry is
     linear for these purposes.  Use OHGEO for larger fields.

     Interpolation is done only in the first 2 dimensions.  Unlike
     LGEOM, OGEOM will interpolate over blanked pixels so that it can
     fill in small blanked regions and handle edges without having to
     discard image area.
     NOTE: the input subimage is read into dynamically allocated memory.
     Very large input arrays may cause swapping on your computer.

     This task does a straightforward interpolation from the input to
     the output image grid.  This process cannot be completely
     accurate if, for example, one shifts and scales an image and
     then reverses that process.  Greater accuracy will be achieved on
     images with more points per beam and with larger support sizes
     for the interpolator.
  INNAME......The input image name.   Standard defaults.
  INCLASS.....The input image class.  Standard defaults.
  INSEQ.......The input image sequence number. 0 => high
  INDISK......The input image disk drive no. 0 => any
  OUTNAME.....The output image name.  blank => Standard
              defaults based on INNAME.
  OUTCLASS....The output image class.  Standard behavior.
  OUTSEQ......The output image seq. no., 0=> highest unique
              If >0; image will be created if new, overwritten if image
              name exists.
  OUTDISK.....Output disk drive no., 0=> highest with space
  BLC.........The bottom left-hand pixel of the input image which
              becomes the bottom left corner of the input subimage.  The
              value (0,0) means (1,1).
  TRC.........The top right-hand pixel of the input image which becomes
              the top right corner of the subimage.  The value (0,0)
              means take the top right hand corner of the image.
  IMSIZE......Output image size in pixels [1=columns, 2=rows].  Default
              is the input image size.  If the output image size is
              the same as the input size in both axes, then the
              reference pixel is not changed other than by the
              addition of APARM(1) and APARM(2).
  REWEIGHT....Interpolation kernal parameters:
              (1) Half width of the interpolating kernel
                  (1 - 4).  Default = 1
                  Larger support sizes should produce more accurate
                  results at the cost of increased computation.
              (2) Minimum fraction of pixels in interpolation kernal
                  area required for non-blanked output.
                  <= 0 or >= 1  => 0.333
  APARM.......Transformation parameters:
              1 & 2 = shift of coordinate reference point, expressed in
                  output pixels, for x & y relative to the center of the
                  subimage.  Positive moves objects to the right and up
                  relative to center pixel.
              3 = rotation in degrees (positive moves objects
                  counterclockwise relative to the image center as they
                  map from input image to output image).
              4 = scale factor (greater than one moves objects outward
                  from the image center as they map from input to
                  output).  This is applied wrt the image center
                  defined as Naxis(1)/2, Naxis(2)/2 + 1.
              5 = 'differential scale'; this is an extra scale factor
                  applied to the y-axis AFTER the main transformation
                  has been done. This is useful to make spiral galaxies
                  appear face-on. Also, if it is negated the result is a
                  mirror-reflection in the y-axis.
              6 & 7 = Coordinate shift in X and Y in arc seconds.  The
                  measured right ascension and declination of objects
                  will change.  Positive increases the RA and Dec. if
                  the image has the normal orientation (RA increasing to
                  the left, Dec. increasing upwards, no rotation).  Note
                  that this option corrects the shift for the cos of the
                  latitude which only works correctly when there are no
                  rotations.  THIS OPTION DESTROYS THE COORDINATES YOU
                  WENT TO A LOT OF TROUBLE TO MEASURE.  Use it only in
                  dire straights.