Manpage of regrid
Section: User Commands (1)
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regrid - Regrid an image dataset
REGRID regrids an image by interpolating. The output coordinate
system can be specified by a template image or by
axis descriptors. Blanked input pixels are excluded from the
interpolation. Regridding of any combination of the first three
axes of an image is supported.
REGRID correctly handles conversion
* Between different projection geometries (e.g. SIN, NCP, TAN,
* Between equatorial and galactic coordinates.
* From a B1950 input to J2000 output and visa versa, as well
as B1950 to B1950, and J2000 to J2000.
* Between radio/optical velocity definitions and
LSR/barycentric velocity rest frames.
Nearest neighbour `interpolation' is used for axes smaller in
size that 5 pixels. Otherwise an cubic interpolation is used.
The input image name. No default.
The output image name. No default.
Specify axes to regrid. For example, axes=1,2 will regrid
axes 1 and 2, or axes=2,3 will regrid axes 2 and 3.
The default is all axes.
Input template image. The axis descriptors of the regridded
image, for those axes specified by keyword "axis", are those
of the template image. If neither a template nor a set of
"descriptors" (see below) are given, the input is used as an
If "tin" is unset, this gives the reference value, reference
pixel, pixel increment, and number of pixels for the axes
selected by keyword "axes" of the output image, respectively.
Note that for RA/DEC axes, the reference values are in radians,
and the increments are in radians on the sky. Thus,
dRA = dX / cos(dec) and dDEC = dY where you specify dX and dY.
Defaults are no axis descriptors.
Extra processing options. Several can be given, separated by
commas. Only the minimum characters to avoid ambiguity is
noscale Produce a cube where the RA/DEC cell size does not
scale with frequency/velocity.
offset The coordinate system described by the template or
descriptors is modified (shift and expansion or
contraction) by an integral number of pixels so that
it completely encloses the input.
nearest Use nearest neighbour interpolation rather than the
default higher order interpolation scheme.
galeqsw Switch the output coordinate system between
equatorial and galactic.
equisw Switch the equinox of the output between B1950 and
Output map projection. Possible values are "sin", "tan", "arc",
"ncp", "car" or "gls". Note that the NCP projection has a
singularity at the equator. The default is not to change the
Set the rotation between the sky and the image to be this angle,
in degrees. The positive value of the angle gives an eastward
rotation of the sky grid relative to the pixel grid.
The default is not to change the rotation from that of
the template, or to have no rotation when there is no template.
Interpolation tolerance. Tolerate an error of as much as "tol"
in converting pixel locations in the input to the output. The
default is 0.05. It must be less that 0.5.
grid.for,v 1.4 2011/06/27 21:30:32 pteuben Exp $
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Time: 18:35:38 GMT, July 05, 2011