Description:
This function finds values that resemble the the FITS keywords CRVAL1/2/3..,
CRPIX1/2/3..., CRDELT1/2/3... and CROTA2, on the assumption that the base Frame in the supplied
FrameSet describe GRID coords (i.e. FITS pixel coords), and the current Frame describe the required
WCS. It is not restricted to 2D FrameSets.
If the FrameSet can be written to a FitsChan successfully using FITS-WCS encoding, the the resulting
keyword values are returned. Otherwise, the values are estimated by transforming closely spaced pixel
positions along each axis. If the current Frame contains a SkyFrame, and the SkyFrame has a defined
reference position, then this position specifies the returned CRVAL values. Otherwise, the reference
position is assumed to be at the central pixel.
Invocation
void atlGetPixelParams( AstFrameSet
fset, int
dims, int degs,
double crpix,
double crval,
double cdelt,
double crota,
int status
)
Arguments
fset
The FrameSet.
dims
Pointer to an array supplied holding the number of
pixels along each edge of the pixel array. The number of elements in this array should
match the number of axes in the base Frame of " fset" .
degs
If non-zero, then the crval,
cdelt and crota values for sky axes are returned in units of degrees. Otherwise they are
returned in radians.
crpix
Pointer to an array returned holding the position of the reference
pixel in the base Frame of " fset" . The number of elements in this array should match
the number of axes in the base Frame of " fset" .
crval
Pointer to an array returned
holding the position of the reference pixel in the current Frame of " fset" . The number of
elements in this array should match the number of axes in the current Frame of " fset" .
cdelt
Pointer to an array returned holding the geodesic distance along each edge of the
reference pixel, measured within the current Frame of " fset" . The number of elements in this
array should match the number of axes in the base Frame of " fset" .
crota
Pointer to a
double in which to return the angle from north in the current frame of " fset" to the second
spatial pixel axis, measured positive through east. This will be returned set to AST__BAD if
the current frame of " fset" does not contain a SkyFrame.
status
The global status.