- NAME
UPDATE_DISTORT
- PURPOSE
Update SIP nonlinear distortion coefficients for a linear transformation
- EXPLANATION
The SIP coefficients can account for nonlinearities in the astrometry
of an astronomical image. When the image is compressed or expanded
these coefficients must be adjusted in a nonlinear way.
- CALLING SEQUENCE
UPDATE_DISTORT, distort, xcoeff, ycoeff
- INPUT/OUTPUT
distort - structure giving SIP coefficients. See extast.pro for
description of the SIP distortion structure
xcoeff - 2 element numeric vector describing the linear transformation
xp = xcoeff[0]*x + xcoeff[1]
xcoeff - 2 element numeric vector describing the linear transformation
yp = ycoeff[0]*x + ycoeff[1]
- METHOD
The procedure TRANSFORM_COEFF is used to determine how the
coefficients change under the linear transformation.
See example of usage in hrebin.pro
- REVISION HISTORY
Written, December 2007 W. Landsman