from astropy.modeling.models import Mapping
from .assign_wcs_step import AssignWcsStep
__all__ = ["AssignWcsStep", "_distorted_to_undistorted"]
[docs]
def _distorted_to_undistorted(wcsobj):
"""
This is a convenience function for Build 17 which returns the transform
from "detector" to "undistorted pixels".
TODO: Add an 'undistorted' coordinate frame. The transform from detector to
'undistorted' is currently in the SIAF from 'detector' to 'Ideal' frame.
The split is done in the code now. In the future this should be done in the
distortion reference file and become part of the WCS.
"""
transform = wcsobj.get_transform("detector", "v2v3")
shifts = transform[:4]
poly = transform[5:7]
return shifts | Mapping((0, 1, 0, 1)) | poly