lsst.afw g87b8406481+38fdbcbd0f
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Functions
lsst.afw.geom.wcsUtils Namespace Reference

Functions

def getSipMatrixFromMetadata (metadata, name)
 
def computePixelToDistortedPixel (pixelToFocalPlane, focalPlaneToFieldAngle)
 

Function Documentation

◆ computePixelToDistortedPixel()

def lsst.afw.geom.wcsUtils.computePixelToDistortedPixel (   pixelToFocalPlane,
  focalPlaneToFieldAngle 
)
Compute the transform ``pixelToDistortedPixel``, which applies optical
distortion specified by ``focalPlaneToFieldAngle``.

The resulting transform is designed to be used to convert a pure TAN WCS
to a WCS that includes a model for optical distortion. In detail,
the initial WCS will contain these frames and transforms::

    PIXELS frame -> pixelToIwc -> IWC frame ->  gridToIwc -> SkyFrame

To produce the WCS with distortion, replace ``pixelToIwc`` with::

    pixelToDistortedPixel -> pixelToIwc

Parameters
----------
pixelToFocalPlane : `lsst.afw.geom.TransformPoint2ToPoint2`
    Transform parent pixel coordinates to focal plane coordinates
focalPlaneToFieldAngle : `lsst.afw.geom.TransformPoint2ToPoint2`
    Transform focal plane coordinates to field angle coordinates

Returns
-------
pixelToDistortedPixel : `lsst.afw.geom.TransformPoint2ToPoint2`
    A transform that applies the effect of the optical distortion model.

Definition at line 65 of file wcsUtils.py.

◆ getSipMatrixFromMetadata()

def lsst.afw.geom.wcsUtils.getSipMatrixFromMetadata (   metadata,
  name 
)
Extract a SIP matrix from FITS TAN-SIP WCS metadata.

Omitted coefficients are set to 0 and all coefficients may be omitted.

Parameters
----------
metadata : `lsst.daf.base.PropertySet`
    FITS metadata.
name : `str`
    Name of TAN-SIP matrix (``"A"``, ``"B"``, ``"Ap"``, or ``"Bp"``).

Returns
-------
`numpy.array`
    The SIP matrix.

Raises
------
TypeError
    If the order keyword ``<name>_ORDER`` (e.g. ``AP_ORDER``) is not found,
    the value of the order keyword cannot be read as an integer,
    the value of the order keyword is negative,
    or if a matrix parameter (e.g. ``AP_5_0``) cannot be read as a float.

Definition at line 34 of file wcsUtils.py.