LSST Applications  21.0.0-172-gfb10e10a+18fedfabac,22.0.0+297cba6710,22.0.0+80564b0ff1,22.0.0+8d77f4f51a,22.0.0+a28f4c53b1,22.0.0+dcf3732eb2,22.0.1-1-g7d6de66+2a20fdde0d,22.0.1-1-g8e32f31+297cba6710,22.0.1-1-geca5380+7fa3b7d9b6,22.0.1-12-g44dc1dc+2a20fdde0d,22.0.1-15-g6a90155+515f58c32b,22.0.1-16-g9282f48+790f5f2caa,22.0.1-2-g92698f7+dcf3732eb2,22.0.1-2-ga9b0f51+7fa3b7d9b6,22.0.1-2-gd1925c9+bf4f0e694f,22.0.1-24-g1ad7a390+a9625a72a8,22.0.1-25-g5bf6245+3ad8ecd50b,22.0.1-25-gb120d7b+8b5510f75f,22.0.1-27-g97737f7+2a20fdde0d,22.0.1-32-gf62ce7b1+aa4237961e,22.0.1-4-g0b3f228+2a20fdde0d,22.0.1-4-g243d05b+871c1b8305,22.0.1-4-g3a563be+32dcf1063f,22.0.1-4-g44f2e3d+9e4ab0f4fa,22.0.1-42-gca6935d93+ba5e5ca3eb,22.0.1-5-g15c806e+85460ae5f3,22.0.1-5-g58711c4+611d128589,22.0.1-5-g75bb458+99c117b92f,22.0.1-6-g1c63a23+7fa3b7d9b6,22.0.1-6-g50866e6+84ff5a128b,22.0.1-6-g8d3140d+720564cf76,22.0.1-6-gd805d02+cc5644f571,22.0.1-8-ge5750ce+85460ae5f3,master-g6e05de7fdc+babf819c66,master-g99da0e417a+8d77f4f51a,w.2021.48
LSST Data Management Base Package
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.

65 def computePixelToDistortedPixel(pixelToFocalPlane, focalPlaneToFieldAngle):
66  """Compute the transform ``pixelToDistortedPixel``, which applies optical
67  distortion specified by ``focalPlaneToFieldAngle``.
68 
69  The resulting transform is designed to be used to convert a pure TAN WCS
70  to a WCS that includes a model for optical distortion. In detail,
71  the initial WCS will contain these frames and transforms::
72 
73  PIXELS frame -> pixelToIwc -> IWC frame -> gridToIwc -> SkyFrame
74 
75  To produce the WCS with distortion, replace ``pixelToIwc`` with::
76 
77  pixelToDistortedPixel -> pixelToIwc
78 
79  Parameters
80  ----------
81  pixelToFocalPlane : `lsst.afw.geom.TransformPoint2ToPoint2`
82  Transform parent pixel coordinates to focal plane coordinates
83  focalPlaneToFieldAngle : `lsst.afw.geom.TransformPoint2ToPoint2`
84  Transform focal plane coordinates to field angle coordinates
85 
86  Returns
87  -------
88  pixelToDistortedPixel : `lsst.afw.geom.TransformPoint2ToPoint2`
89  A transform that applies the effect of the optical distortion model.
90  """
91  # return pixelToFocalPlane -> focalPlaneToFieldAngle -> tanFieldAngleToocalPlane -> focalPlaneToPixel
92  focalPlaneToTanFieldAngle = makeTransform(linearizeTransform(focalPlaneToFieldAngle,
93  lsst.geom.Point2D(0, 0)))
94  return pixelToFocalPlane.then(focalPlaneToFieldAngle) \
95  .then(focalPlaneToTanFieldAngle.inverted()) \
96  .then(pixelToFocalPlane.inverted())
def computePixelToDistortedPixel(pixelToFocalPlane, focalPlaneToFieldAngle)
Definition: wcsUtils.py:65
std::shared_ptr< TransformPoint2ToPoint2 > makeTransform(lsst::geom::AffineTransform const &affine)
Wrap an lsst::geom::AffineTransform as a Transform.
lsst::geom::AffineTransform linearizeTransform(TransformPoint2ToPoint2 const &original, lsst::geom::Point2D const &inPoint)
Approximate a Transform by its local linearization.

◆ 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.

34 def getSipMatrixFromMetadata(metadata, name):
35  """Extract a SIP matrix from FITS TAN-SIP WCS metadata.
36 
37  Omitted coefficients are set to 0 and all coefficients may be omitted.
38 
39  Parameters
40  ----------
41  metadata : `lsst.daf.base.PropertySet`
42  FITS metadata.
43  name : `str`
44  Name of TAN-SIP matrix (``"A"``, ``"B"``, ``"Ap"``, or ``"Bp"``).
45 
46  Returns
47  -------
48  `numpy.array`
49  The SIP matrix.
50 
51  Raises
52  ------
53  TypeError
54  If the order keyword ``<name>_ORDER`` (e.g. ``AP_ORDER``) is not found,
55  the value of the order keyword cannot be read as an integer,
56  the value of the order keyword is negative,
57  or if a matrix parameter (e.g. ``AP_5_0``) cannot be read as a float.
58  """
59  arr = _getSipMatrixFromMetadata(metadata, name)
60  if arr.shape == (): # order=0
61  arr.shape = (1, 1)
62  return arr
63 
64 
def getSipMatrixFromMetadata(metadata, name)
Definition: wcsUtils.py:34