lsst.afw.geom.wcsUtils Namespace Reference
Functions | |
| getSipMatrixFromMetadata (metadata, name) | |
| computePixelToDistortedPixel (pixelToFocalPlane, focalPlaneToFieldAngle) | |
Function Documentation
◆ computePixelToDistortedPixel()
| 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.
65def 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())
◆ getSipMatrixFromMetadata()
| 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.
34def 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
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