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lsst.afw g712618294e+4813a5392e
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Classes | |
| class | BoxGrid |
| class | FrameSetInfo |
| class | PermutedFrameSet |
| class | TransformTestBaseClass |
Functions | |
| def | makeSipPolyMapCoeffs (metadata, name) |
| def | makeSipIwcToPixel (metadata) |
| def | makeSipPixelToIwc (metadata) |
| def lsst.afw.geom.testUtils.makeSipIwcToPixel | ( | metadata | ) |
Make an IWC to pixel transform with SIP distortion from FITS-WCS metadata
This function is primarily intended for unit tests.
IWC is intermediate world coordinates, as described in the FITS papers.
Parameters
----------
metadata : lsst.daf.base.PropertySet
FITS metadata describing a WCS with inverse SIP coefficients
Returns
-------
lsst.afw.geom.TransformPoint2ToPoint2
Transform from IWC position to pixel position (zero-based)
in the forward direction. The inverse direction is not defined.
Notes
-----
The inverse SIP terms APn_m, BPn_m are polynomial coefficients x^n y^m
for computing transformed x, y respectively. If we call the resulting
polynomial inverseSipPolynomial, the returned transformation is:
pixelPosition = pixel origin + uv + inverseSipPolynomial(uv)
where uv = inverseCdMatrix * iwcPosition
Definition at line 196 of file testUtils.py.
| def lsst.afw.geom.testUtils.makeSipPixelToIwc | ( | metadata | ) |
Make a pixel to IWC transform with SIP distortion from FITS-WCS metadata
This function is primarily intended for unit tests.
IWC is intermediate world coordinates, as described in the FITS papers.
Parameters
----------
metadata : lsst.daf.base.PropertySet
FITS metadata describing a WCS with forward SIP coefficients
Returns
-------
lsst.afw.geom.TransformPoint2ToPoint2
Transform from pixel position (zero-based) to IWC position
in the forward direction. The inverse direction is not defined.
Notes
-----
The forward SIP terms An_m, Bn_m are polynomial coefficients x^n y^m
for computing transformed x, y respectively. If we call the resulting
polynomial sipPolynomial, the returned transformation is:
iwcPosition = cdMatrix * (dxy + sipPolynomial(dxy))
where dxy = pixelPosition - pixelOrigin
Definition at line 235 of file testUtils.py.
| def lsst.afw.geom.testUtils.makeSipPolyMapCoeffs | ( | metadata, | |
| name | |||
| ) |
Return a list of ast.PolyMap coefficients for the specified SIP matrix
The returned list of coefficients for an ast.PolyMap
that computes the following function:
f(dxy) = dxy + sipPolynomial(dxy))
where dxy = pixelPosition - pixelOrigin
and sipPolynomial is a polynomial with terms `<name>n_m for x^n y^m`
(e.g. A2_0 is the coefficient for x^2 y^0)
Parameters
----------
metadata : lsst.daf.base.PropertySet
FITS metadata describing a WCS with the specified SIP coefficients
name : str
The desired SIP terms: one of A, B, AP, BP
Returns
-------
list
A list of coefficients for an ast.PolyMap that computes
the specified SIP polynomial, including a term for out = in
Note
----
This is an internal function for use by makeSipIwcToPixel
and makeSipPixelToIwc
Definition at line 141 of file testUtils.py.