lsst.afw.cameraGeom._makePixelToTanPixel Namespace Reference
Functions | |
| makePixelToTanPixel (bbox, orientation, focalPlaneToField, pixelSizeMm) | |
Function Documentation
◆ makePixelToTanPixel()
| lsst.afw.cameraGeom._makePixelToTanPixel.makePixelToTanPixel | ( | bbox, | |
| orientation, | |||
| focalPlaneToField, | |||
| pixelSizeMm ) |
Make a Transform whose forward direction converts PIXELS to TAN_PIXELS
for one detector.
Parameters
----------
bbox : `lsst.geom.Box2I`
Detector bounding box.
orientation : `lsst.afw.cameraGeom.Orientation`
Orientation of detector in focal plane.
focalPlaneToField : `lsst.afw.geom.TransformPoint2ToPoint2`
A transform that converts from focal plane (mm) to field angle
coordinates (radians) in the forward direction.
pixelSizeMm : `lsst.geom.Extent2D`
Size of the pixel in mm in X and Y.
Returns
-------
transform : `lsst.afw.geom.TransformPoint2ToPoint2`
A transform whose forward direction converts PIXELS to TAN_PIXELS.
Notes
-----
PIXELS and TAN_PIXELS are described in the CameraGeom documentation under
:ref:`camera coordinate systems<section_Camera_Coordinate_Systems>`.
Definition at line 28 of file _makePixelToTanPixel.py.
28def makePixelToTanPixel(bbox, orientation, focalPlaneToField, pixelSizeMm):
29 """Make a Transform whose forward direction converts PIXELS to TAN_PIXELS
30 for one detector.
31
32 Parameters
33 ----------
34 bbox : `lsst.geom.Box2I`
35 Detector bounding box.
36 orientation : `lsst.afw.cameraGeom.Orientation`
37 Orientation of detector in focal plane.
38 focalPlaneToField : `lsst.afw.geom.TransformPoint2ToPoint2`
39 A transform that converts from focal plane (mm) to field angle
40 coordinates (radians) in the forward direction.
41 pixelSizeMm : `lsst.geom.Extent2D`
42 Size of the pixel in mm in X and Y.
43
44 Returns
45 -------
46 transform : `lsst.afw.geom.TransformPoint2ToPoint2`
47 A transform whose forward direction converts PIXELS to TAN_PIXELS.
48
49 Notes
50 -----
51 PIXELS and TAN_PIXELS are described in the CameraGeom documentation under
52 :ref:`camera coordinate systems<section_Camera_Coordinate_Systems>`.
53 """
54 pixelToFocalPlane = orientation.makePixelFpTransform(pixelSizeMm)
55 pixelToField = pixelToFocalPlane.then(focalPlaneToField)
56 # fieldToTanPix is affine and matches fieldToPix at field center
57 # Note: focal plane to field angle is typically a radial transform,
58 # and linearizing the inverse transform of that may fail,
59 # so linearize the forward direction instead. (pixelToField is pixelToFocalPlane,
60 # an affine transform, followed by focalPlaneToField,
61 # so the same consideration applies to pixelToField)
62 pixAtFieldCtr = pixelToField.applyInverse(lsst.geom.Point2D(0, 0))
63 tanPixToFieldAffine = lsst.afw.geom.linearizeTransform(pixelToField, pixAtFieldCtr)
64 fieldToTanPix = lsst.afw.geom.makeTransform(tanPixToFieldAffine.inverted())
65
66 return pixelToField.then(fieldToTanPix)
std::shared_ptr< TransformPoint2ToPoint2 > makeTransform(lsst::geom::AffineTransform const &affine)
Wrap an lsst::geom::AffineTransform as a Transform.
Definition transformFactory.cc:154
lsst::geom::AffineTransform linearizeTransform(TransformPoint2ToPoint2 const &original, lsst::geom::Point2D const &inPoint)
Approximate a Transform by its local linearization.
Definition transformFactory.cc:132
Generated on Thu Nov 27 2025 09:15:05 for LSST Applications by
1.13.2