Coverage for python/lsst/jointcal/cameraGeometry.py: 17%
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1# This file is part of jointcal.
2#
3# Developed for the LSST Data Management System.
4# This product includes software developed by the LSST Project
5# (https://www.lsst.org).
6# See the COPYRIGHT file at the top-level directory of this distribution
7# for details of code ownership.
8#
9# This program is free software: you can redistribute it and/or modify
10# it under the terms of the GNU General Public License as published by
11# the Free Software Foundation, either version 3 of the License, or
12# (at your option) any later version.
13#
14# This program is distributed in the hope that it will be useful,
15# but WITHOUT ANY WARRANTY; without even the implied warranty of
16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17# GNU General Public License for more details.
18#
19# You should have received a copy of the GNU General Public License
20# along with this program. If not, see <https://www.gnu.org/licenses/>.
22"""Code to convert jointcal's output WCS models to distortion maps that can be
23used by afw CameraGeom.
24"""
25import numpy as np
27from lsst.afw import cameraGeom
28import lsst.afw.geom
29import astshim as ast
30import lsst.log
31from lsst.geom import SpherePoint, Point2D, radians
33_LOG = lsst.log.Log.getLogger(__name__)
36class CameraModel:
37 """Convert a jointcal `~lsst.afw.geom.SkyWcs` into a distortion model and
38 detector positions (TODO) that can be used by `~lsst.afw.cameraGeom`.
40 Because this code only operates on the WCS, it is independent of the
41 format of the persisted output (e.g. gen2 separate files vs. gen3 bundled
42 visits).
44 Parameters
45 ----------
46 wcsList : `list` [`lsst.afw.geom.SkyWcs`]
47 The WCS to use to compute the distortion model from, preferably from
48 multiple visits on the same tract.
49 detectors : `list` [`int`]
50 Detector ids that correspond one-to-one with ``wcsList``.
51 camera : `lsst.afw.cameraGeom.Camera`
52 The camera these WCS were fit for.
53 n : `int`
54 Number of points to compute the pixel scale at, along the +y axis.
55 """
56 def __init__(self, wcsList, detectors, camera, n=100):
57 self.wcsList = wcsList
58 self.camera = camera
59 self.detectors = detectors
60 self.maxFocalRadius = self.camera.computeMaxFocalPlaneRadius()
61 self.n = n
62 # the computed radius and pixel scales
63 self.fieldAngle = None # degrees
64 self.radialScale = None # arcsec
65 self.tangentialScale = None # arcsec
66 # the computed values for every input wcs
67 self.fieldAngles = None
68 self.radialScales = None
69 self.tangentialScales = None
70 self.fieldAngleStd = None
71 self.radialScaleStd = None
72 self.tangentialScaleStd = None
74 self.log = _LOG.getChild("CameraModel")
76 def computeDistortionModel(self):
77 """Calculate the afw cameraGeom distortion model to be included in an
78 on-disk camera model.
81 PLACEHOLDER: This may be as simple as running `computePixelScale` and
82 then doing a numpy polynomial fit to it for the cameraGeom input.
83 However, we need to check details of how that distortion model is
84 stored in a Camera.
85 e.g.: np.polyfit(self.fieldAngle, self.radialScale, poly_degree))
86 """
87 raise NotImplementedError("not yet!")
89 def computePixelScale(self):
90 """Compute the radial and tangential pixel scale by averaging over
91 multiple jointcal WCS models.
93 Also computes the standard deviation and logs any WCS that are
94 significant outliers.
95 The calculations are stored in the ``fieldAngle[s]``,
96 ``radialScale[s]``, and ``tangentialScale[s]`` member variables.
97 """
98 self.fieldAngles = []
99 self.radialScales = []
100 self.tangentialScales = []
101 for id, wcs in zip(self.detectors, self.wcsList):
102 fieldAngle, radial, tangential = self._computeDetectorPixelScale(id, wcs)
103 self.fieldAngles.append(fieldAngle)
104 self.radialScales.append(radial)
105 self.tangentialScales.append(tangential)
106 # TODO: For now, don't worry about small differences in the computed
107 # field angles vs. their respective radial/tangential scales, just
108 # assume all fieldAngle positions are "close enough" and warn if not.
109 self.fieldAngle = np.mean(self.fieldAngles, axis=0)
110 self.fieldAngleStd = np.std(self.fieldAngles, axis=0)
111 if self.fieldAngleStd.max() > 1e-4:
112 self.log.warning("Large stddev in computed field angles between visits (max: %s degree).",
113 self.fieldAngleStd.max())
114 # import os; print(os.getpid()); import ipdb; ipdb.set_trace();
115 self.radialScale = np.mean(self.radialScales, axis=0)
116 self.radialScaleStd = np.std(self.radialScales, axis=0)
117 if self.radialScaleStd.max() > 1e-4:
118 self.log.warning("Large stddev in computed radial scales between visits (max: %s arcsec).",
119 self.radialScaleStd.max())
120 self.tangentialScale = np.mean(self.tangentialScales, axis=0)
121 self.tangentialScaleStd = np.std(self.tangentialScales, axis=0)
122 if self.tangentialScaleStd.max() > 1e-4:
123 self.log.warning("Large stddev in computed tangential scales between visits (max: %s arcsec).",
124 self.tangentialScaleStd.max())
126 def computeCameraPixelScale(self, detector_id=30):
127 """Compute the radial and tangential pixel scales using the distortion
128 model supplied with the camera.
130 This is designed to be directly comparable with the results of
131 `~CameraModel.computePixelScale`.
133 Parameters
134 ----------
135 detector_id: `int`
136 Detector identifier for the detector_id to use for the calculation.
138 Returns
139 -------
140 fieldAngle : `numpy.ndarray`
141 Field angles in degrees.
142 radialScale : `numpy.ndarray`
143 Radial direction pixel scales in arcseconds/pixel.
144 tangentialScale : `numpy.ndarray`
145 Tangential direction pixel scales in arcseconds/pixel.
146 """
147 # Make a trivial SkyWcs to get a field angle->sky transform from.
148 iwcToSkyWcs = lsst.afw.geom.makeSkyWcs(Point2D(0, 0), SpherePoint(0, 0, radians),
149 lsst.afw.geom.makeCdMatrix(1.0 * radians, 0 * radians, True))
150 iwcToSkyMap = iwcToSkyWcs.getFrameDict().getMapping("PIXELS", "SKY")
151 skyFrame = iwcToSkyWcs.getFrameDict().getFrame("SKY")
153 # Extract the transforms that are defined just on the camera.
154 pixSys = self.camera[detector_id].makeCameraSys(cameraGeom.PIXELS)
155 pixelsToFocal = self.camera.getTransform(pixSys, cameraGeom.FOCAL_PLANE)
156 focalToField = self.camera.getTransform(cameraGeom.FOCAL_PLANE, cameraGeom.FIELD_ANGLE)
158 # Build a SkyWcs that combines each of the above components.
159 pixelFrame = ast.Frame(2, "Domain=PIXELS")
160 focalFrame = ast.Frame(2, "Domain=FOCAL")
161 iwcFrame = ast.Frame(2, "Domain=IWC")
162 frameDict = ast.FrameDict(pixelFrame)
163 frameDict.addFrame("PIXELS", pixelsToFocal.getMapping(), focalFrame)
164 frameDict.addFrame("FOCAL", focalToField.getMapping(), iwcFrame)
165 frameDict.addFrame("IWC", iwcToSkyMap, skyFrame)
166 wcs = lsst.afw.geom.SkyWcs(frameDict)
168 return self._computeDetectorPixelScale(detector_id, wcs)
170 def _computeDetectorPixelScale(self, detector_id, wcs):
171 """Compute pixel scale in radial and tangential directions as a
172 function of field angle.
174 Parameters
175 ----------
176 detector_id: `int`
177 Detector identifier for the detector of this wcs.
178 wcs : `lsst.afw.geom.SkyWcs`
179 Full focal-plane model to compute pixel scale on.
181 Returns
182 -------
183 fieldAngle : `numpy.ndarray`
184 Field angles in degrees.
185 radialScale : `numpy.ndarray`
186 Radial direction pixel scales in arcseconds/pixel.
187 tangentialScale : `numpy.ndarray`
188 Tangential direction pixel scales in arcseconds/pixel.
190 Notes
191 -----
192 Pixel scales are calculated from finite differences only along the +y
193 focal plane direction.
194 """
195 focalToSky = wcs.getFrameDict().getMapping('FOCAL', 'SKY')
196 mmPerPixel = self.camera[detector_id].getPixelSize()
198 focalToPixels = wcs.getFrameDict().getMapping('FOCAL', 'PIXELS')
199 trans = wcs.getTransform() # Pixels to Sky as Point2d -> SpherePoint
200 boresight = trans.applyForward(Point2D(focalToPixels.applyForward([0, 0])))
202 rs = np.linspace(0, self.maxFocalRadius, self.n) # focal plane units
203 fieldAngle = np.zeros_like(rs)
204 radialScale = np.zeros_like(rs)
205 tangentialScale = np.zeros_like(rs)
206 for i, r in enumerate(rs):
207 # point on the sky at position r along the focal plane +y axis
208 sp1 = SpherePoint(*focalToSky.applyForward(Point2D([0, r])), radians)
209 # point on the sky one pixel further along the focal plane +y axis
210 sp2 = SpherePoint(*focalToSky.applyForward(Point2D([0, r + mmPerPixel.getY()])), radians)
211 # point on the sky one pixel off of the focal plane +y axis at r
212 sp3 = SpherePoint(*focalToSky.applyForward(Point2D([mmPerPixel.getX(), r])), radians)
213 fieldAngle[i] = boresight.separation(sp1).asDegrees()
214 radialScale[i] = sp1.separation(sp2).asArcseconds()
215 tangentialScale[i] = sp1.separation(sp3).asArcseconds()
216 return fieldAngle, radialScale, tangentialScale