Coverage for python/lsst/meas/algorithms/installGaussianPsf.py : 42%

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1#
2# LSST Data Management System
3#
4# Copyright 2008-2017 AURA/LSST.
5#
6# This product includes software developed by the
7# LSST Project (http://www.lsst.org/).
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 LSST License Statement and
20# the GNU General Public License along with this program. If not,
21# see <https://www.lsstcorp.org/LegalNotices/>.
22#
23__all__ = ["InstallGaussianPsfConfig", "InstallGaussianPsfTask"]
25import math
27import lsst.pex.config as pexConfig
28import lsst.pipe.base as pipeBase
29from lsst.meas.algorithms import SingleGaussianPsf
31FwhmPerSigma = 2.0*math.sqrt(2.0*math.log(2.0))
34class InstallGaussianPsfConfig(pexConfig.Config):
35 """!Config for InstallGaussianPsfTask"""
36 fwhm = pexConfig.Field(
37 dtype=float,
38 default=1.5 * FwhmPerSigma,
39 doc="Estimated FWHM of simple Gaussian PSF model, in pixels. "
40 "Ignored if input exposure has a PSF model."
41 )
42 width = pexConfig.RangeField(
43 dtype=int,
44 doc="Width and height of PSF model, in pixels. Must be odd.",
45 default=11,
46 min=1,
47 )
49 def validate(self):
50 if self.width % 2 == 0:
51 raise RuntimeError("width=%s must be odd" % (self.width,))
54## @addtogroup LSST_task_documentation
55## @{
56## @page InstallGaussianPsfTask
57## @ref InstallGaussianPsfTask_ "InstallGaussianPsfTask"
58## @copybrief InstallGaussianPsfTask
59## @}
61class InstallGaussianPsfTask(pipeBase.Task):
62 r"""!Install a Gaussian PSF model in an exposure
64 @anchor InstallGaussianPsfTask_
66 @section pipe_tasks_installGaussianPsf_Contents Contents
68 - @ref pipe_tasks_installGaussianPsf_Purpose
69 - @ref pipe_tasks_installGaussianPsf_Initialize
70 - @ref pipe_tasks_installGaussianPsf_IO
71 - @ref pipe_tasks_installGaussianPsf_Config
72 - @ref pipe_tasks_installGaussianPsf_Metadata
73 - @ref pipe_tasks_installGaussianPsf_Debug
74 - @ref pipe_tasks_installGaussianPsf_Example
76 @section pipe_tasks_installGaussianPsf_Purpose Description
78 Install a Gaussian PSF model in an exposure.
79 If the exposure already has a PSF model then the new model
80 has the same sigma and size (width and height in pixels) of the existing model.
81 If the exposure does not have a PSF model then the PSF sigma and size
82 are taken from the config.
84 At present the produced model is always circularly symmetric, but it is planned
85 to change this to an elliptical PSF model (only for the case that the exposure
86 already has a PSF model), once the necessary PSF object is available.
88 A variant of this task may someday exist to estimate the PSF
89 from the pixel data if no PSF model is present.
91 @section pipe_tasks_installGaussianPsf_Initialize Task initialisation
93 @copydoc \_\_init\_\_
95 @section pipe_tasks_installGaussianPsf_IO Invoking the Task
97 The main method is `run`.
99 @section pipe_tasks_installGaussianPsf_Config Configuration parameters
101 See @ref InstallGaussianPsfConfig
103 @section pipe_tasks_installGaussianPsf_Debug Debug variables
105 This task has no debug display
107 @section pipe_tasks_installGaussianPsf_Example A complete example of using InstallGaussianPsfTask
109 from lsst.afw.image import ExposureF
110 from lsst.meas.algorithms.installGaussianPsf import InstallGaussianPsfTask, FwhmPerSigma
112 exposure = ExposureF(100, 100)
113 task = InstallGaussianPsfTask()
114 task.run(exposure=exposure)
116 # This particular exposure had no PSF model to begin with, so the new PSF model
117 # uses the config's FWHM. However, measured FWHM is based on the truncated
118 # PSF image, so it does not exactly match the input
119 measFwhm = exposure.getPsf().computeShape().getDeterminantRadius() * FwhmPerSigma
120 assert abs(measFwhm - task.config.fwhm) < 1e-3
121 """
122 ConfigClass = InstallGaussianPsfConfig
123 _DefaultName = "installSimplePsfModel"
125 def run(self, exposure):
126 """!Set exposure's PSF to a simple PSF model
128 The sigma and width of the new simple PSF model matches the sigma and width of the current model,
129 if any, else the config parameters are used.
131 @param[in,out] exposure exposure to which to replace or add the PSF model
132 """
133 if exposure.hasPsf():
134 psfModel = exposure.getPsf()
135 psfSigma = psfModel.computeShape().getDeterminantRadius()
136 width, height = psfModel.computeImage().getDimensions()
137 else:
138 psfSigma = self.config.fwhm / FwhmPerSigma
139 width = height = self.config.width
141 if psfSigma <= 0:
142 raise RuntimeError("psfSigma = %s <= 0" % (psfSigma,))
144 self.log.debug("installing a simple Gaussian PSF model with width=%s, height=%s, FWHM=%0.3f",
145 width, height, psfSigma*FwhmPerSigma)
146 psfModel = SingleGaussianPsf(width, height, psfSigma)
147 exposure.setPsf(psfModel)