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LSST Data Management Base Package
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makePsfCandidates.py
Go to the documentation of this file.
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__ = ["MakePsfCandidatesConfig", "MakePsfCandidatesTask"]
24
25import numpy as np
26
27from lsst.afw.table import SourceCatalog
28import lsst.afw.math as afwMath
29import lsst.pex.config as pexConfig
31import lsst.pipe.base as pipeBase
32from . import makePsfCandidate
33
34
35class MakePsfCandidatesConfig(pexConfig.Config):
36 kernelSize = pexConfig.Field[int](
37 doc="Size of the postage stamp in pixels (excluding the border) around each star that is extracted "
38 "for fitting. Should be odd and preferably at least 25.",
39 default=25,
40 )
41 borderWidth = pexConfig.Field[int](
42 doc="Number of pixels to ignore around the edge of PSF candidate postage stamps",
43 default=0,
44 )
45
46
47class MakePsfCandidatesTask(pipeBase.Task):
48 """Create PSF candidates given an input catalog.
49 """
50 ConfigClass = MakePsfCandidatesConfig
51 _DefaultName = "makePsfCandidates"
52
53 def run(self, starCat, exposure, psfCandidateField=None):
54 """Make a list of PSF candidates from a star catalog.
55
56 Parameters
57 ----------
58 starCat : `lsst.afw.table.SourceCatalog`
59 Catalog of stars, as returned by
60 ``lsst.meas.algorithms.starSelector.run()``.
61 exposure : `lsst.afw.image.Exposure`
62 The exposure containing the sources.
63 psfCandidateField : `str`, optional
64 Name of flag field to set True for PSF candidates, or None to not
65 set a field; the field is left unchanged for non-candidates.
66
67 Returns
68 -------
69 struct : `lsst.pipe.base.Struct`
70 Results struct containing:
71
72 - ``psfCandidates`` : List of PSF candidates
73 (`list` of `lsst.meas.algorithms.PsfCandidate`).
74 - ``goodStarCat`` : Subset of ``starCat`` that was successfully made
75 into PSF candidates (`lsst.afw.table.SourceCatalog`).
76
77 """
78 psfResult = self.makePsfCandidates(starCat, exposure)
79
80 if psfCandidateField is not None:
81 isStarKey = starCat.schema[psfCandidateField].asKey()
82 for star in psfResult.goodStarCat:
83 star.set(isStarKey, True)
84
85 return psfResult
86
87 def makePsfCandidates(self, starCat, exposure):
88 """Make a list of PSF candidates from a star catalog.
89
90 Parameters
91 ----------
92 starCat : `lsst.afw.table.SourceCatalog`
93 Catalog of stars, as returned by
94 ``lsst.meas.algorithms.starSelector.run()``.
95 exposure : `lsst.afw.image.Exposure`
96 The exposure containing the sources.
97
98 Returns
99 -------
100 struct : `lsst.pipe.base.Struct`
101 Results struct containing:
102
103 - ``psfCandidates`` : List of PSF candidates
104 (`list` of `lsst.meas.algorithms.PsfCandidate`).
105 - ``goodStarCat`` : Subset of ``starCat`` that was successfully made
106 into PSF candidates (`lsst.afw.table.SourceCatalog`).
107 """
108 goodStarCat = SourceCatalog(starCat.schema)
109
110 psfCandidateList = []
111 didSetSize = False
112 for star in starCat:
113 psfCandidate = makePsfCandidate(star, exposure)
114 try:
115 psfCandidate.setPsfColorValue(star['psf_color_value'])
116 psfCandidate.setPsfColorType(star['psf_color_type'])
117 except Exception:
118 psfCandidate.setPsfColorValue(np.nan)
119 psfCandidate.setPsfColorType("")
120 try:
121 # The setXXX methods are class static, but it's convenient to call them on
122 # an instance as we don't know exposures's pixel type
123 # (and hence psfCandidate's exact type)
124 if not didSetSize:
125 psfCandidate.setBorderWidth(self.config.borderWidth)
126 psfCandidate.setWidth(self.config.kernelSize + 2*self.config.borderWidth)
127 psfCandidate.setHeight(self.config.kernelSize + 2*self.config.borderWidth)
128 didSetSize = True
129
130 im = psfCandidate.getMaskedImage().getImage()
132 self.log.warning("Could not get stamp for psfCandidate with source id=%s: %s",
133 star.getId(), psfCandidate)
134 continue
136 self.log.error("%s raised making psfCandidate from source id=%s: %s",
137 e.__class__.__name__, star.getId(), psfCandidate)
138 self.log.error("psfCandidate exception: %s", e)
139 continue
140
141 vmax = afwMath.makeStatistics(im, afwMath.MAX).getValue()
142 if not np.isfinite(vmax):
143 continue
144 if 'psf_max_value' in star.schema:
145 star['psf_max_value'] = vmax
146 psfCandidateList.append(psfCandidate)
147 goodStarCat.append(star)
148
149 return pipeBase.Struct(
150 psfCandidates=psfCandidateList,
151 goodStarCat=goodStarCat,
152 )
run(self, starCat, exposure, psfCandidateField=None)
Provides consistent interface for LSST exceptions.
Definition Exception.h:107
Reports attempts to exceed implementation-defined length limits for some classes.
Definition Runtime.h:76
Statistics makeStatistics(lsst::afw::image::Image< Pixel > const &img, lsst::afw::image::Mask< image::MaskPixel > const &msk, int const flags, StatisticsControl const &sctrl=StatisticsControl())
Handle a watered-down front-end to the constructor (no variance)
Definition Statistics.h:361
std::shared_ptr< PsfCandidate< PixelT > > makePsfCandidate(std::shared_ptr< afw::table::SourceRecord > const &source, std::shared_ptr< afw::image::Exposure< PixelT > > image)
Return a PsfCandidate of the right sort.