Coverage for python/lsst/meas/algorithms/astrometrySourceSelector.py: 36%
58 statements
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« prev ^ index » next coverage.py v6.5.0, created at 2023-01-10 03:08 -0800
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"""Select sources that are useful for astrometry.
25Such sources have good signal-to-noise, are well centroided, not blended,
26and not flagged with a handful of "bad" flags.
27"""
29__all__ = ["AstrometrySourceSelectorConfig", "AstrometrySourceSelectorTask"]
31import numpy as np
33import lsst.pex.config as pexConfig
34from .sourceSelector import BaseSourceSelectorConfig, BaseSourceSelectorTask, sourceSelectorRegistry
35from lsst.pipe.base import Struct
36from functools import reduce
39class AstrometrySourceSelectorConfig(BaseSourceSelectorConfig):
40 badFlags = pexConfig.ListField(
41 doc="List of flags which cause a source to be rejected as bad",
42 dtype=str,
43 default=[
44 "base_PixelFlags_flag_edge",
45 "base_PixelFlags_flag_interpolatedCenter",
46 "base_PixelFlags_flag_saturatedCenter",
47 "base_PixelFlags_flag_crCenter",
48 "base_PixelFlags_flag_bad",
49 ],
50 )
51 sourceFluxType = pexConfig.Field(
52 doc="Type of source flux; typically one of Ap or Psf",
53 dtype=str,
54 default="Ap",
55 )
56 minSnr = pexConfig.Field(
57 dtype=float,
58 doc="Minimum allowed signal-to-noise ratio for sources used for matching "
59 "(in the flux specified by sourceFluxType); <= 0 for no limit",
60 default=10,
61 )
64@pexConfig.registerConfigurable("astrometry", sourceSelectorRegistry)
65class AstrometrySourceSelectorTask(BaseSourceSelectorTask):
66 """Select sources that are useful for astrometry.
68 Good astrometry sources have high signal/noise, are non-blended, and
69 did not have certain "bad" flags set during source extraction. They need not
70 be PSF sources, just have reliable centroids.
71 """
72 ConfigClass = AstrometrySourceSelectorConfig
74 def __init__(self, *args, **kwargs):
75 BaseSourceSelectorTask.__init__(self, *args, **kwargs)
77 def selectSources(self, sourceCat, matches=None, exposure=None):
78 """Return a selection of sources that are useful for astrometry.
80 Parameters
81 ----------
82 sourceCat : `lsst.afw.table.SourceCatalog`
83 Catalog of sources to select from.
84 This catalog must be contiguous in memory.
85 matches : `list` of `lsst.afw.table.ReferenceMatch` or None
86 Ignored in this SourceSelector.
87 exposure : `lsst.afw.image.Exposure` or None
88 The exposure the catalog was built from; used for debug display.
90 Returns
91 -------
92 struct : `lsst.pipe.base.Struct`
93 The struct contains the following data:
95 ``selected``
96 Boolean array of sources that were selected, same length as
97 sourceCat. (`numpy.ndarray` of `bool`)
98 """
99 self._getSchemaKeys(sourceCat.schema)
101 bad = reduce(lambda x, y: np.logical_or(x, sourceCat.get(y)), self.config.badFlags, False)
102 good = self._isGood(sourceCat)
103 return Struct(selected=good & ~bad)
105 def _getSchemaKeys(self, schema):
106 """Extract and save the necessary keys from schema with asKey.
107 """
108 self.parentKey = schema["parent"].asKey()
109 self.nChildKey = schema["deblend_nChild"].asKey()
110 self.centroidXKey = schema["slot_Centroid_x"].asKey()
111 self.centroidYKey = schema["slot_Centroid_y"].asKey()
112 self.centroidXErrKey = schema["slot_Centroid_xErr"].asKey()
113 self.centroidYErrKey = schema["slot_Centroid_yErr"].asKey()
114 self.centroidFlagKey = schema["slot_Centroid_flag"].asKey()
116 self.edgeKey = schema["base_PixelFlags_flag_edge"].asKey()
117 self.interpolatedCenterKey = schema["base_PixelFlags_flag_interpolatedCenter"].asKey()
118 self.saturatedKey = schema["base_PixelFlags_flag_saturated"].asKey()
120 fluxPrefix = "slot_%sFlux_" % (self.config.sourceFluxType,)
121 self.instFluxKey = schema[fluxPrefix + "instFlux"].asKey()
122 self.fluxFlagKey = schema[fluxPrefix + "flag"].asKey()
123 self.instFluxErrKey = schema[fluxPrefix + "instFluxErr"].asKey()
125 def _isMultiple(self, sourceCat):
126 """Return True for each source that is likely multiple sources.
127 """
128 test = (sourceCat.get(self.parentKey) != 0) | (sourceCat.get(self.nChildKey) != 0)
129 # have to currently manage footprints on a source-by-source basis.
130 for i, cat in enumerate(sourceCat):
131 footprint = cat.getFootprint()
132 test[i] |= (footprint is not None) and (len(footprint.getPeaks()) > 1)
133 return test
135 def _hasCentroid(self, sourceCat):
136 """Return True for each source that has a valid centroid
137 """
138 def checkNonfiniteCentroid():
139 """Return True for sources with non-finite centroids.
140 """
141 return ~np.isfinite(sourceCat.get(self.centroidXKey)) | \
142 ~np.isfinite(sourceCat.get(self.centroidYKey))
143 assert ~checkNonfiniteCentroid().any(), \
144 "Centroids not finite for %d unflagged sources." % (checkNonfiniteCentroid().sum())
145 return np.isfinite(sourceCat.get(self.centroidXErrKey)) \
146 & np.isfinite(sourceCat.get(self.centroidYErrKey)) \
147 & ~sourceCat.get(self.centroidFlagKey)
149 def _goodSN(self, sourceCat):
150 """Return True for each source that has Signal/Noise > config.minSnr.
151 """
152 if self.config.minSnr <= 0:
153 return True
154 else:
155 with np.errstate(invalid="ignore"): # suppress NAN warnings
156 return sourceCat.get(self.instFluxKey)/sourceCat.get(self.instFluxErrKey) > self.config.minSnr
158 def _isUsable(self, sourceCat):
159 """Return True for each source that is usable for matching, even if it may
160 have a poor centroid.
162 For a source to be usable it must:
163 - have a valid centroid
164 - not be deblended
165 - have a valid flux (of the type specified in this object's constructor)
166 - have adequate signal-to-noise
167 """
169 return self._hasCentroid(sourceCat) \
170 & ~self._isMultiple(sourceCat) \
171 & self._goodSN(sourceCat) \
172 & ~sourceCat.get(self.fluxFlagKey)
174 def _isGood(self, sourceCat):
175 """Return True for each source that is usable for matching and likely has a
176 good centroid.
178 The additional tests for a good centroid, beyond isUsable, are:
179 - not interpolated in the center
180 - not saturated
181 - not near the edge
182 """
184 return self._isUsable(sourceCat) \
185 & ~sourceCat.get(self.saturatedKey) \
186 & ~sourceCat.get(self.interpolatedCenterKey) \
187 & ~sourceCat.get(self.edgeKey)
189 def _isBadFlagged(self, source):
190 """Return True if any of config.badFlags are set for this source.
191 """
192 return any(source.get(flag) for flag in self.config.badFlags)