lsst.meas.extensions.trailedSources geebf31c2e0+99e7a5c2d8
VeresPlugin.py
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2# This file is part of meas_extensions_trailedSources.
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23
24import numpy as np
25import scipy.optimize as sciOpt
26
27from lsst.pex.config import Field
28
29from lsst.meas.base.pluginRegistry import register
30from lsst.meas.base import SingleFramePlugin, SingleFramePluginConfig
31from lsst.meas.base import FlagHandler, FlagDefinitionList, SafeCentroidExtractor
32from lsst.meas.base import MeasurementError
33
34from ._trailedSources import VeresModel
35from .NaivePlugin import SingleFrameNaiveTrailPlugin
36
37__all__ = ("SingleFrameVeresTrailConfig", "SingleFrameVeresTrailPlugin")
38
39
40class SingleFrameVeresTrailConfig(SingleFramePluginConfig):
41 """Config class for SingleFrameVeresTrailPlugin
42 """
43
44 optimizerMethod = Field(
45 doc="Optimizer method for scipy.optimize.minimize",
46 dtype=str,
47 default="L-BFGS-B"
48 )
49
50
51@register("ext_trailedSources_Veres")
52class SingleFrameVeresTrailPlugin(SingleFramePlugin):
53 """Veres trailed source characterization plugin.
54
55 Measures the length, angle, flux, centroid, and end points of a trailed
56 source using the Veres et al. 2012 model [1]_.
57
58 Parameters
59 ----------
60 config: `SingleFrameNaiveTrailConfig`
61 Plugin configuration.
62 name: `str`
63 Plugin name.
64 schema: `lsst.afw.table.Schema`
65 Schema for the output catalog.
67 Metadata to be attached to output catalog.
68
69 Notes
70 -----
71 This plugin is designed to refine the measurements of trail length,
72 angle, and end points from `NaivePlugin`, and of flux and centroid from
73 previous measurement algorithms. Vereš et al. 2012 [1]_ derive a model for
74 the flux in a given image pixel by convolving an axisymmetric Gaussian with
75 a line. The model is parameterized by the total flux, trail length, angle
76 from the x-axis, and the centroid. The best estimates are computed using a
77 chi-squared minimization.
78
79 References
80 ----------
81 .. [1] Vereš, P., et al. "Improved Asteroid Astrometry and Photometry with
82 Trail Fitting" PASP, vol. 124, 2012.
83
84 See also
85 --------
86 lsst.meas.base.SingleFramePlugin
87 """
88
89 ConfigClass = SingleFrameVeresTrailConfig
90
91 @classmethod
93 # Needs centroids, shape, flux, and NaivePlugin measurements.
94 # Make sure this always runs after NaivePlugin.
95 return SingleFrameNaiveTrailPlugin.getExecutionOrder() + 0.1
96
97 def __init__(self, config, name, schema, metadata):
98 super().__init__(config, name, schema, metadata)
99
100 self.keyXCkeyXC = schema.addField(
101 name + "_centroid_x", type="D", doc="Trail centroid X coordinate.", units="pixel")
102 self.keyYCkeyYC = schema.addField(
103 name + "_centroid_y", type="D", doc="Trail centroid Y coordinate.", units="pixel")
104 self.keyX0keyX0 = schema.addField(name + "_x0", type="D", doc="Trail head X coordinate.", units="pixel")
105 self.keyY0keyY0 = schema.addField(name + "_y0", type="D", doc="Trail head Y coordinate.", units="pixel")
106 self.keyX1keyX1 = schema.addField(name + "_x1", type="D", doc="Trail tail X coordinate.", units="pixel")
107 self.keyY1keyY1 = schema.addField(name + "_y1", type="D", doc="Trail tail Y coordinate.", units="pixel")
108 self.keyLkeyL = schema.addField(name + "_length", type="D", doc="Length of trail.", units="pixel")
109 self.keyThetakeyTheta = schema.addField(name + "_angle", type="D", doc="Angle of trail from +x-axis.")
110 self.keyFluxkeyFlux = schema.addField(name + "_flux", type="D", doc="Trailed source flux.", units="count")
111 self.keyRChiSqkeyRChiSq = schema.addField(name + "_rChiSq", type="D", doc="Reduced chi-squared of fit")
112
113 flagDefs = FlagDefinitionList()
114 flagDefs.addFailureFlag("No trailed-sources measured")
115 self.NON_CONVERGENON_CONVERGE = flagDefs.add("flag_nonConvergence", "Optimizer did not converge")
116 self.NO_NAIVENO_NAIVE = flagDefs.add("flag_noNaive", "Naive measurement contains NaNs")
117 self.flagHandlerflagHandler = FlagHandler.addFields(schema, name, flagDefs)
118
119 self.centroidExtractorcentroidExtractor = SafeCentroidExtractor(schema, name)
120
121 def measure(self, measRecord, exposure):
122 """Run the Veres trailed source measurement plugin.
123
124 Parameters
125 ----------
126 measRecord : `lsst.afw.table.SourceRecord`
127 Record describing the object being measured.
128 exposure : `lsst.afw.image.Exposure`
129 Pixel data to be measured.
130
131 See also
132 --------
133 lsst.meas.base.SingleFramePlugin.measure
134 """
135 xc, yc = self.centroidExtractorcentroidExtractor(measRecord, self.flagHandlerflagHandler)
136
137 # Look at measRecord for Naive measurements
138 # ASSUMES NAIVE ALREADY RAN
139 F = measRecord.get("ext_trailedSources_Naive_flux")
140 L = measRecord.get("ext_trailedSources_Naive_length")
141 theta = measRecord.get("ext_trailedSources_Naive_angle")
142 if not np.isfinite(F) or not np.isfinite(L) or not np.isfinite(theta):
143 raise MeasurementError(self.NO_NAIVENO_NAIVE.doc, self.NO_NAIVENO_NAIVE.number)
144
145 # Make VeresModel
146 model = VeresModel(exposure)
147
148 # Do optimization with scipy
149 params = np.array([xc, yc, F, L, theta])
150 results = sciOpt.minimize(
151 model, params, method=self.config.optimizerMethod, jac=model.gradient)
152
153 # Check if optimizer converged
154 if not results.success:
155 raise MeasurementError(self.NON_CONVERGENON_CONVERGE.doc, self.NON_CONVERGENON_CONVERGE.number)
156
157 # Calculate end points and reduced chi-squared
158 xc_fit, yc_fit, F_fit, L_fit, theta_fit = results.x
159 a = L_fit/2
160 x0_fit = xc_fit - a * np.cos(theta_fit)
161 y0_fit = yc_fit - a * np.sin(theta_fit)
162 x1_fit = xc_fit + a * np.cos(theta_fit)
163 y1_fit = yc_fit + a * np.sin(theta_fit)
164 rChiSq = results.fun / (exposure.image.array.size - 6)
165
166 # Set keys
167 measRecord.set(self.keyXCkeyXC, xc_fit)
168 measRecord.set(self.keyYCkeyYC, yc_fit)
169 measRecord.set(self.keyX0keyX0, x0_fit)
170 measRecord.set(self.keyY0keyY0, y0_fit)
171 measRecord.set(self.keyX1keyX1, x1_fit)
172 measRecord.set(self.keyY1keyY1, y1_fit)
173 measRecord.set(self.keyFluxkeyFlux, F_fit)
174 measRecord.set(self.keyLkeyL, L_fit)
175 measRecord.set(self.keyThetakeyTheta, theta_fit)
176 measRecord.set(self.keyRChiSqkeyRChiSq, rChiSq)
177
178 def fail(self, measRecord, error=None):
179 """Record failure
180
181 See also
182 --------
183 lsst.meas.base.SingleFramePlugin.fail
184 """
185 if error is None:
186 self.flagHandlerflagHandler.handleFailure(measRecord)
187 else:
188 self.flagHandlerflagHandler.handleFailure(measRecord, error.cpp)