Coverage for python/lsst/pipe/tasks/registerImage.py: 32%
80 statements
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1#
2# LSST Data Management System
3# Copyright 2008-2013 LSST Corporation.
4#
5# This product includes software developed by the
6# LSST Project (http://www.lsst.org/).
7#
8# This program is free software: you can redistribute it and/or modify
9# it under the terms of the GNU General Public License as published by
10# the Free Software Foundation, either version 3 of the License, or
11# (at your option) any later version.
12#
13# This program is distributed in the hope that it will be useful,
14# but WITHOUT ANY WARRANTY; without even the implied warranty of
15# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16# GNU General Public License for more details.
17#
18# You should have received a copy of the LSST License Statement and
19# the GNU General Public License along with this program. If not,
20# see <http://www.lsstcorp.org/LegalNotices/>.
21#
23"""
24This module contains a Task to register (align) multiple images.
25"""
26__all__ = ["RegisterTask", "RegisterConfig"]
28import math
29import numpy
31from lsst.pex.config import Config, Field, ConfigField
32from lsst.pipe.base import Task, Struct
33from lsst.meas.astrom.sip import makeCreateWcsWithSip
34from lsst.afw.math import Warper
36import lsst.geom as geom
37import lsst.afw.table as afwTable
40class RegisterConfig(Config):
41 """Configuration for RegisterTask"""
42 matchRadius = Field(dtype=float, default=1.0, doc="Matching radius (arcsec)", check=lambda x: x > 0)
43 sipOrder = Field(dtype=int, default=4, doc="Order for SIP WCS", check=lambda x: x > 1)
44 sipIter = Field(dtype=int, default=3, doc="Rejection iterations for SIP WCS", check=lambda x: x > 0)
45 sipRej = Field(dtype=float, default=3.0, doc="Rejection threshold for SIP WCS", check=lambda x: x > 0)
46 warper = ConfigField(dtype=Warper.ConfigClass, doc="Configuration for warping")
49class RegisterTask(Task):
50 """
51 Task to register (align) multiple images.
53 The 'run' method provides a revised Wcs from matches and fitting sources.
54 Additional methods are provided as a convenience to warp an exposure
55 ('warpExposure') and sources ('warpSources') with the new Wcs.
56 """
57 ConfigClass = RegisterConfig
59 def run(self, inputSources, inputWcs, inputBBox, templateSources):
60 """Register (align) an input exposure to the template
62 The sources must have RA,Dec set, and accurate to within the
63 'matchRadius' of the configuration in order to facilitate source
64 matching. We fit a new Wcs, but do NOT set it in the input exposure.
66 @param inputSources: Sources from input exposure
67 @param inputWcs: Wcs of input exposure
68 @param inputBBox: Bounding box of input exposure
69 @param templateSources: Sources from template exposure
70 @return Struct(matches: Matches between sources,
71 wcs: Wcs for input in frame of template,
72 )
73 """
74 matches = self.matchSources(inputSources, templateSources)
75 wcs = self.fitWcs(matches, inputWcs, inputBBox)
76 return Struct(matches=matches, wcs=wcs)
78 def matchSources(self, inputSources, templateSources):
79 """Match sources between the input and template
81 The order of the input arguments matters (because the later Wcs
82 fitting assumes a particular order).
84 @param inputSources: Source catalog of the input frame
85 @param templateSources: Source of the target frame
86 @return Match list
87 """
88 matches = afwTable.matchRaDec(templateSources, inputSources,
89 self.config.matchRadius*geom.arcseconds)
90 self.log.info("Matching within %.1f arcsec: %d matches", self.config.matchRadius, len(matches))
91 self.metadata["MATCH_NUM"] = len(matches)
92 if len(matches) == 0:
93 raise RuntimeError("Unable to match source catalogs")
94 return matches
96 def fitWcs(self, matches, inputWcs, inputBBox):
97 """Fit Wcs to matches
99 The fitting includes iterative sigma-clipping.
101 @param matches: List of matches (first is target, second is input)
102 @param inputWcs: Original input Wcs
103 @param inputBBox: Bounding box of input image
104 @return Wcs
105 """
106 copyMatches = type(matches)(matches)
107 refCoordKey = copyMatches[0].first.getTable().getCoordKey()
108 inCentroidKey = copyMatches[0].second.getTable().getCentroidSlot().getMeasKey()
109 for i in range(self.config.sipIter):
110 sipFit = makeCreateWcsWithSip(copyMatches, inputWcs, self.config.sipOrder, inputBBox)
111 self.log.debug("Registration WCS RMS iteration %d: %f pixels",
112 i, sipFit.getScatterInPixels())
113 wcs = sipFit.getNewWcs()
114 dr = [m.first.get(refCoordKey).separation(
115 wcs.pixelToSky(m.second.get(inCentroidKey))).asArcseconds() for
116 m in copyMatches]
117 dr = numpy.array(dr)
118 rms = math.sqrt((dr*dr).mean()) # RMS from zero
119 rms = max(rms, 1.0e-9) # Don't believe any RMS smaller than this
120 self.log.debug("Registration iteration %d: rms=%f", i, rms)
121 good = numpy.where(dr < self.config.sipRej*rms)[0]
122 numBad = len(copyMatches) - len(good)
123 self.log.debug("Registration iteration %d: rejected %d", i, numBad)
124 if numBad == 0:
125 break
126 copyMatches = type(matches)(copyMatches[i] for i in good)
128 sipFit = makeCreateWcsWithSip(copyMatches, inputWcs, self.config.sipOrder, inputBBox)
129 self.log.info("Registration WCS: final WCS RMS=%f pixels from %d matches",
130 sipFit.getScatterInPixels(), len(copyMatches))
131 self.metadata["SIP_RMS"] = sipFit.getScatterInPixels()
132 self.metadata["SIP_GOOD"] = len(copyMatches)
133 self.metadata["SIP_REJECTED"] = len(matches) - len(copyMatches)
134 wcs = sipFit.getNewWcs()
135 return wcs
137 def warpExposure(self, inputExp, newWcs, templateWcs, templateBBox):
138 """Warp input exposure to template frame
140 There are a variety of data attached to the exposure (e.g., PSF, PhotoCalib
141 and other metadata), but we do not attempt to warp these to the template
142 frame.
144 @param inputExp: Input exposure, to be warped
145 @param newWcs: Revised Wcs for input exposure
146 @param templateWcs: Target Wcs
147 @param templateBBox: Target bounding box
148 @return Warped exposure
149 """
150 warper = Warper.fromConfig(self.config.warper)
151 copyExp = inputExp.Factory(inputExp.getMaskedImage(), newWcs)
152 alignedExp = warper.warpExposure(templateWcs, copyExp, destBBox=templateBBox)
153 return alignedExp
155 def warpSources(self, inputSources, newWcs, templateWcs, templateBBox):
156 """Warp sources to the new frame
158 It would be difficult to transform all possible quantities of potential
159 interest between the two frames. We therefore update only the sky and
160 pixel coordinates.
162 @param inputSources: Sources on input exposure, to be warped
163 @param newWcs: Revised Wcs for input exposure
164 @param templateWcs: Target Wcs
165 @param templateBBox: Target bounding box
166 @return Warped sources
167 """
168 alignedSources = inputSources.copy(True)
169 if not isinstance(templateBBox, geom.Box2D):
170 # There is no method Box2I::contains(Point2D)
171 templateBBox = geom.Box2D(templateBBox)
172 table = alignedSources.getTable()
173 coordKey = table.getCoordKey()
174 centroidKey = table.getCentroidSlot().getMeasKey()
175 deleteList = []
176 for i, s in enumerate(alignedSources):
177 oldCentroid = s.get(centroidKey)
178 newCoord = newWcs.pixelToSky(oldCentroid)
179 newCentroid = templateWcs.skyToPixel(newCoord)
180 if not templateBBox.contains(newCentroid):
181 deleteList.append(i)
182 continue
183 s.set(coordKey, newCoord)
184 s.set(centroidKey, newCentroid)
186 for i in reversed(deleteList): # Delete from back so we don't change indices
187 del alignedSources[i]
189 return alignedSources