lsst.afw g5a732f18d5+53520f316c
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wcsUtils.cc
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1// -*- lsst-c++ -*-
2
3/*
4 * LSST Data Management System
5 * Copyright 2018 LSST Corporation.
6 *
7 * This product includes software developed by the
8 * LSST Project (http://www.lsst.org/).
9 *
10 * This program is free software: you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation, either version 3 of the License, or
13 * (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
19 *
20 * You should have received a copy of the LSST License Statement and
21 * the GNU General Public License along with this program. If not,
22 * see <http://www.lsstcorp.org/LegalNotices/>.
23 */
24
25#include <cmath>
26#include <memory>
27#include <vector>
28
29#include "lsst/afw/table/fwd.h"
34
35namespace lsst {
36namespace afw {
37namespace table {
38namespace {
39
40// Get the schema from a record
41Schema getSchema(BaseRecord const &record) { return record.getSchema(); }
42
43// Get the schema from a shared pointer to a record
44Schema getSchema(std::shared_ptr<const BaseRecord> const record) { return record->getSchema(); }
45
46// Get a value from a record
47template <typename Key>
48inline typename Key::Value getValue(BaseRecord const &record, Key const &key) {
49 return record.get(key);
50}
51
52// Get a value from a shared pointer to a record
53template <typename Key>
54inline typename Key::Value getValue(std::shared_ptr<const BaseRecord> const record, Key const &key) {
55 return record->get(key);
56}
57
58// Set a value in a record
59template <typename Key>
60inline void setValue(SimpleRecord &record, Key const &key, typename Key::Value const &value) {
61 record.set(key, value);
62}
63
64// Set a value in a shared pointer to a record
65template <typename Key>
66inline void setValue(std::shared_ptr<SimpleRecord> record, Key const &key, typename Key::Value const &value) {
67 record->set(key, value);
68}
69
70} // namespace
71
72template <typename ReferenceCollection>
74 if (refList.empty()) {
75 return;
76 }
77 auto const schema = getSchema(refList[0]);
78 CoordKey const coordKey(schema["coord"]);
79 Point2DKey const centroidKey(schema["centroid"]);
80 Key<Flag> const hasCentroidKey(schema["hasCentroid"]);
82 skyList.reserve(refList.size());
83 for (auto const &record : refList) {
84 skyList.emplace_back(getValue(record, coordKey));
85 }
87 auto pixelPos = pixelList.cbegin();
88 for (auto &refObj : refList) {
89 setValue(refObj, centroidKey, *pixelPos);
90 setValue(refObj, hasCentroidKey, true);
91 ++pixelPos;
92 }
93}
94
96 Eigen::Matrix2f err) {
97 if (!std::isfinite(center.getX()) || !std::isfinite(center.getY())) {
98 return Eigen::Matrix2f::Constant(NAN);
99 }
100 // Get the derivative of the pixel-to-sky transformation, then use it to
101 // propagate the centroid uncertainty to coordinate uncertainty. Note that
102 // the calculation is done in arcseconds, then converted to radians in
103 // order to achieve higher precision.
104 const static double scale = 1.0 / 3600.0;
105 const static Eigen::Matrix2d cdMatrix{{scale, 0}, {0, scale}};
106
107 lsst::geom::SpherePoint skyCenter = wcs.pixelToSky(center);
109 auto measurementToLocalGnomonic = wcs.getTransform()->then(*localGnomonicWcs->getTransform()->inverted());
110
111 Eigen::Matrix2d localMatrix = measurementToLocalGnomonic->getJacobian(center);
112 Eigen::Matrix2f d = localMatrix.cast<float>() * scale * (lsst::geom::PI / 180.0);
113
114 Eigen::Matrix2f skyCov = d * err * d.transpose();
115
116 // Multiply by declination correction matrix in order to get sigma(RA) * cos(Dec) for the uncertainty
117 // in RA, and cov(RA, Dec) * cos(Dec) for the RA/Dec covariance:
118 float cosDec = std::cos(skyCenter.getDec().asRadians());
119 Eigen::Matrix2f decCorr{{cosDec, 0}, {0, 1.0}};
120 Eigen::Matrix2f skyCovCorr = decCorr * skyCov * decCorr;
121 return skyCovCorr;
122}
123
124template <typename SourceCollection>
126 if (sourceList.empty()) {
127 return;
128 }
129 auto const schema = getSchema(sourceList[0]);
130 Point2DKey const centroidKey(schema["slot_Centroid"]);
131 CovarianceMatrixKey<float, 2> const centroidErrKey(schema["slot_Centroid"], {"x", "y"});
132 CoordKey const coordKey(schema["coord"]);
134 pixelList.reserve(sourceList.size());
136 skyErrList.reserve(sourceList.size());
137
138 for (auto const &source : sourceList) {
139 lsst::geom::Point2D center = getValue(source, centroidKey);
140 pixelList.emplace_back(center);
141 if (include_covariance) {
142 auto err = getValue(source, centroidErrKey);
143 Eigen::Matrix2f skyCov = calculateCoordCovariance(wcs, center, err);
144 skyErrList.emplace_back(skyCov);
145 }
146 }
147
149 auto skyCoord = skyList.cbegin();
150 auto skyErr = skyErrList.cbegin();
151 for (auto &source : sourceList) {
152 setValue(source, coordKey, *skyCoord);
153 if (include_covariance) {
155 setValue(source, coordErrKey, *skyErr);
156 }
157 ++skyCoord;
158 ++skyErr;
159 }
160}
161
164template void updateRefCentroids(geom::SkyWcs const &, SimpleCatalog &);
165
167 bool include_covariance);
168template void updateSourceCoords(geom::SkyWcs const &, SourceCatalog &, bool include_covariance);
170
171} // namespace table
172} // namespace afw
173} // namespace lsst
table::Key< table::Array< std::uint8_t > > wcs
Definition SkyWcs.cc:66
A 2-dimensional celestial WCS that transform pixels to ICRS RA/Dec, using the LSST standard for pixel...
Definition SkyWcs.h:117
Tag types used to declare specialized field types.
Definition misc.h:31
A FunctorKey used to get or set celestial coordinates from a pair of lsst::geom::Angle keys.
Definition aggregates.h:292
static ErrorKey getErrorKey(Schema const &schema)
T cos(T... args)
T get(T... args)
T isfinite(T... args)
std::shared_ptr< SkyWcs > makeSkyWcs(daf::base::PropertySet &metadata, bool strip=false)
Construct a SkyWcs from FITS keywords.
Definition SkyWcs.cc:521
void updateRefCentroids(geom::SkyWcs const &wcs, ReferenceCollection &refList)
Update centroids in a collection of reference objects.
Definition wcsUtils.cc:73
Eigen::Matrix2f calculateCoordCovariance(geom::SkyWcs const &wcs, lsst::geom::Point2D center, Eigen::Matrix2f err)
Calculate covariance for sky coordinates.
Definition wcsUtils.cc:95
void updateSourceCoords(geom::SkyWcs const &wcs, SourceCollection &sourceList, bool include_covariance=true)
Update sky coordinates in a collection of source objects.
Definition wcsUtils.cc:125
double constexpr PI
T Value
the type returned by BaseRecord::get
Definition FieldBase.h:42
table::Schema schema
Definition python.h:134