lsst.meas.astrom
14.0-7-g0d69b06+3
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Measure the distortions in an image plane and express them a SIP polynomials. More...
#include <CreateWcsWithSip.h>
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typedef std::shared_ptr< CreateWcsWithSip > | Ptr |
typedef std::shared_ptr< CreateWcsWithSip const > | ConstPtr |
Public Member Functions | |
CreateWcsWithSip (std::vector< MatchT > const &matches, afw::geom::SkyWcs const &linearWcs, int const order, afw::geom::Box2I const &bbox=afw::geom::Box2I(), int const ngrid=0) | |
Construct a CreateWcsWithSip. More... | |
std::shared_ptr< afw::geom::SkyWcs > | getNewWcs () |
double | getScatterInPixels () const |
Compute the median separation, in pixels, between items in this object's match list. More... | |
afw::geom::Angle | getScatterOnSky () const |
Compute the median on-sky separation between items in this object's match list. More... | |
double | getLinearScatterInPixels () const |
Compute the median radial separation between items in this object's match list. More... | |
afw::geom::Angle | getLinearScatterOnSky () const |
Compute the median on-sky separation between items in this object's match list,. More... | |
int | getOrder () const |
Return the number of terms in the SIP matrix. More... | |
int | getNPoints () const |
Return the number of points in the catalogue. More... | |
int | getNGrid () const |
Return the number of grid points (on each axis) used in inverse SIP transform. More... | |
Eigen::MatrixXd const | getSipA () |
Eigen::MatrixXd const | getSipB () |
Eigen::MatrixXd const | getSipAp () |
Eigen::MatrixXd const | getSipBp () |
Measure the distortions in an image plane and express them a SIP polynomials.
Given a list of matching sources between a catalogue and an image, and a linear Wcs that describes the mapping from pixel space in the image and ra/dec space in the catalogue, calculate discrepancies between the two and compute SIP distortion polynomials to describe the discrepancy
SIP polynomials are defined in Shupe at al. (2005) ASPC 347 491.
Note that the SIP standard insists (although it is only mentioned obliquly between Eqns 3 and 4) that the lowest three terms in the distortion polynomials be zero (A00, A10, A01, B00, etc.). To achieve this, we need to adjust the values of CD and CRPIX from the input wcs. This may not be the behaviour you expect.
A Wcs may be created in a variety of ways (e.g. lsst::meas::astrom::net::GlobalAstrometrySolution ), and the list of matched sources (matches) can be generated with the matchRaDec function.
Note that the matches must be one-to-one; this is ensured by passing closest=true to matchRaDec.
Definition at line 79 of file CreateWcsWithSip.h.
typedef std::shared_ptr<CreateWcsWithSip const> lsst::meas::astrom::sip::CreateWcsWithSip< MatchT >::ConstPtr |
Definition at line 83 of file CreateWcsWithSip.h.
typedef std::shared_ptr<CreateWcsWithSip> lsst::meas::astrom::sip::CreateWcsWithSip< MatchT >::Ptr |
Definition at line 82 of file CreateWcsWithSip.h.
lsst::meas::astrom::sip::CreateWcsWithSip< MatchT >::CreateWcsWithSip | ( | std::vector< MatchT > const & | matches, |
afw::geom::SkyWcs const & | linearWcs, | ||
int const | order, | ||
afw::geom::Box2I const & | bbox = afw::geom::Box2I() , |
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int const | ngrid = 0 |
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Construct a CreateWcsWithSip.
Constructor.
[in] | matches | list of matches |
[in] | linearWcs | initial WCS, typically pure TAN but need not be |
[in] | order | SIP order for fit WCS |
[in] | bbox | bounding box over which to compute the reverse SIP transform. If empty then a bounding box is computed based on the matches, extended a bit to allow for the fact that the sources will not necessarily reach to each edge of the image. Specifially the box is grown by dimensions/sqrt(number of matches). |
[in] | ngrid | number of points along x or y for the grid of points on which the reverse SIP transform is computed |
Definition at line 113 of file CreateWcsWithSip.cc.
double lsst::meas::astrom::sip::CreateWcsWithSip< MatchT >::getLinearScatterInPixels | ( | ) | const |
Compute the median radial separation between items in this object's match list.
For each match, project the reference object coord to pixels using the initial "linearWcs" WCS, and measure the radial separation to the source centroid.
Definition at line 381 of file CreateWcsWithSip.cc.
afwGeom::Angle lsst::meas::astrom::sip::CreateWcsWithSip< MatchT >::getLinearScatterOnSky | ( | ) | const |
Compute the median on-sky separation between items in this object's match list,.
For each match, project the source centroid to RA,Dec using the initial "linearWcs" WCS, and measure the on-sky angular separation to the reference source coord.
Definition at line 394 of file CreateWcsWithSip.cc.
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Definition at line 107 of file CreateWcsWithSip.h.
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Return the number of grid points (on each axis) used in inverse SIP transform.
Definition at line 146 of file CreateWcsWithSip.h.
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Return the number of points in the catalogue.
Definition at line 144 of file CreateWcsWithSip.h.
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Return the number of terms in the SIP matrix.
Definition at line 142 of file CreateWcsWithSip.h.
double lsst::meas::astrom::sip::CreateWcsWithSip< MatchT >::getScatterInPixels | ( | ) | const |
Compute the median separation, in pixels, between items in this object's match list.
For each match, project the reference object coord to pixels using the fit TAN-SIP WCS, and measure the radial separation to the source centroid
Definition at line 375 of file CreateWcsWithSip.cc.
afwGeom::Angle lsst::meas::astrom::sip::CreateWcsWithSip< MatchT >::getScatterOnSky | ( | ) | const |
Compute the median on-sky separation between items in this object's match list.
For each match, project the source centroid to RA,Dec using the fit TAN-SIP WCS, and measure the on-sky angular separation to the reference source coord.
Definition at line 387 of file CreateWcsWithSip.cc.
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Definition at line 149 of file CreateWcsWithSip.h.
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Definition at line 153 of file CreateWcsWithSip.h.
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Definition at line 151 of file CreateWcsWithSip.h.
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Definition at line 155 of file CreateWcsWithSip.h.