def testConstruction(self):
poly = makeRandomPolynomialTransform(4, sip=True)
cd = lsst.afw.geom.LinearTransform(np.random.randn(2, 2))
crpix = lsst.afw.geom.Point2D(*np.random.randn(2))
sip = SipForwardTransform(crpix, cd, poly)
self.assertTransformsAlmostEqual(
sip, lambda p: cd(
(p - crpix) + poly(lsst.afw.geom.Point2D(p - crpix))))
def testMakeWcs(self):
fwd = self.makeRandom()
rev = SipReverseTransform( # this isn't actually the inverse of fwd, but that doesn't matter
fwd.getPixelOrigin(), fwd.getCDMatrix(),
makeRandomPolynomialTransform(4))
crval = lsst.afw.geom.Point2D(45.0, 45.0)
wcs = lsst.meas.astrom.makeWcs(
fwd, rev, lsst.afw.coord.IcrsCoord(crval, lsst.afw.geom.degrees))
self.assertFloatsAlmostEqual(fwd.getPoly().getXCoeffs(), wcs.getSipA())
self.assertFloatsAlmostEqual(fwd.getPoly().getYCoeffs(), wcs.getSipB())
self.assertFloatsAlmostEqual(rev.getPoly().getXCoeffs(),
wcs.getSipAp())
self.assertFloatsAlmostEqual(rev.getPoly().getYCoeffs(),
wcs.getSipBp())
# We can only test agreement with TanWcs in one direction, because
# TanWcs doesn't provide an inverse to skyToIntermediateWorldCoord.
def t1(p):
sky = lsst.afw.coord.IcrsCoord(crval + lsst.afw.geom.Extent2D(p),
lsst.afw.geom.degrees)
return rev(wcs.skyToIntermediateWorldCoord(sky))
def t2(p):
sky = lsst.afw.coord.IcrsCoord(crval + lsst.afw.geom.Extent2D(p),
lsst.afw.geom.degrees)
return wcs.skyToPixel(sky)
self.assertTransformsAlmostEqual(t1, t2)
fwd2 = SipForwardTransform.extract(wcs)
rev2 = SipReverseTransform.extract(wcs)
self.assertPairsAlmostEqual(fwd.getPixelOrigin(),
fwd2.getPixelOrigin())
self.assertPairsAlmostEqual(rev.getPixelOrigin(),
rev2.getPixelOrigin())
self.assertFloatsAlmostEqual(fwd.getCDMatrix().getMatrix(),
fwd2.getCDMatrix().getMatrix())
self.assertFloatsAlmostEqual(rev.getCDMatrix().getMatrix(),
rev2.getCDMatrix().getMatrix())
self.assertFloatsAlmostEqual(fwd.getPoly().getXCoeffs(),
fwd2.getPoly().getXCoeffs())
self.assertFloatsAlmostEqual(fwd.getPoly().getYCoeffs(),
fwd2.getPoly().getYCoeffs())
self.assertFloatsAlmostEqual(rev.getPoly().getXCoeffs(),
rev2.getPoly().getXCoeffs())
self.assertFloatsAlmostEqual(rev.getPoly().getYCoeffs(),
rev2.getPoly().getYCoeffs())
def makeRandomSipForwardTransform(order):
return SipForwardTransform(
lsst.afw.geom.Point2D(*np.random.randn(2)),
lsst.afw.geom.LinearTransform(np.random.randn(2, 2)),
makeRandomPolynomialTransform(order, sip=True))
def testMakeWcs(self):
"""Test SipForwardTransform, SipReverseTransform and makeWcs
"""
filename = os.path.join(os.path.dirname(__file__),
'imgCharSources-v85501867-R01-S00.sipheader')
sipMetadata = readMetadata(filename)
# We're building an ICRS-based TAN-SIP using coefficients read from metadata
# so ignore the RADESYS in metadata (which is missing anyway, falling back to FK5)
sipMetadata.set("RADESYS", "ICRS")
crpix = lsst.afw.geom.Point2D(
sipMetadata.get("CRPIX1") - 1,
sipMetadata.get("CRPIX2") - 1,
)
crval = lsst.afw.geom.SpherePoint(
sipMetadata.get("CRVAL1"),
sipMetadata.get("CRVAL2"),
lsst.afw.geom.degrees,
)
cdLinearTransform = lsst.afw.geom.LinearTransform(
getCdMatrixFromMetadata(sipMetadata))
aArr = getSipMatrixFromMetadata(sipMetadata, "A")
bArr = getSipMatrixFromMetadata(sipMetadata, "B")
apArr = getSipMatrixFromMetadata(sipMetadata, "AP")
bpArr = getSipMatrixFromMetadata(sipMetadata, "BP")
abPoly = PolynomialTransform(aArr, bArr)
abRevPoly = PolynomialTransform(apArr, bpArr)
fwd = SipForwardTransform(crpix, cdLinearTransform, abPoly)
rev = SipReverseTransform(crpix, cdLinearTransform, abRevPoly)
wcsFromMakeWcs = lsst.meas.astrom.makeWcs(fwd, rev, crval)
wcsFromMetadata = lsst.afw.geom.makeSkyWcs(sipMetadata, strip=False)
# Check SipForwardTransform against a local implementation
localPixelToIwc = makeSipPixelToIwc(sipMetadata)
self.assertTransformsAlmostEqual(fwd,
localPixelToIwc.applyForward,
maxval=2000)
# Compare SipReverseTransform against a local implementation
# Use the forward direction first to get sensible inputs
localIwcToPixel = makeSipIwcToPixel(sipMetadata)
def fwdThenRev(p):
return rev(fwd(p))
def fwdThenLocalRev(p):
return localIwcToPixel.applyForward(fwd(p))
self.assertTransformsAlmostEqual(fwdThenRev,
fwdThenLocalRev,
maxval=2000)
# Check that SipReverseTransform is the inverse of SipForwardTransform;
# this is not perfect because the coefficients don't define a perfect inverse
def nullTransform(p):
return p
self.assertTransformsAlmostEqual(fwdThenRev,
nullTransform,
maxval=2000,
atol=1e-3)
# Check SipForwardTransform against the one contained in wcsFromMakeWcs
# (Don't bother with the other direction because the WCS transform is iterative,
# so it doesn't tell us anything useful about SipReverseTransform
pixelToIwc = lsst.afw.geom.getPixelToIntermediateWorldCoords(
wcsFromMetadata)
self.assertTransformsAlmostEqual(fwd,
pixelToIwc.applyForward,
maxval=2000)
# Check a WCS constructed from SipForwardTransform, SipReverseTransform
# against one constructed directly from the metadata
bbox = lsst.afw.geom.Box2D(lsst.afw.geom.Point2D(0, 0),
lsst.afw.geom.Extent2D(2000, 2000))
self.assertWcsAlmostEqualOverBBox(wcsFromMakeWcs, wcsFromMetadata,
bbox)