def testReadLsstSkyWcsStripMetadata(self):
metadata = self.makeMetadata()
self.assertEqual(len(metadata.toList()), 32)
readLsstSkyWcs(metadata, strip=False)
self.assertEqual(len(metadata.toList()), 32)
readLsstSkyWcs(metadata, strip=True)
self.assertEqual(len(metadata.toList()), 18)
def testReadLsstSkyWcsNormalizeFk5(self):
"""Test that readLsstSkyWcs correctly normalizes FK5 1975 to ICRS
"""
equinox = 1975
metadata = self.makeMetadata()
metadata.set("RADESYS", "FK5")
metadata.set("EQUINOX", equinox)
crpix = self.getCrpix(metadata)
# record the original CRVAL before reading and stripping metadata
crvalFk5Deg = (metadata.get("CRVAL1"), metadata.get("CRVAL2"))
# read frameSet and compute crval
frameSet = readLsstSkyWcs(metadata, strip=True)
crvalRadians = frameSet.applyForward(crpix)
crvalPoint = SpherePoint(*[crvalRadians[i]*radians for i in range(2)])
# compare crval to the value recorded as the skyRef property of the current frame
skyFrame = frameSet.getFrame(ast.FrameSet.CURRENT)
recordedCrvalRadians = skyFrame.getSkyRef()
recordedCrvalPoint = SpherePoint(*[recordedCrvalRadians[i]*radians for i in range(2)])
self.assertSpherePointsAlmostEqual(crvalPoint, recordedCrvalPoint)
# get predicted crval by converting with astropy
crvalFk5 = SkyCoord(crvalFk5Deg[0], crvalFk5Deg[1], frame="fk5",
equinox="J%f" % (equinox,), unit="deg")
predictedCrvalIcrs = crvalFk5.icrs
predictedCrvalPoint = SpherePoint(predictedCrvalIcrs.ra.radian*radians,
predictedCrvalIcrs.dec.radian*radians)
# AST and astropy disagree by 0.025 arcsec; it's not worth worrying about because
# we will always use ICRS internally and almost always fit our own WCS.
self.assertSpherePointsAlmostEqual(crvalPoint, predictedCrvalPoint, maxSep=0.05*arcseconds)
def testReadLsstSkyWcsNormalizeFk5(self):
"""Test that readLsstSkyWcs correctly normalizes FK5 1975 to ICRS
"""
equinox = 1975
metadata = self.makeMetadata()
metadata.set("RADESYS", "FK5")
metadata.set("EQUINOX", equinox)
crpix = self.getCrpix(metadata)
# record the original CRVAL before reading and stripping metadata
crvalFk5Deg = (metadata.getScalar("CRVAL1"), metadata.getScalar("CRVAL2"))
# read frameSet and compute crval
frameSet = readLsstSkyWcs(metadata, strip=True)
crvalRadians = frameSet.applyForward(crpix)
crvalPoint = SpherePoint(*[crvalRadians[i]*radians for i in range(2)])
# compare crval to the value recorded as the skyRef property of the current frame
skyFrame = frameSet.getFrame(ast.FrameSet.CURRENT)
recordedCrvalRadians = skyFrame.getSkyRef()
recordedCrvalPoint = SpherePoint(*[recordedCrvalRadians[i]*radians for i in range(2)])
self.assertSpherePointsAlmostEqual(crvalPoint, recordedCrvalPoint)
# get predicted crval by converting with astropy
crvalFk5 = SkyCoord(crvalFk5Deg[0], crvalFk5Deg[1], frame="fk5",
equinox="J%f" % (equinox,), unit="deg")
predictedCrvalIcrs = crvalFk5.icrs
predictedCrvalPoint = SpherePoint(predictedCrvalIcrs.ra.radian*radians,
predictedCrvalIcrs.dec.radian*radians)
# AST and astropy disagree by 0.025 arcsec; it's not worth worrying about because
# we will always use ICRS internally and almost always fit our own WCS.
self.assertSpherePointsAlmostEqual(crvalPoint, predictedCrvalPoint, maxSep=0.05*arcseconds)
def testReadLsstSkyWcsStripMetadata(self):
metadata = self.makeMetadata()
nKeys = len(metadata.toList())
nToStrip = 12 + 6 # WCS "A" is also stripped
frameSet1 = readLsstSkyWcs(metadata, strip=False)
self.assertEqual(len(metadata.toList()), nKeys)
crval = SpherePoint(metadata.get("CRVAL1")*degrees, metadata.get("CRVAL2")*degrees)
crvalRad = crval.getPosition(radians)
desiredCrpix = self.getCrpix(metadata)
computedCrpix = frameSet1.applyInverse(crvalRad)
self.assertPairsAlmostEqual(desiredCrpix, computedCrpix)
# read again, this time stripping metadata
frameSet2 = readLsstSkyWcs(metadata, strip=True)
self.assertEqual(len(metadata.toList()), nKeys - nToStrip)
self.assertEqual(frameSet1, frameSet2)
# having stripped the WCS keywords, we should not be able to generate
# a WCS from what's left
with self.assertRaises(lsst.pex.exceptions.TypeError):
readLsstSkyWcs(metadata, strip=False)
# try a full WCS with just CRPIX1 or 2 missing
for i in (1, 2):
metadata = self.makeMetadata()
metadata.remove("CRPIX%d" % (i,))
with self.assertRaises(lsst.pex.exceptions.TypeError):
readLsstSkyWcs(metadata, strip=False)
def testReadLsstSkyWcsStripMetadata(self):
metadata = self.makeMetadata()
nKeys = len(metadata.toList())
nToStrip = 12 + 6 # WCS "A" is also stripped
frameSet1 = readLsstSkyWcs(metadata, strip=False)
self.assertEqual(len(metadata.toList()), nKeys)
crval = SpherePoint(metadata.getScalar("CRVAL1"), metadata.getScalar("CRVAL2"), degrees)
crvalRad = crval.getPosition(radians)
desiredCrpix = self.getCrpix(metadata)
computedCrpix = frameSet1.applyInverse(crvalRad)
self.assertPairsAlmostEqual(desiredCrpix, computedCrpix)
# read again, this time stripping metadata
frameSet2 = readLsstSkyWcs(metadata, strip=True)
self.assertEqual(len(metadata.toList()), nKeys - nToStrip)
self.assertEqual(frameSet1, frameSet2)
# having stripped the WCS keywords, we should not be able to generate
# a WCS from what's left
with self.assertRaises(lsst.pex.exceptions.TypeError):
readLsstSkyWcs(metadata, strip=False)
# try a full WCS with just CRPIX1 or 2 missing
for i in (1, 2):
metadata = self.makeMetadata()
metadata.remove("CRPIX%d" % (i,))
with self.assertRaises(lsst.pex.exceptions.TypeError):
readLsstSkyWcs(metadata, strip=False)
def testReadLsstSkyWcsNormalizeRaDec(self):
"""Test that a Dec, RA WCS frame set is normalized to RA, Dec
"""
metadata = self.makeMetadata()
crpix = self.getCrpix(metadata)
# swap RA, Decaxes in metadata
crvalIn = SpherePoint(metadata.get("CRVAL1")*degrees, metadata.get("CRVAL2")*degrees)
metadata.set("CRVAL1", crvalIn[1].asDegrees())
metadata.set("CRVAL2", crvalIn[0].asDegrees())
metadata.set("CTYPE1", "DEC--TAN")
metadata.set("CTYPE2", "RA---TAN")
# create the wcs
frameSet = readLsstSkyWcs(metadata)
# compute pixel origin and compare to input crval
computedCrvalRadians = frameSet.applyForward(crpix)
computedCrval = SpherePoint(*[computedCrvalRadians[i]*radians for i in range(2)])
self.assertSpherePointsAlmostEqual(crvalIn, computedCrval)
def testReadLsstSkyWcsNormalizeRaDec(self):
"""Test that a Dec, RA WCS frame set is normalized to RA, Dec
"""
metadata = self.makeMetadata()
crpix = self.getCrpix(metadata)
# swap RA, Decaxes in metadata
crvalIn = SpherePoint(metadata.getScalar("CRVAL1"), metadata.getScalar("CRVAL2"), degrees)
metadata.set("CRVAL1", crvalIn[1].asDegrees())
metadata.set("CRVAL2", crvalIn[0].asDegrees())
metadata.set("CTYPE1", "DEC--TAN")
metadata.set("CTYPE2", "RA---TAN")
# create the wcs
frameSet = readLsstSkyWcs(metadata)
# compute pixel origin and compare to input crval
computedCrvalRadians = frameSet.applyForward(crpix)
computedCrval = SpherePoint(*[computedCrvalRadians[i]*radians for i in range(2)])
self.assertSpherePointsAlmostEqual(crvalIn, computedCrval)
