def test_FitsChanFitsTol(self):
"""Test that increasing FitsTol allows writing a WCS with distortion
as FITS-WCS.
"""
ss = ast.StringStream("".join(self.cards))
fc = ast.FitsChan(ss, "Encoding=FITS-WCS, IWC=1")
frameSet = fc.read()
distortion = ast.PcdMap(0.001, [0.0, 0.0])
distortedFrameSet = self.insertPixelMapping(distortion, frameSet)
# Writing as FTIS-WCS should fail with the default FitsTol
fc = writeFitsWcs(distortedFrameSet)
self.assertEqual(fc.nCard, 0)
# Writing as FITS-WCS should succeed with adequate FitsTol
fc2 = writeFitsWcs(distortedFrameSet, "FitsTol=1000")
self.assertGreater(fc2.nCard, 9)
for i in (1, 2):
fv = fc2.getFitsF("CRVAL%d" % (i,))
self.assertAlmostEqual(fv.value, 0)
fv2 = fc2.getFitsS("CTYPE1")
self.assertEqual(fv2.value, "RA---TAN")
fv3 = fc2.getFitsS("CTYPE2")
self.assertEqual(fv3.value, "DEC--TAN")
def test_PcdMap(self):
coeff = 0.002
ctr = [2, 3]
pcdmap = ast.PcdMap(coeff, ctr)
self.assertEqual(pcdmap.className, "PcdMap")
self.assertIsInstance(pcdmap, ast.PcdMap)
self.assertIsInstance(pcdmap, ast.Mapping)
self.assertEqual(pcdmap.nIn, 2)
self.assertEqual(pcdmap.nOut, 2)
self.assertEqual(pcdmap.disco, coeff)
assert_allclose(pcdmap.pcdCen, ctr)
self.checkBasicSimplify(pcdmap)
self.checkCopy(pcdmap)
# the center maps to itself
assert_allclose(pcdmap.applyForward(ctr), ctr)
indata = np.array([
[0.0, -1.0, 4.2],
[0.0, 7.3, -5.3],
])
# inverse uses a fit so don't expect too much
self.checkRoundTrip(pcdmap, indata, atol=1e-4)
self.checkMappingPersistence(pcdmap, indata)
outdata = pcdmap.applyForward(indata)
# the mapping is:
# outrad = inrad*(1 + coeff*inrad^2)
# outdir = indir
# where radius and direction are relative to the center of distortion
inrelctr = (indata.T - ctr).T
inrelctrrad = np.hypot(inrelctr[0], inrelctr[1])
inrelctrdir = np.arctan2(inrelctr[1], inrelctr[0])
pred_outrad = inrelctrrad * (1 + coeff * inrelctrrad * inrelctrrad)
pred_outrelctr = np.zeros(indata.shape, dtype=float)
pred_outrelctr[0, :] = pred_outrad * np.cos(inrelctrdir)
pred_outrelctr[1, :] = pred_outrad * np.sin(inrelctrdir)
pred_outdata = pred_outrelctr + np.expand_dims(ctr, 1)
assert_allclose(outdata, pred_outdata)
def test_PcdMapBadConstruction(self):
with self.assertRaises(Exception):
ast.PcdMap(0.5, [1, 2, 3])
with self.assertRaises(Exception):
ast.PcdMap(0.5, [1])