def __init__(self, wcs, wcsinfo):
"""
Parameters
----------
wcs : GWCS
A `GWCS` object.
wcsinfo : dict
A dictionary containing reference angles of ``JWST`` instrument
provided in the ``wcsinfo`` property of ``JWST`` meta data.
This dictionary **must contain** the following keys and values:
'v2_ref' : float
V2 position of the reference point in arc seconds.
'v3_ref' : float
V3 position of the reference point in arc seconds.
'roll_ref' : float
Roll angle in degrees.
"""
if TPCorr is None:
raise ImportError("The 'jwst' package must be installed in order "
"to correct JWST WCS.")
valid, message = self._check_wcs_structure(wcs)
if not valid:
raise ValueError("Unsupported WCS structure: {}".format(message))
v2_ref = wcsinfo['v2_ref']
v3_ref = wcsinfo['v3_ref']
roll_ref = wcsinfo['roll_ref']
self._wcsinfo = {'v2_ref': v2_ref, 'v3_ref': v3_ref,
'roll_ref': roll_ref}
# perform additional check that if tangent plane correction is already
# present in the WCS pipeline, it is of TPCorr class and that
# its parameters are consistent with reference angles:
frms = wcs.available_frames
if 'v2v3corr' in frms:
self._v23name = 'v2v3corr'
self._tpcorr = deepcopy(
wcs.pipeline[frms.index('v2v3corr') - 1][1]
)
self._default_tpcorr = None
if not isinstance(self._tpcorr, TPCorr):
raise ValueError("Unsupported tangent-plance correction type.")
# check that transformation parameters are consistent with
# reference angles:
v2ref = self._tpcorr.v2ref.value
v3ref = self._tpcorr.v3ref.value
roll = self._tpcorr.roll.value
eps_v2 = 10.0 * np.finfo(v2_ref).eps
eps_v3 = 10.0 * np.finfo(v3_ref).eps
eps_roll = 10.0 * np.finfo(roll_ref).eps
if not (np.isclose(v2_ref, v2ref * 3600.0, rtol=eps_v2) and
np.isclose(v3_ref, v3ref * 3600.0, rtol=eps_v3) and
np.isclose(roll_ref, roll, rtol=eps_roll)):
raise ValueError(
"WCS/TPCorr parameters 'v2ref', 'v3ref', and/or 'roll' "
"differ from the corresponding reference values."
)
else:
self._v23name = 'v2v3'
self._tpcorr = None
self._default_tpcorr = TPCorr(
v2ref=v2_ref / 3600.0, v3ref=v3_ref / 3600.0, roll=roll_ref,
name='tangent-plane linear correction'
)
super().__init__(wcs)
self._update_transformations()
def set_correction(self, matrix=[[1, 0], [0, 1]], shift=[0, 0], meta=None,
**kwargs):
"""
Sets a tangent-plane correction of the GWCS object according to
the provided liniar parameters. In addition, this function updates
the ``meta`` attribute of the `JWSTgWCS` object with the values
of keyword arguments except for the argument ``meta`` which is
*merged* with the *attribute* ``meta``.
Parameters
----------
matrix : list, numpy.ndarray
A ``2x2`` array or list of lists coefficients representing scale,
rotation, and/or skew transformations.
shift : list, numpy.ndarray
A list of two coordinate shifts to be applied to coordinates
*before* ``matrix`` transformations are applied.
meta : dict, None, optional
Dictionary that will be merged to the object's ``meta`` fields.
**kwargs : optional parameters
Optional parameters for the WCS corrector. `JWSTgWCS` ignores these
arguments (except for storing them in the ``meta`` attribute).
"""
frms = self._wcs.available_frames
# if original WCS did not have tangent-plane corrections, create
# new correction and add it to the WCs pipeline:
if self._tpcorr is None:
self._tpcorr = TPCorr(
v2ref=self._wcsinfo['v2_ref'] / 3600.0,
v3ref=self._wcsinfo['v3_ref'] / 3600.0,
roll=self._wcsinfo['roll_ref'],
matrix=matrix,
shift=shift,
name='tangent-plane linear correction'
)
idx_v2v3 = frms.index(self._v23name)
pipeline = deepcopy(self._wcs.pipeline)
pf, pt = pipeline[idx_v2v3]
pipeline[idx_v2v3] = (pf, deepcopy(self._tpcorr))
frm_v2v3corr = deepcopy(pf)
frm_v2v3corr.name = 'v2v3corr'
pipeline.insert(idx_v2v3 + 1, (frm_v2v3corr, pt))
self._wcs = gwcs.WCS(pipeline, name=self._owcs.name)
self._v23name = 'v2v3corr'
else:
# combine old and new corrections into a single one and replace
# old transformation with the combined correction transformation:
tpcorr2 = self._tpcorr.__class__(
v2ref=self._tpcorr.v2ref, v3ref=self._tpcorr.v3ref,
roll=self._tpcorr.roll, matrix=matrix, shift=shift,
name='tangent-plane linear correction'
)
self._tpcorr = tpcorr2.combine(tpcorr2, self._tpcorr)
idx_v2v3 = frms.index(self._v23name)
pipeline = deepcopy(self._wcs.pipeline)
pipeline[idx_v2v3 - 1] = (pipeline[idx_v2v3 - 1][0],
deepcopy(self._tpcorr))
self._wcs = gwcs.WCS(pipeline, name=self._owcs.name)
# reset definitions of the transformations from detector/world
# coordinates to the tangent plane:
self._update_transformations()
# save linear transformation info to the meta attribute:
self._meta['matrix'] = matrix
self._meta['shift'] = shift
if meta is not None:
self._meta.update(meta)
class JWSTgWCS(TPWCS):
""" A class for holding ``JWST`` ``gWCS`` information and for managing
tangent-plane corrections.
"""
def __init__(self, wcs, wcsinfo):
"""
Parameters
----------
wcs : GWCS
A `GWCS` object.
wcsinfo : dict
A dictionary containing reference angles of ``JWST`` instrument
provided in the ``wcsinfo`` property of ``JWST`` meta data.
This dictionary **must contain** the following keys and values:
'v2_ref' : float
V2 position of the reference point in arc seconds.
'v3_ref' : float
V3 position of the reference point in arc seconds.
'roll_ref' : float
Roll angle in degrees.
"""
if TPCorr is None:
raise ImportError("The 'jwst' package must be installed in order "
"to correct JWST WCS.")
valid, message = self._check_wcs_structure(wcs)
if not valid:
raise ValueError("Unsupported WCS structure: {}".format(message))
v2_ref = wcsinfo['v2_ref']
v3_ref = wcsinfo['v3_ref']
roll_ref = wcsinfo['roll_ref']
self._wcsinfo = {'v2_ref': v2_ref, 'v3_ref': v3_ref,
'roll_ref': roll_ref}
# perform additional check that if tangent plane correction is already
# present in the WCS pipeline, it is of TPCorr class and that
# its parameters are consistent with reference angles:
frms = wcs.available_frames
if 'v2v3corr' in frms:
self._v23name = 'v2v3corr'
self._tpcorr = deepcopy(
wcs.pipeline[frms.index('v2v3corr') - 1][1]
)
self._default_tpcorr = None
if not isinstance(self._tpcorr, TPCorr):
raise ValueError("Unsupported tangent-plance correction type.")
# check that transformation parameters are consistent with
# reference angles:
v2ref = self._tpcorr.v2ref.value
v3ref = self._tpcorr.v3ref.value
roll = self._tpcorr.roll.value
eps_v2 = 10.0 * np.finfo(v2_ref).eps
eps_v3 = 10.0 * np.finfo(v3_ref).eps
eps_roll = 10.0 * np.finfo(roll_ref).eps
if not (np.isclose(v2_ref, v2ref * 3600.0, rtol=eps_v2) and
np.isclose(v3_ref, v3ref * 3600.0, rtol=eps_v3) and
np.isclose(roll_ref, roll, rtol=eps_roll)):
raise ValueError(
"WCS/TPCorr parameters 'v2ref', 'v3ref', and/or 'roll' "
"differ from the corresponding reference values."
)
else:
self._v23name = 'v2v3'
self._tpcorr = None
self._default_tpcorr = TPCorr(
v2ref=v2_ref / 3600.0, v3ref=v3_ref / 3600.0, roll=roll_ref,
name='tangent-plane linear correction'
)
super().__init__(wcs)
self._update_transformations()
def _update_transformations(self):
# define transformations from detector/world coordinates to
# the tangent plane:
detname = self._wcs.pipeline[0][0].name
worldname = self._wcs.pipeline[-1][0].name
self._world_to_v23 = self._wcs.get_transform(worldname, self._v23name)
self._v23_to_world = self._wcs.get_transform(self._v23name, worldname)
self._det_to_v23 = self._wcs.get_transform(detname, self._v23name)
self._v23_to_det = self._wcs.get_transform(self._v23name, detname)
self._det_to_world = self._wcs.__call__
self._world_to_det = self._wcs.invert
@property
def ref_angles(self):
""" Return a ``wcsinfo``-like dictionary of main WCS parameters. """
return {k: v for k, v in self._wcsinfo.items()}
def set_correction(self, matrix=[[1, 0], [0, 1]], shift=[0, 0], meta=None,
**kwargs):
"""
Sets a tangent-plane correction of the GWCS object according to
the provided liniar parameters. In addition, this function updates
the ``meta`` attribute of the `JWSTgWCS` object with the values
of keyword arguments except for the argument ``meta`` which is
*merged* with the *attribute* ``meta``.
Parameters
----------
matrix : list, numpy.ndarray
A ``2x2`` array or list of lists coefficients representing scale,
rotation, and/or skew transformations.
shift : list, numpy.ndarray
A list of two coordinate shifts to be applied to coordinates
*before* ``matrix`` transformations are applied.
meta : dict, None, optional
Dictionary that will be merged to the object's ``meta`` fields.
**kwargs : optional parameters
Optional parameters for the WCS corrector. `JWSTgWCS` ignores these
arguments (except for storing them in the ``meta`` attribute).
"""
frms = self._wcs.available_frames
# if original WCS did not have tangent-plane corrections, create
# new correction and add it to the WCs pipeline:
if self._tpcorr is None:
self._tpcorr = TPCorr(
v2ref=self._wcsinfo['v2_ref'] / 3600.0,
v3ref=self._wcsinfo['v3_ref'] / 3600.0,
roll=self._wcsinfo['roll_ref'],
matrix=matrix,
shift=shift,
name='tangent-plane linear correction'
)
idx_v2v3 = frms.index(self._v23name)
pipeline = deepcopy(self._wcs.pipeline)
pf, pt = pipeline[idx_v2v3]
pipeline[idx_v2v3] = (pf, deepcopy(self._tpcorr))
frm_v2v3corr = deepcopy(pf)
frm_v2v3corr.name = 'v2v3corr'
pipeline.insert(idx_v2v3 + 1, (frm_v2v3corr, pt))
self._wcs = gwcs.WCS(pipeline, name=self._owcs.name)
self._v23name = 'v2v3corr'
else:
# combine old and new corrections into a single one and replace
# old transformation with the combined correction transformation:
tpcorr2 = self._tpcorr.__class__(
v2ref=self._tpcorr.v2ref, v3ref=self._tpcorr.v3ref,
roll=self._tpcorr.roll, matrix=matrix, shift=shift,
name='tangent-plane linear correction'
)
self._tpcorr = tpcorr2.combine(tpcorr2, self._tpcorr)
idx_v2v3 = frms.index(self._v23name)
pipeline = deepcopy(self._wcs.pipeline)
pipeline[idx_v2v3 - 1] = (pipeline[idx_v2v3 - 1][0],
deepcopy(self._tpcorr))
self._wcs = gwcs.WCS(pipeline, name=self._owcs.name)
# reset definitions of the transformations from detector/world
# coordinates to the tangent plane:
self._update_transformations()
# save linear transformation info to the meta attribute:
self._meta['matrix'] = matrix
self._meta['shift'] = shift
if meta is not None:
self._meta.update(meta)
def _check_wcs_structure(self, wcs):
if wcs is None or wcs.pipeline is None:
return False, "Either WCS or its pipeline is None."
frms = wcs.available_frames
nframes = len(frms)
if nframes < 3:
return False, "There are fewer than 3 frames in the WCS pipeline."
if frms.count(frms[0]) > 1 or frms.count(frms[-1]) > 1:
return (False, "First and last frames in the WCS pipeline must "
"be unique.")
if frms.count('v2v3') != 1:
return (False, "Only one 'v2v3' frame is allowed in the WCS "
"pipeline.")
idx_v2v3 = frms.index('v2v3')
if idx_v2v3 == 0 or idx_v2v3 == (nframes - 1):
return (False, "'v2v3' frame cannot be first or last in the WCS "
"pipeline.")
nv2v3corr = frms.count('v2v3corr')
if nv2v3corr == 0:
return True, ''
elif nv2v3corr > 1:
return (False, "Only one 'v2v3corr' correction frame is allowed "
"in the WCS pipeline.")
idx_v2v3corr = frms.index('v2v3corr')
if idx_v2v3corr != (idx_v2v3 + 1) or idx_v2v3corr == (nframes - 1):
return (False, "'v2v3corr' frame is not in the correct position "
"in the WCS pipeline.")
return True, ''
def det_to_world(self, x, y):
"""
Convert pixel coordinates to sky coordinates using full
(i.e., including distortions) transformations.
"""
ra, dec = self._det_to_world(x, y)
return ra, dec
def world_to_det(self, ra, dec):
"""
Convert sky coordinates to image's pixel coordinates using full
(i.e., including distortions) transformations.
"""
x, y = self._world_to_det(ra, dec)
return x, y
def det_to_tanp(self, x, y):
"""
Convert detector (pixel) coordinates to tangent plane coordinates.
"""
tpc = self._default_tpcorr if self._tpcorr is None else self._tpcorr
v2, v3 = self._det_to_v23(x, y)
x, y = tpc.v2v3_to_tanp(v2, v3)
return x, y
def tanp_to_det(self, x, y):
"""
Convert tangent plane coordinates to detector (pixel) coordinates.
"""
tpc = self._default_tpcorr if self._tpcorr is None else self._tpcorr
v2, v3 = tpc.tanp_to_v2v3(x, y)
x, y = self._v23_to_det(v2, v3)
return x, y
def world_to_tanp(self, ra, dec):
"""
Convert tangent plane coordinates to detector (pixel) coordinates.
"""
tpc = self._default_tpcorr if self._tpcorr is None else self._tpcorr
v2, v3 = self._world_to_v23(ra, dec)
x, y = tpc.v2v3_to_tanp(v2, v3)
return x, y
def tanp_to_world(self, x, y):
"""
Convert tangent plane coordinates to world coordinates.
"""
tpc = self._default_tpcorr if self._tpcorr is None else self._tpcorr
v2, v3 = tpc.tanp_to_v2v3(x, y)
ra, dec = self._v23_to_world(v2, v3)
return ra, dec