The print(wcs.tofits_sip()) failed in your example in https://gwcs.readthedocs.io/en/latest/#a-step-by-step-example-of-constructing-an-imaging-gwcs-object

[lznakano]

I followed the example in https://gwcs.readthedocs.io/en/latest/#a-step-by-step-example-of-constructing-an-imaging-gwcs-object to make a wcs. When I tried to print it out, it failed with a lot of errors.
Here is the function I defined (copied and pasted from the example):

from astropy.io import fits
import astropy.time as time
import os
from astropy.modeling import models
import asdf
from astropy import units as u
import astropy.time as atime
import roman_datamodels.datamodels as rdm
import roman_datamodels.stnode as stnode
import numpy as np
from astropy import coordinates as coord
from gwcs import wcs
from gwcs import coordinate_frames as cf
from gwcs.utils import make_fitswcs_transform
from roman_datamodels import units as ru

#compose a wcs object
def make_wcs():
   shift_by_crpix = models.Shift(-(2048 - 1)*u.pix) & models.Shift(-(1024 - 1)*u.pix)
   matrix = np.array([[1.290551569736E-05, 5.9525007864732E-06],
                   [5.0226382102765E-06 , -1.2644844123757E-05]])
   rotation = models.AffineTransformation2D(matrix * u.deg,
                                         translation=[0, 0] * u.deg)
   rotation.input_units_equivalencies = {"x": u.pixel_scale(1*u.deg/u.pix),
                                      "y": u.pixel_scale(1*u.deg/u.pix)}
   rotation.inverse = models.AffineTransformation2D(np.linalg.inv(matrix) * u.pix,
                                                 translation=[0, 0] * u.pix)
   rotation.inverse.input_units_equivalencies = {"x": u.pixel_scale(1*u.pix/u.deg),
                                              "y": u.pixel_scale(1*u.pix/u.deg)}

   tan = models.Pix2Sky_TAN()
   celestial_rotation =  models.RotateNative2Celestial(5.63056810618*u.deg, -72.05457184279*u.deg, 180*u.deg)
   det2sky = shift_by_crpix | rotation | tan | celestial_rotation
   det2sky.name = "linear_transform"


   detector_frame = cf.Frame2D(name="detector", axes_names=("x", "y"),
                            unit=(u.pix, u.pix))
   sky_frame = cf.CelestialFrame(reference_frame=coord.ICRS(), name='icrs',
                              unit=(u.deg, u.deg))

   pipeline = [(detector_frame, det2sky),
            (sky_frame, None)
           ]
   wcsobj = wcs.WCS(pipeline)
   wcsobj.bounding_box = ((0, 2048), (0,1024))
   return wcsobj`

wcs=make_wcs()
print(wcs.to_fits_sip())

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/gwcs/wcs.py:1609, in WCS.to_fits_sip(self, bounding_box, max_pix_error, degree, max_inv_pix_error, inv_degree, npoints, crpix, projection, verbose)
1606 if celestial_group is None:
1607 raise ValueError("The to_fits_sip requires an output celestial frame.")
-> 1609 hdr = self._to_fits_sip(
1610 celestial_group=celestial_group,
1611 keep_axis_position=False,
1612 bounding_box=bounding_box,
1613 max_pix_error=max_pix_error,
1614 degree=degree,
1615 max_inv_pix_error=max_inv_pix_error,
1616 inv_degree=inv_degree,
1617 npoints=npoints,
1618 crpix=crpix,
1619 projection=projection,
1620 matrix_type='CD',
1621 verbose=verbose
1622 )
1624 return hdr

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/gwcs/wcs.py:1797, in WCS._to_fits_sip(self, celestial_group, keep_axis_position, bounding_box, max_pix_error, degree, max_inv_pix_error, inv_degree, npoints, crpix, projection, matrix_type, verbose)
1794 if (xmax - xmin) < 1 or (ymax - ymin) < 1:
1795 raise ValueError("Bounding box is too small for fitting a SIP polynomial")
-> 1797 lon, lat = transform(crpix1, crpix2)
1799 # Now rotate to native system and deproject. Recall that transform
1800 # expects pixels in the original coordinate system, but the SIP
1801 # transform is relative to crpix coordinates, thus the initial shift.
1802 ntransform = ((Shift(crpix1) & Shift(crpix2)) | transform
1803 | RotateCelestial2Native(lon, lat, 180)
1804 | sky2pix_proj)

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:1136, in Model.call(self, *args, **kwargs)
1131 # prepare for model evaluation (overridden in CompoundModel)
1132 evaluate, inputs, broadcasted_shapes, kwargs = self._pre_evaluate(
1133 *args, **kwargs
1134 )
-> 1136 outputs = self._generic_evaluate(evaluate, inputs, fill_value, with_bbox)
1138 # post-process evaluation results (overridden in CompoundModel)
1139 return self._post_evaluate(
1140 inputs, outputs, broadcasted_shapes, with_bbox, **kwargs
1141 )

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:1098, in Model._generic_evaluate(self, evaluate, _inputs, fill_value, with_bbox)
1096 outputs = bbox.evaluate(evaluate, _inputs, fill_value)
1097 else:
-> 1098 outputs = evaluate(_inputs)
1099 return outputs

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:3352, in CompoundModel._pre_evaluate..evaluate(_inputs)
3351 def evaluate(_inputs):
-> 3352 return self._evaluate(*_inputs, **kwargs)

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:3380, in CompoundModel._evaluate(self, *args, **kw)
3378 if op != "fix_inputs":
3379 if op != "&":
-> 3380 leftval = self.left(*args, **kw)
3381 if op != "|":
3382 rightval = self.right(*args, **kw)

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:1136, in Model.call(self, *args, **kwargs)
1131 # prepare for model evaluation (overridden in CompoundModel)
1132 evaluate, inputs, broadcasted_shapes, kwargs = self._pre_evaluate(
1133 *args, **kwargs
1134 )
-> 1136 outputs = self._generic_evaluate(evaluate, inputs, fill_value, with_bbox)
1138 # post-process evaluation results (overridden in CompoundModel)
1139 return self._post_evaluate(
1140 inputs, outputs, broadcasted_shapes, with_bbox, **kwargs
1141 )

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:1098, in Model._generic_evaluate(self, evaluate, _inputs, fill_value, with_bbox)
1096 outputs = bbox.evaluate(evaluate, _inputs, fill_value)
1097 else:
-> 1098 outputs = evaluate(_inputs)
1099 return outputs

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:3352, in CompoundModel._pre_evaluate..evaluate(_inputs)
3351 def evaluate(_inputs):
-> 3352 return self._evaluate(*_inputs, **kwargs)

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:3380, in CompoundModel._evaluate(self, *args, **kw)
3378 if op != "fix_inputs":
3379 if op != "&":
-> 3380 leftval = self.left(*args, **kw)
3381 if op != "|":
3382 rightval = self.right(*args, **kw)

[... skipping similar frames: Model.__call__ at line 1136 (2 times), Model._generic_evaluate at line 1098 (2 times), CompoundModel._pre_evaluate.<locals>.evaluate at line 3352 (2 times), CompoundModel._evaluate at line 3380 (1 times)]

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:3380, in CompoundModel._evaluate(self, *args, **kw)
3378 if op != "fix_inputs":
3379 if op != "&":
-> 3380 leftval = self.left(*args, **kw)
3381 if op != "|":
3382 rightval = self.right(*args, **kw)

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:1136, in Model.call(self, *args, **kwargs)
1131 # prepare for model evaluation (overridden in CompoundModel)
1132 evaluate, inputs, broadcasted_shapes, kwargs = self._pre_evaluate(
1133 *args, **kwargs
1134 )
-> 1136 outputs = self._generic_evaluate(evaluate, inputs, fill_value, with_bbox)
1138 # post-process evaluation results (overridden in CompoundModel)
1139 return self._post_evaluate(
1140 inputs, outputs, broadcasted_shapes, with_bbox, **kwargs
1141 )

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:1098, in Model._generic_evaluate(self, evaluate, _inputs, fill_value, with_bbox)
1096 outputs = bbox.evaluate(evaluate, _inputs, fill_value)
1097 else:
-> 1098 outputs = evaluate(_inputs)
1099 return outputs

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:3352, in CompoundModel._pre_evaluate..evaluate(_inputs)
3351 def evaluate(_inputs):
-> 3352 return self._evaluate(*_inputs, **kwargs)

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:3387, in CompoundModel._evaluate(self, args, **kw)
3384 rightval = None
3386 else:
-> 3387 leftval = self.left((args[: self.left.n_inputs]), **kw)
3388 rightval = self.right(*(args[self.left.n_inputs :]), **kw)
3390 if op != "|":

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:424, in call(self, model_set_axis, with_bounding_box, fill_value, equivalencies, inputs_map, *inputs, **new_inputs)
415 args = ("self",)
416 kwargs = {
417 "model_set_axis": None,
418 "with_bounding_box": False,
(...)
421 "inputs_map": None,
422 }
--> 424 new_call = make_function_with_signature(
425 call, args, kwargs, varargs="inputs", varkwargs="new_inputs"
426 )
428 # The following makes it look like call
429 # was defined in the class
430 update_wrapper(new_call, cls)

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:401, in _ModelMeta._handle_special_methods..call(self, *inputs, **kwargs)
399 def call(self, *inputs, **kwargs):
400 """Evaluate this model on the supplied inputs."""
--> 401 return super(cls, self).call(*inputs, **kwargs)

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:1132, in Model.call(self, *args, **kwargs)
1129 fill_value = kwargs.pop("fill_value", np.nan)
1131 # prepare for model evaluation (overridden in CompoundModel)
-> 1132 evaluate, inputs, broadcasted_shapes, kwargs = self._pre_evaluate(
1133 *args, **kwargs
1134 )
1136 outputs = self._generic_evaluate(evaluate, inputs, fill_value, with_bbox)
1138 # post-process evaluation results (overridden in CompoundModel)

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:978, in Model._pre_evaluate(self, *args, **kwargs)
973 """
974 Model specific input setup that needs to occur prior to model evaluation
975 """
977 # Broadcast inputs into common size
--> 978 inputs, broadcasted_shapes = self.prepare_inputs(*args, **kwargs)
980 # Setup actual model evaluation method
981 parameters = self._param_sets(raw=True, units=True)

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:2126, in Model.prepare_inputs(self, model_set_axis, equivalencies, *inputs, **kwargs)
2122 self._validate_input_shapes(inputs, self.inputs, model_set_axis)
2124 inputs_map = kwargs.get("inputs_map", None)
-> 2126 inputs = self._validate_input_units(inputs, equivalencies, inputs_map)
2128 # The input formatting required for single models versus a multiple
2129 # model set are different enough that they've been split into separate
2130 # subroutines
2131 if self._n_models == 1:

File ~/miniconda3/envs/roman-data-workshop-env/lib/python3.10/site-packages/astropy/modeling/core.py:2222, in Model._validate_input_units(self, inputs, equivalencies, inputs_map)
2216 if (
2217 not self.input_units_allow_dimensionless[input_name]
2218 and input_unit is not dimensionless_unscaled
2219 and input_unit is not None
2220 ):
2221 if np.any(inputs[i] != 0):
-> 2222 raise UnitsError(
2223 f"{name}: Units of input '{self.inputs[i]}',"
2224 " (dimensionless), could not be converted to required "
2225 f"input units of {input_unit} "
2226 f"({input_unit.physical_type})"
2227 )
2228 return inputs

UnitsError: Shift: Units of input 'x', (dimensionless), could not be converted to required input units of pix (unknown)

[nden]

@lznakano This is a bug (or feature) of astropy.models and we are looking into work arounds or fixes.

[lznakano]

Hi Nadia, Thanks for your update. Best, Lijun On Mar 21, 2023, at 6:14 AM, Nadia Dencheva ***@***.******@***.***>> wrote: @lznakano<https://github.com/lznakano> This is a bug (or feature) of astropy.models and we are looking into work arounds or fixes. — Reply to this email directly, view it on GitHub<#445 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AC3NG7NTBGP7XLTYC3OK54LW5GSSHANCNFSM6AAAAAAVZKFUXI>. You are receiving this because you were mentioned.Message ID: ***@***.***>