Saving scene resampled to EPSG4326 (longlat) fails with ValueError: Could not determine pixel size from projection name 'epgs4326europa' (Unknown)

[gerritholl]

When resampling a scene to an area that has pixel sizes defined in long/lat, such as EPSG 4326, saving the dataset fails with a ValueError.

Code example:

from pyresample import create_area_def
from pyproj import CRS
from satpy import Scene
from satpy.utils import debug_on; debug_on()
sc = Scene(
        filenames=["/media/nas/x21308/scratch/hrpt_metop03_20210323_1809_12327.l1b"],
        reader=["avhrr_l1b_aapp"])
sc.load(["4"])
ar = create_area_def(
        (nm:="epgs4326europa"),
        CRS.from_epsg(4326),
        resolution=1/128,
        area_extent=(-20, 35, 20, 55),
        proj_id=nm)
ls = sc.resample(ar)
ls.save_dataset("4",
        "/tmp/test.tif",
        writer="ninjotiff",
        physic_unit="C",
        sat_id=7900014,
        chan_id=900015,
        data_cat="PORN",
        nbits=8,
        data_source="HRPT",
        ch_min_measurement_unit=40,
        ch_max_measurement_unit=-87.5)

Full output including traceback:

[DEBUG: 2021-10-04 15:57:59 : satpy.readers.yaml_reader] Reading ('/data/gholl/checkouts/satpy/satpy/etc/readers/avhrr_l1b_aapp.yaml',)
[DEBUG: 2021-10-04 15:57:59 : satpy.readers.yaml_reader] Assigning to avhrr_l1b_aapp: ['/media/nas/x21308/scratch/hrpt_metop03_20210323_1809_12327.l1b']
[DEBUG: 2021-10-04 15:57:59 : satpy.readers.aapp_l1b] Reading time 0:00:00.003103
[DEBUG: 2021-10-04 15:57:59 : satpy.composites.config_loader] Looking for composites config file avhrr-3.yaml
[DEBUG: 2021-10-04 15:57:59 : satpy.composites.config_loader] Looking for composites config file visir.yaml
[DEBUG: 2021-10-04 15:57:59 : satpy.readers.yaml_reader] No coordinates found for DataID(name='longitude', resolution=1050, modifiers=())
[DEBUG: 2021-10-04 15:57:59 : satpy.readers.yaml_reader] No coordinates found for DataID(name='latitude', resolution=1050, modifiers=())
[DEBUG: 2021-10-04 15:57:59 : satpy.scene] Resampling DataID(name='4', wavelength=WavelengthRange(min=10.3, central=10.8, max=11.3, unit='µm'), resolution=1050, calibration=<calibration.brightness_temperature>, modifiers=())
[INFO: 2021-10-04 15:57:59 : satpy.scene] Not reducing data before resampling.
[INFO: 2021-10-04 15:57:59 : satpy.resample] Using default KDTree resampler
[DEBUG: 2021-10-04 15:57:59 : satpy.resample] Check if ./resample_lut-f3500887016a9e9a9b23b19c6fedf95a426076bb.npz exists
[DEBUG: 2021-10-04 15:57:59 : satpy.resample] Computing kd-tree parameters
/data/gholl/checkouts/pyresample/pyresample/kd_tree.py:1012: DeprecationWarning: `np.float` is a deprecated alias for the builtin `float`. To silence this warning, use `float` by itself. Doing this will not modify any behavior and is safe. If you specifically wanted the numpy scalar type, use `np.float64` here.
Deprecated in NumPy 1.20; for more details and guidance: https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations
  input_coords = input_coords.astype(np.float)
/data/gholl/checkouts/pyresample/pyresample/kd_tree.py:1034: DeprecationWarning: `np.int` is a deprecated alias for the builtin `int`. To silence this warning, use `int` by itself. Doing this will not modify any behavior and is safe. When replacing `np.int`, you may wish to use e.g. `np.int64` or `np.int32` to specify the precision. If you wish to review your current use, check the release note link for additional information.
Deprecated in NumPy 1.20; for more details and guidance: https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations
  radius=self.radius_of_influence, dtype=np.int,
[DEBUG: 2021-10-04 15:57:59 : satpy.resample] Resampling where-9f3f1f4d3c037162a3d408d41ea4566f
[DEBUG: 2021-10-04 15:57:59 : satpy.writers] Reading ['/data/gholl/checkouts/satpy/satpy/etc/writers/ninjotiff.yaml']
/data/gholl/checkouts/pyninjotiff/pyninjotiff/tifffile.py:154: UserWarning: failed to import the optional _tifffile C extension module.
Loading of some compressed images will be slow.
Tifffile.c can be obtained at http://www.lfd.uci.edu/~gohlke/
  warnings.warn(
[DEBUG: 2021-10-04 15:58:00 : satpy.writers] Enhancement configuration options: [{'name': 'stretch', 'method': <function stretch at 0x7fbb6ec2ac10>, 'kwargs': {'stretch': 'linear'}}]
[DEBUG: 2021-10-04 15:58:00 : trollimage.xrimage] Applying stretch linear with parameters {}
[DEBUG: 2021-10-04 15:58:00 : trollimage.xrimage] Perform a linear contrast stretch.
[DEBUG: 2021-10-04 15:58:00 : trollimage.xrimage] Calculate the histogram quantiles:
[DEBUG: 2021-10-04 15:58:00 : trollimage.xrimage] Left and right quantiles: 0.005 0.005
[INFO: 2021-10-04 15:58:00 : pyninjotiff.ninjotiff] Will generate single band product
/data/gholl/mambaforge/envs/py39/lib/python3.9/site-packages/pyproj/crs/crs.py:1256: UserWarning: You will likely lose important projection information when converting to a PROJ string from another format. See: https://proj.org/faq.html#what-is-the-best-format-for-describing-coordinate-reference-systems
  return self._crs.to_proj4(version=version)
/data/gholl/mambaforge/envs/py39/lib/python3.9/site-packages/pyproj/crs/crs.py:1256: UserWarning: You will likely lose important projection information when converting to a PROJ string from another format. See: https://proj.org/faq.html#what-is-the-best-format-for-describing-coordinate-reference-systems
  return self._crs.to_proj4(version=version)
Traceback (most recent call last):
  File "/data/gholl/checkouts/protocode/mwe/ninjotiff-crash.py", line 16, in <module>
    ls.save_dataset("4",
  File "/data/gholl/checkouts/satpy/satpy/scene.py", line 1037, in save_dataset
    return writer.save_dataset(self[dataset_id],
  File "/data/gholl/checkouts/satpy/satpy/writers/ninjotiff.py", line 206, in save_dataset
    return super(NinjoTIFFWriter, self).save_dataset(
  File "/data/gholl/checkouts/satpy/satpy/writers/__init__.py", line 809, in save_dataset
    return self.save_image(img, filename=filename, compute=compute, fill_value=fill_value, **kwargs)
  File "/data/gholl/checkouts/satpy/satpy/writers/ninjotiff.py", line 178, in save_image
    return nt.save(img, filename, data_is_scaled_01=True, compute=compute, **kwargs)
  File "/data/gholl/checkouts/pyninjotiff/pyninjotiff/ninjotiff.py", line 560, in save
    return write(data, filename, area_def, ninjo_product_name, **kwargs)
  File "/data/gholl/checkouts/pyninjotiff/pyninjotiff/ninjotiff.py", line 665, in write
    ninjo_nav_parameters(options, area_def)
  File "/data/gholl/checkouts/pyninjotiff/pyninjotiff/ninjotiff.py", line 582, in ninjo_nav_parameters
    _get_pixel_size(options['projection'], area_def)
  File "/data/gholl/checkouts/pyninjotiff/pyninjotiff/ninjotiff.py", line 311, in _get_pixel_size
    raise ValueError(
ValueError: Could not determine pixel size from projection name 'epgs4326europa' (Unknown)

[gerritholl]

Looking at the source code, this would appear to be closely related to #25.

[gerritholl]

The problem can be circumvented by using proj_id=EQC_PLAT.