Creation of composites using sunz_corrected modifier fails with VIIRS SDR data

[pnuu]

Describe the bug
Creating any of the built-in composites using sunz_corrected modifier fails for VIIRS SDR data with the traceback shown below.

To Reproduce

from satpy import Scene
import glob
fnames = glob.glob('*b37299*')
glbl = Scene(reader='viirs_sdr', filenames=fnames) 
glbl.load(['natural_color'])  # Also 'natural_color' and 'natural_color_lowres' fail
lcl = glbl.resample('euro4', resampler='nearest')

Crashes when resampling is run.

Expected behavior
A clear and concise description of what you expected to happen.

Actual results

ValueError                                Traceback (most recent call last)
<ipython-input-7-4113a12cb6fe> in <module>
----> 1 lcl = glbl.resample('EPSG_3035_4km', resampler='nearest')

~/Software/pytroll/packages/satpy/satpy/scene.py in resample(self, destination, datasets, generate, unload, resampler, **resample_kwargs)
    996         # multiple resolutions, etc.)
    997         if generate:
--> 998             keepables = new_scn.generate_composites()
    999         else:
   1000             # don't lose datasets that we may need later for generating

~/Software/pytroll/packages/satpy/satpy/scene.py in generate_composites(self, nodes)
    799             nodes = set(self.dep_tree.trunk(nodes=required_nodes)) - \
    800                 set(self.datasets.keys())
--> 801         return self._read_composites(nodes)
    802 
    803     def _remove_failed_datasets(self, keepables):

~/Software/pytroll/packages/satpy/satpy/scene.py in _read_composites(self, compositor_nodes)
    773         keepables = set()
    774         for item in compositor_nodes:
--> 775             self._generate_composite(item, keepables)
    776         return keepables
    777 

~/Software/pytroll/packages/satpy/satpy/scene.py in _generate_composite(self, comp_node, keepables)
    748             composite = compositor(prereq_datasets,
    749                                    optional_datasets=optional_datasets,
--> 750                                    **self.attrs)
    751 
    752             cid = DatasetID.from_dict(composite.attrs)

~/Software/pytroll/packages/satpy/satpy/composites/viirs.py in __call__(self, datasets, optional_datasets, **info)
     98         else:
     99             vis, sensor_aa, sensor_za, solar_aa, solar_za = self.check_areas(
--> 100                 datasets + optional_datasets)
    101             # get the dask array underneath
    102             sensor_aa = sensor_aa.data

ValueError: too many values to unpack (expected 5)

Adding a debugger call just before the failure and printing the standard_names of the datasets returned by check_areas() it seems that there are multiple instances of sensor/satellite azimuth and zenith angles:

(Pdb) print('\n'.join([dset.attrs['standard_name'] for dset in self.check_areas(datasets + optional_datasets)]))
toa_bidirectional_reflectance
sensor_azimuth_angle
sensor_zenith_angle
solar_azimuth_angle
solar_zenith_angle
sensor_azimuth_angle
sensor_zenith_angle
solar_azimuth_angle
solar_zenith_angle

Environment Info:

• SatPy Version: 0.11.1
• Conda, Python 3.6

[djhoese]

@pnuu Are you sure you don't have some custom configuration messing with this?

The composites, which need to be specially configured if they use I band data, work for me. I am able to request scn.load(['natural_color']) for VIIRS SDR data and have it produced with no issue. Granted my data is from 2012, but that shouldn't make a difference. I am using the default satpy configurations.

[pnuu]

Indeed. It was a modifier I thought I had copy&pasted to my own viirs.yaml from the built-ins:

modifiers:
  rayleigh_corrected:
    compositor: !!python/name:satpy.composites.viirs.ReflectanceCorrector
    dem_filename: CMGDEM.hdf
    prerequisites:
    - satellite_azimuth_angle
    - satellite_zenith_angle
    - solar_azimuth_angle
    - solar_zenith_angle

After changing the modifier name to rayleigh_corrected_crefl it didn't crash anymore.

Closing: user error :-)