Re: Pytroll/SatPy for EUMETCast

Ernst Lobsiger


I'am still an absolute Python newby, So what you recommend is out of reach :-).

SatPy is Pytroll integrated to a level where you can get results with 3 lines.
But this goes with less control. I have not yet found a way to make SatPy use
a provided TLE. It seems to download that from Internet whenever necessary.

Also I have an issue with "platforms.txt". Under certain conditions I can
not reproduce so far, my scripts show a need for that file in the DEBUG output.
The file seems not distributed with satpy or pyorbital. On the command line
it's easy to get the message that the platforms.txt is missing in PPP_CONFIG_DIR.
If PPP_CONFIG_DIR environmental varable is not set it Defaults to ...satpy/etc.

from pyorbital import tlefile
On the other hand the OLCI reader does read all 21 channels + tie_geometries
+ geo_coordinates + ...._instrument_data. It does not (yet?) understand
xdumanifest + time_coordinates + quality_flags + removed_pixels. The
DEBUG output does not show a need for a TLE or an attempt to download that.

Images are rather pale compared to what I get using SNAP4 convert.


Am 07.10.2018 11:48, schrieb simonproud:
Hi Ernst,
We have been using SatPy (and PyTroll before that) for some time to
generate the live satellite images on TV screens around our workplace. It's
an excellent tool!
One thing I would recommend is to only use SatPy to load the data, then to
do the processing yourself in numpy/xarrays. SatPy seems very slow at
calculating solar angles, so I prefer to link it to an external C-script
that can calculate the angles much faster, it saves us about 5 minutes of
processing time for the high res satellites, and a minute or two for
SEVIRI. You can still use the satpy composites to generate the final image,
just requires a bit of hacking!
We're also looking to use SatPy with OLCI/SLSTR NRT data, although we've
not done that yet. One thing I don't understand there is why PyOrbital is
needed, both OLCI and SLSTR granules contain geoinfo so I don't know why
there's a need to know the TLEs for Sentinel-3A/B. I presume I have missed
something obvious! ;-)
I may be going to the next SatPy workshop, so maybe see you there?

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