Georeferencing follow-up issue

[kmuehlbauer]

to not forget the items from #25:

• [x] Move cartesian coordinate definition into model see https://github.com/openradar/xradar/pull/28#discussion_r981978559
• [ ] use model functionality to create Dataset
• [ ] docstring fixes
• [x] use site-coordinates (lat, lon, alt) to calculate final bin aeqd coordinates #87
• [x] add spatial_ref to Dataset/DataArray on georeferencing #87
• [ ] tbc

[mgrover1]

Thanks for putting these together @kmuehlbauer

[mgrover1]

For georeferencing... @kmuehlbauer what would you think if we had an optional cartopy dependency? To deal with these projections?

[kmuehlbauer]

@mgrover1 Do you refer to map-making? Could you elaborate a bit more with regard to what functionality you have in mind?

[mgrover1]

I am thinking in terms of projecting data as well - see the MetPy functionality here https://unidata.github.io/MetPy/latest/examples/XArray_Projections.html

[kmuehlbauer]

Yes, I see, they use an accessor to get a cartopy crs object.

From my perspective we would just need to add the aeqd cartopy crs to Dataset/DataArray when creating xyz-coordinates if cartopy is available.

[mgrover1]

Yup! That makes sense!

[mgrover1]

Sorry for the delay here @kmuehlbauer ... prepping for our ARM/ASR meeting next week.

[kmuehlbauer]

No worries @mgrover1. It's great we are this far already.

[kmuehlbauer]

From my perspective we would just need to add the aeqd cartopy crs to Dataset/DataArray when creating xyz-coordinates if cartopy is available.

@mgrover1 I've though about that the last days and tinkered a bit with pyproj. I've ended up with a workflow where we can use pyproj to:

• georeference the data using the derived latitude-dependend earth-radius
• write_crs (as spatial_ref - Variable)
• get_crs (retrieve spatial_ref or create on the fly if not available)

The users would be able to wrap that into a cartopy.crs.Projection and use it for plotting with cartopy.

That would leave us with only pyproj/proj as additional dependencies. We could even make this optional. I'll see if I can workout a PR from that.

[kmuehlbauer]

@mgrover1 I've setup a PR with a minimal pyproj-based solution in #87.

[kmuehlbauer]

@mgrover1 We might close this issue and #25, as we have the basic workable georeferencing available now. WDYT?

[mgrover1]

Agreed! Let's do it.