How to get epsg or proj crs?

[rsignell-usgs]

I'm trying to use rioxarray.open_rasterio to create an xarray dataarray from a COG and then use hvplot to visualize it, which takes a Cartopy crs argument.

This is a bit embarrassing but I can't figure out how to obtain a crs proj or epsg code from rioxarray.open_rasterio.

If I use xarray.open_rasterio I have .crs, which gives me the proj or epsg code, but with rioxarray.open_rasterio I see spatial_ref, which contains wkt.

Example:

# from https://openaerialmap.org/
cog_url = (
    "https://oin-hotosm.s3.amazonaws.com/"
    "5d7dad0becaf880008a9bc88/0/5d7dad0becaf880008a9bc89.tif"
)
import xarray as xr
xr.open_rasterio(cog_url).crs

yields:

'+init=epsg:3857'

But rioxarray:

import rioxarray as rx
rioxarray.open_rasterio(cog_url).spatial_ref

yields:

<xarray.DataArray 'spatial_ref' ()>
array(0)
Coordinates:
    spatial_ref  int64 0
Attributes:
    spatial_ref:  PROJCS["WGS 84 / Pseudo-Mercator",GEOGCS["WGS 84",DATUM["WG...
    crs_wkt:      PROJCS["WGS 84 / Pseudo-Mercator",GEOGCS["WGS 84",DATUM["WG...

I think I'm definitely missing something here. 😕

[snowman2]

I think what you want is:

xds.rio.crs.to_proj4()

https://corteva.github.io/rioxarray/html/examples/crs_management.html

[snowman2]

The documentation is a work in progress. If you have any recommendations, it would be helpful to hear another perspective.

[snowman2]

Closing as I believe your issue has been resolved. If not, feel free to reopen or just continue to ask questions.

[rsignell-usgs]

Yes, @snowman2, that indeed solved my problem! I don't know what documentation I was looking at, because I could have sworn I searched on crs and didn't see all that useful information. Thanks for being patient and your polite response to my question. I'll try to be more careful next time.

[snowman2]

Glad to hear it worked well for you! No worries - I miss things quite a bit myself :)