Help with weird uxarray, matplotlib, and orthographic plot

@mathomp4

Today I was trying out different things with uxarray and some data and found an...oddity. With the bokeh backend, I get a nice pretty image with an Orthographic projection:

but when I try and use the matplotlib backend:

Does anyone know what I might be doing wrong? My "relevant" code is:

import uxarray as ux
import geoviews as gv
import geoviews.feature as gf
import cartopy
import cartopy.feature as cf
import cartopy.crs as ccrs
import holoviews as hv

graticules = cf.NaturalEarthFeature(
    category='physical',
    name='graticules_15',
    scale='50m')

ofeatures = gf.coastline(
    projection=ccrs.Orthographic(), line_width=1, scale="50m"
) * gf.borders(
    projection=ccrs.Orthographic(), line_width=1, scale="50m"
) * gv.Feature(graticules, group='Lines')

ortho_plot = uxds['SLP'][0].plot.polygons(
    rasterize=True, 
    cmap='viridis', 
    backend='matplotlib', 
    projection=ccrs.Orthographic(),
).opts(
    global_extent=True,
    xaxis=None,
    yaxis=None 
) * ofeatures

Just the backend change in ortho_plot is the differences between these two. Note: This is a mix of uxarray examples and Gemini/ChatGPT/whatever so I freely admit I probably did something stupid!

Originally posted by @mathomp4 in #1488

@erogluorhan

@erogluorhan Here is a link to the file

It's pretty small to make things easy.

Whoops. I also forgot one sort of crucial thing in the Python snippet:

file_path = r"c24.nc4"
uxds = ux.open_dataset(file_path, file_path)

I mean, you need to open the file 😄

@mathomp4

The problem seems related to gv.Feature(graticules, group="Lines") using the Natural Earth graticules_15 feature. The base UXarray polygon plot, gf.coastline(), and gf.borders() all render correctly with the matplotlib backend but adding the graticules feature causes the rendering to collapse.

field = uxds["SLP"][0].plot.polygons(
    rasterize=True,
    cmap="viridis",
    backend="matplotlib",
    projection=ccrs.Orthographic()
).opts(
    xaxis=None,
    yaxis=None,
)
field
field * gf.coastline(scale="50m")
field * gf.borders(scale="50m")
field * gv.Feature(graticules, group="Lines")

As a workaround, I was able to get the expected result by avoiding gv.Feature(graticules_15) and instead adding gridlines directly through the Cartopy axis using ax.gridlines(...) after rendering:

renderer = hv.renderer("matplotlib")
overlay = (
    field
    * gf.coastline(scale="50m")
    * gf.borders(scale="50m")
)
mpl_obj = renderer.get_plot(overlay)

mpl_obj.handles["axis"].gridlines(
    draw_labels=False,
    linewidth=0.6
)

This suggests the issue may be somewhere in the GeoViews/Cartopy feature overlay or clipping pipeline rather than in UXarray itself. Hopefully this helps @mathomp4 :)

@alioacar

@alioacar thanks a lot for looking into this and suggesting a workaround! I'll try to think about this case a bit more when I have some time.

Confirming, this looks like an upstream issue, I was able to reproduce it without using UXarray at all. See holoviz/geoviews#845 for more details!

Confirming, this looks like an upstream issue, I was able to reproduce it without using UXarray at all. See holoviz/geoviews#845 for more details!

Thanks for pointing this out. It seems like our fix still holds

@alioacar

Confirming, this looks like an upstream issue, I was able to reproduce it without using UXarray at all. See holoviz/geoviews#845 for more details!

Thanks for pointing this out. It seems like our fix still holds

So, are you suggesting that we should still put together a workaround, maybe something close to what @alioacar suggested? I think I lean more towards waiting for the fix on the holoviz/geoviews/issues/845.

@erogluorhan

I initially thought this was a more complex overlay issue. @erogluorhan I agree that it's better waiting for the fix to be merged

I misspoke — I was thinking of #1515 which fixed Bokeh Orthographic plots, but that's unrelated. The matplotlib+graticules issue is purely upstream in geoviews (holoviz/geoviews#845). Agree with you: wait for holoviz/geoviews#846 to merge.

@rajeeja

Okay, perfect, thanks for clarifying @rajeeja and @alioacar !

Let's keep this open until the geoviews fix is released, and then we can give this a second try and hopefully close it once confirmed things work.

Test it again once geoviews 1.15.2 is released and close if it looks good.

Test it again once geoviews 1.15.2 is released and close if it looks good.

Will do! Hopefully it is released soon :)

@mathomp4

@mathomp4 , geoviews 1.15.2 is now released and we closed this. Please feel free to reopen if you test it and think it is not resolved.

@erogluorhan

@erogluorhan Sorry it took me so long, but I can see things are now good with geoviews 1.16.0. Thanks!

29. @erogluorhan Sorry it took me so long, but I can see things are now good with geoviews 1.16.0. Thanks!

No worries at all; thanks for confirming it works! Best,

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Help with weird uxarray, matplotlib, and orthographic plot #1489

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Help with weird uxarray, matplotlib, and orthographic plot #1489

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mathomp4 commented on Apr 13, 2026

mathomp4 commented on Apr 13, 2026

alioacar commented on May 15, 2026

erogluorhan commented on May 18, 2026

Sevans711 commented on Jun 29, 2026

rajeeja commented on Jun 30, 2026

erogluorhan commented on Jun 30, 2026

alioacar commented on Jul 1, 2026

rajeeja commented on Jul 1, 2026

erogluorhan commented on Jul 1, 2026

erogluorhan commented on Sep 2, 2026

mathomp4 commented on Sep 3, 2026

erogluorhan commented on Oct 27, 2026

mathomp4 commented on Nov 3, 2026

erogluorhan commented on Nov 3, 2026

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