Control resolution of rasterized plots

I’m using ds.hvplot.quadmesh to project and visualise a heatmap of geospatial data. Due to the size of the data, I have to set rasterize=True. As far as I’m aware (and I may be wrong), the only way to control the spatial resolution of the rasterization process is to specify the height and width parameters in the arguments to the plotting function. This has the undesirable effect of making all the figure element (labels, bokeh widgets, etc) super small. It would be preferable if there were a way to control the downsampling process without changing the actual size of the plot. Is there something I’m missing or am I on to something? Cheers!

[tom-andersson]

Hmm, this is a bit of a dilemma. 3 would save people time on searching through HoloViews documentation while adding some nice additional functionality (e.g. reducing resolution to send a plot over email, etc). Having to manually set the height and width of the underlying raster (e.g. through option 2 or 1) is a bit unintuitive for new users. The extra flexibility afforded by 1 would be useful too, though.

3 would get my main vote, but 1 would be a nice plus (with a link to the appropriate HoloViews documentation). I guess you would have to ensure users didn’t supply both rasterize_factor and rasterize_args={'height': ..., 'width': ... at the same time though.

[jbednar]

The underlying rasterize() function provides those arguments, but I don’t think they are exposed in hvPlot. To get around that, you can try code like this sketch:

from holoviews.operation.datashader import rasterize
p = rasterize(ds.hvplot.quadmesh(
        x='lon', y='lat', z=variable,
        crs=crs, projection=projection,
        width=600, height=540, cmap=cmap,
        title=title, legend='bottom', 
        global_extent=False, project=True,
    ), plot_height=300, plot_width=300)