Web plotting when datapoints >> plot pixels

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Makie is pretty great for plotting big datasets, in particular the datashader functionality datashader · Makie

But in the case of WGLMakie, you would first have to send the dataset to the client, which could be gigabytes.

Over in the Python world the Datashader + Holoviews + Plotly combination has a different approach: Datashader produces an image which is rendered in Plotly, and Holoviews hooks up Plotly zoom events to rerender the image. Example: https://twitter.com/pepijndevos/status/1509948476586663937?s=19 Docs: Interactivity — Datashader v0.14.4

This way you’re only sending kilobytes of data to the client rather than gigabytes, but you can still zoom in on the data and see increased details.

I think it would definitely be possible and useful to have access to this approach for big data notebooks, but I haven’t quite figured out all the plumbing, so I thought I’d share what I got and maybe someone has better ideas.

Basically I use Makie to generate a static plot, and use show to turn it into a base64 encoded data URL. I then set this as an image on Plotly, and hook up the plotly_relayout event to send the plot bounds to Julia which I use to set the limits on the Makie plot.

But I haven’t actually managed to close the loop where Plotly updates with the new Makie plot.

Here is the notebook I’m playing around with: JuliaHub

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But in the case of WGLMakie, you would first have to send the dataset to the client, which could be gigabytes.

That’s not true, you’ll only send the final image!

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Then… what’s WebGL about it if it actually doesn’t render anything in the client?

I was actually trying to confirm how it works but if I open the web inspector after it loads it shows nothing and if I reload the page it stops working altogether…

I’d imagine for small datasets you would want it the other way. Where pixels >> datapoints you’d want to actually render on the client. You’d also very much want this behavior if you’re generating a static HTML page where you want to be able to zoom into plotted data. So now I have the opposite question…

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Can you open an issue with an MWE for when it stops working?

I’d imagine for small datasets you would want it the other way

I think you should wait until at least we actually publish this feature.
I’m planning to write a blogpost explaining all of this.

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ok thanks