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Node noob calling all node gurus.

I'm working with some simulated galaxy data at university and as an aside, I'm wondering if I can render it in Blender - however because it was legitimately simulated on a supercomputer there are a lot of data points. I've already cropped the data but I need to 'sparse out' the render by removing every nth point. I would like to do this non-destructively using nodes, but will fall back to python if that falls through.

enter image description here

enter image description here

Also, for some reason, my point-radius allocation isn't working.

Cheers!

Part II of the project is here.

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  • $\begingroup$ Hello ! You might want to explore the point cloud visualizer addon which is awesome to visualize point cloud data. It is paid for though. blendermarket.com/products/pcv The Set Point Radius node isn't working because it expects a Point Cloud native geometry type, and you seem to be using a mesh with vertices acting as a point cloud (not the same, and not optimized for extremely large number of items). What is the format of your input data ? $\endgroup$
    – Gorgious
    Apr 24, 2023 at 18:07
  • $\begingroup$ or you may remove randomly points. $\endgroup$
    – lemon
    Apr 24, 2023 at 18:27
  • $\begingroup$ "I would like to do this non-destructively using nodes" - why? This way the process will consume resources on each frame. $\endgroup$ Apr 24, 2023 at 21:41

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Are you working with vertices-data only? This setup would remove every nth vertices of a mesh.

EDIT: I have modified the setup based on user recommendations

enter image description here

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  • $\begingroup$ Hi Robert! That works great in edit mode, but when I switch back to object mode all the original points become visible again. Any ideas? $\endgroup$
    – Blenderman
    Apr 24, 2023 at 21:26
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    $\begingroup$ Why "Truncate"? Also it doesn't remove ever nth point, it keeps every nth point. $\endgroup$ Apr 24, 2023 at 21:40
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    $\begingroup$ Yup you can use an integer output in geometry nodes instead of the value + truncate nodes. And add a boolean invert between the modulo and the delete geometry node $\endgroup$
    – Gorgious
    Apr 25, 2023 at 9:32
  • $\begingroup$ @Blenderman Sorry, I have no idea why that happens. Could depend on your input data/mesh or other things. I tried a couple of primitives with this node setup and I did not have this problem. $\endgroup$
    – Robert L.
    Apr 25, 2023 at 18:54
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    $\begingroup$ One reason why maybe this doesn't work is that it uses ID node. If ID doesn't exist, it uses index, but if it does, it could as well be all zeroes. BTW, instead of using "NOT", perhaps a more readable (but maybe slower, I don't know) compare node could be used: personally, I would use "equal" in integer mode, to signal I'm expecting an integer as input, and compare with 0 explicitly, rather than rely on float to boolean conversion, which perhaps not everyone understands (0 is False, otherwise True). I admit though, there is something satisfying about converting values to boolean. $\endgroup$ Apr 25, 2023 at 19:18

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