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catchyid

Fluid Rendering Questions?

Hi,

I see two SOP nodes that convert Fluid particles to a renderable geometry:

1) Particle Fluid Surface: can produce polygon, VDB, ... AND it has automatic attributes transfer from the particles to the created geometry

2) VDB From Particle Fluid: creates VDB obviously...

Although "Particle Fluid Surface" seems more advanced, can produce many output formats, and used by built-in shelf-tools, the documentation recommends "VDB From Particle Fluid" in (http://www.sidefx.com/docs/houdini15.5/nodes/sop/vdbfromparticlefluid) as follows:

"This node replaces the Particle Fluid Surface node. This node is much faster, uses less memory, gives smoother (less lumpy) results, and has much better "sheeting" (narrow tendrils will appear as connected fluid, instead of a line of droplets)."

a- I am wondering what other people are using in production, i.e. "Particle Fluid Surface" or "VDB From Particle Fluid"?

b- In general, is it better to render the particle as polygonal surface OR VDB? 

FYI, I am working on lava simulation (not sure if it's relevant to the question, but still worth mentioning )

Thanks :)

 

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Hi,

I did a quick check on the mentioned nodes, here's what I discovered:

  • It's possible that the docs was referring to H14's Particle Fluid Surface SOP. Back in H14, that SOP was not an HDA (you cannot dive into it).
  • In the newer versions, the Particle Fluid Surface SOP became an HDA, and once you dive inside, you'll see that the default Method of "Average Position" is internally using the recommended VDB From Particle Fluid SOP. A mention of it can also be seen in a more complete description for the Method parameter in the docs.

On my last liquids project, I did use the new Particle Fluid Surface SOP and rendered it as a mesh. Here's a bit of what it looked like in flipbook:
fluid_surface.gif

I guess it would depend on what look you're going after. Maybe for pretty solid/opague stuff, go with meshed particles. But for softer/smokey bits, go for VDBs/Volumes? As for lava, I usually see samples that looks like meshed particles.

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Thanks Jeff... I need to learn to dive inside nodes :) I think I will try meshed particles, I "think" it will give good result as you suggested :) Alright, once more, thanks for your help :)

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