meshing liquid

[harvr]

hi
when meshing liquid for large ocean scene, is there a way NOT to mesh the "droplets/ tendrils of liquid" that are "in the air" , and not part of the fluid body?

kind regards

Harv

[Svetlin.Nikolov]

Hey,

If your simulation is already done, sounds like a job for the Render Cutter - https://docs.chaosgroup.com/display/...ing-Parameters

If your camera is away, you could also try something else that would not require you to place and animate geometries - in that same rollout, there is the Mesh Smooth section; There you could use the Liquid particles in order to help the voxel mesher, which usually is a scenario you would need for smaller scale fluid, but in this case - try enabling Use Liquid Particles and shrink the Particle Size option to 0. This would either remove or shrink the entire liquid surface with 1 voxel, so it could make these stray droplets disappear from your render.

A third option (btw, it's not a problem to mix any two or three of these) would be to increase the Isosurface Level parameter from that same rollout - check out the comparison pics on the docs page for what it does. This way you could also thin out the liquid and maybe finish it off by combining with one of the two methods above.

In case you can afford running a new simulation, you could also use a Particle Tuner to kill these particles, but you have to define the criteria for them to die. E.g. their position along the Z axis is too high above the ocean level...

Give these a try and ping us if you have any trouble!

[harvr]

Hey Svetlin
thanks for the answers, i think Particle Tuner is best way, but need to wait for studio update after COVID

ill try other methods in meantime

cheers

Harv

[Svetlin.Nikolov]

Ah, some more thoughts about how yhese would work during animation rendering - the mesh smoothing and isosurface level approaches will erode the entire mesh surface, while the render cutter will make particles disappear during animation and then eventually reapper when they come out of the cutter volume. Similarly, deleting the particles via a tuner will also make them disappear in animation, but if this cases visible weirdness, then a possible way to do it would be not to delete particles, but to just teduce their Z axis velocity is they are already moving up along the Z axis....

[harvr]

ok, so basically , the particle only "deletes" when it is within a "condition" and therefore will reappear when it doesn't fill the "condition" anymore.
correct?

[Svetlin.Nikolov]

Nah, if you delete a particle with a Tuner, it's pretty much dead forever, but if you choose to hide it at render time, it can reappear when it goes outside the render cutter

[harvr]

ok gotcha ,
thanks Svetlin!!

......can the Tuner be used post Sim too? its a very powerful way of deleting particles in Houdini post sim

[Svetlin.Nikolov]

It's simulation time only. Right now for rendering you have the cutter geometry available for both fire/smoke and the Particle Shader, and in the Particle Shader there are also more options that allow you to drop particles from the render - the Subgroup, Count Multiplier, Size Multiplier can be used to shrink particles and can also do this for aged particles as well. Would be better to have more control over this though, we're thinking of what to add

[harvr]

thanks Svetlin
more controls is always better lol

[Ivaylo Katev]

As i remember, the mesher analyses what part of the liquid is isolated droplets, and what part is the solid liquid body, this is used when the ocean extension is built. If such a feature can be useful, it can be implemented relatively easy, using the already existing information.

[harvr]

yes, it would be useful for big scale sims, where the liquid doesn't need to be meshed
anything "droplet" or "stringy" liquid that is "detached" quite away from main body of liquid i usually want to cull

[Svetlin.Nikolov]

Indeed, we have something larger in mind that does not only concern the mesher, so I think this will fit there as well...

[harvr]

oh, do tell please lol~
any love for large scale foam/splash rendering?

[Svetlin.Nikolov]

Sorry, can't tell, but if you need anything added or changed, please make sure to let us know..

[harvr]

understandable

thanks