[Maya/Phoenix FD] - Questions in regards to liquids, grid artifacts and re-simulation

[9k_JHT]

So I was playing around with resimulating liquids and apparently Phoenix FD doesn't support resimulation of grid size for liquids? I'm attempting to do this and I'm getting the following error messages -

// Warning: PhoenixFD: Grid Resimulation of Liquids may produce incorrect result! In liquid mode, only particles resimulation is supported! //
// Error: Phoenix FD: Resimulation size mismatch! //


Just looking for confirmation that this is the case now? Thanks.


---------Original Post Below--------
Got a few quick general questions for ya'll.

Below is an rough render of a fluid simulation I'm working with-



It's fluid running through a tube. Cell size is set to 0.200. Notice the heavy grid artifacts. I understand this is due to the grid size being fairly large. If I simulate again (not re-sim.. but a completely new sim) with a finer grid size, the fluid movements are completely different. I like everything about this simulation minus the grid lines.

Would resimulating this rough sim allow for the same fluid movements (distance covered, motion of the fluid), but with a finer grid where those artifacts aren't visible? I'm thinking it would, but I wanted to check before I spent the time to resim to make sure this would be the most optimal way to get rid of those artifacts? I've already attempted a render gizmo which gave off some funky results for me.

Best and thanks,
Clayton

[9k_JHT]

Sorry for the spam. Found the answer on this forum after hunting for a while -

"the liquid content can't be reismulated, only the foam and splash particles can"

Guess that rules out resimulating the fluid with a finer grid to keep the general motion, but eliminate grid lines. Guess I'll have to do a fresh simulation and mess with values to try and get the look/feel of the rough grided simulation but with a finer grid. Changing the units scale looks promising.

Thanks!

[Ivaylo Katev]

if this is the entire simulation, you can try to arrange the orientation of the simulator to be parallel to the movement direction.

[9k_JHT]

if this is the entire simulation, you can try to arrange the orientation of the simulator to be parallel to the movement direction.

Your suggestion worked well Ivaylo! I have another question for you in regards to re-Simulation. I have a liquid sim with splashes. Took a long time to simulate and there are way too many splashes that were generated. How would I go about resimulating a liquid simulation and be able to modify the particle generation threshold? I get a size-mismatch error when I attempt to resimulate and affect just the particles (splashes.. not the grid. Only changes the splash parameters and resimulating).

Unless there is a way to do this without re simulating? The end game is to push the particles to Alembic by exporting an Alembic cache of the nParticles I can create from the Simulation (there is an option in there that allows this inside the simulator. Don't know what it's called). If I can get the particle count down, separate the particles from the actual fluid mesh (both via alembic), I could then use a couple vray proxy objects to re-import the Alembic and completely circumvent having to use Phoenix FD to render (If rendering with Phoenix were an option I would use the foam shader and simply control the particle count from there).

Reason being is that the farm I am working through does not have Phoenix FD support and I'm trying to find other solutions to get my simulations data independent of Phoenix to be able to render with them. I've emailed Phoenix Support about getting the proper permissions for them to have access to a nightly build (as the simulation part of Phoenix FD is what requires a license.. not the render node part). Hopefully that gets green lit, but if not I'm trying to find other options.

Thanks for any help! You've been super helpful thus far and I know my questions probably seem like they keep on getting more ridiculous each time.

Cheers.

[Ivaylo Katev]

I get a size-mismatch error when I attempt to resimulate and affect just the particles

this sounds like a bug, as i understand you are using the official release, so we can't fix it, you have to simulate again the entire simulation. but don't think this is a big tragedy, in the most cases the foam and splash take the bigger part of the simulation and the resimulation is not quite faster compared to the full simulation.
about the rendering without phoenix, the usual way is krakatoa, if the farm supports it you can use it.

[9k_JHT]

this sounds like a bug, as i understand you are using the official release, so we can't fix it, you have to simulate again the entire simulation. but don't think this is a big tragedy, in the most cases the foam and splash take the bigger part of the simulation and the resimulation is not quite faster compared to the full simulation.
about the rendering without phoenix, the usual way is krakatoa, if the farm supports it you can use it.

Hmm. Yeah, I don't know which nightly version I was using when I simulated. As far as Krakatoa, I don't own that and am completely clueless on how to work with it/set it up. If I can separate the particles and get them into Alembic I'm golden, but outside of that I don't have many options due to time constraints/lack of knowledge with Krakatoa (will keep that in mind for next time). Will wait to hear back from Phoenix support. If they allow the farm access to Phoenix FD render nodes, the farm agreed to load it on their machines. Don't know how that works policy wise for Chaosgroup.

Thanks.

[Svetlin.Nikolov]

Sounds like a bug indeed. Re-sim in Maya with Adaptive grid on, right?

[9k_JHT]

Sounds like a bug indeed. Re-sim in Maya with Adaptive grid on, right?

Yeah. Adaptive grid was used for the original simulation. I opened up the original sim file (I do all my sims in dedicated scenes), checked the resim box, affect particles only, left UVW/Wave on (on by default), changed the splash values, and clicked the start button. I've gotten this error before when attempting to resim liquids, but after reading up some, the resimulation of liquids isn't possible in Phoenix (resimulating the grid is not possible I should clarify).

Dunno. I also might be losing my mind. I'll let you guys know too (should be in the requested feature thread but I'm putting it here), extracting the Phoenix data (like mesh and particles) and sticking them into native Maya shiz (straight nParticles and straight mesh) would be one hell of a treat.

Also... I'm confused why support for Phoenix/Maya isn't available for anything past Maya 2013 without going to the nightlies. This week has been an emotional roller-coaster trying to find a farm that supports Phoenix for current versions of Maya. You wizard devs probably have your reasons.

Edit: Also, also. Not trying to tell Chaosgroup how to live it's life, but it also might make sense to have a DL section for public (render farms) to be able to download Phoenix FD for render node purposes. Mad respect, love the software, the company and the support, but these things are making me scratch my head a little bit. Good chance I'm not seeing the whole picture. I drive the car around, I don't have to manage under the hood.

Okay. I'll get off my soapbox now. haha.

[Svetlin.Nikolov]

True that - farms only support the official Phoenix versions since the nightlies change... every night, and furthermore there hasn't been a Phoenix Maya release in more than 3 years so the nightlies are already way out of sync with what the farms supported. Not to mention the last official Phoenix for Maya didn't support V-Ray 3 because there wasn't one yet. I hope soon this will be fixed by having a new official Phoenix, but there's a lot of work left until that time.

Almost got to the resimulation thing - though I'm pretty sure if it gave you an error before, it wasn't by design - grid liquid resim is not supported in the sense that bad evil things may happen to the liquid if you try it, or at least the liquid won't be any more useful than the original sim. Size mismatch without changing the size most likely is a bug, though...

[Svetlin.Nikolov]

Hmm, can't break it with a simple scene, could I ask you for the scene again? You could also route it through support if it's not meant for everyone's eyes

[9k_JHT]

"Not to mention the last official Phoenix for Maya didn't support V-Ray 3 because there wasn't one yet"

Good point. I forgot for a second that one of Phoenix FD's greatest strengths is being so tightly compatible with Vray. That is after all why I went with Phoenix FD as opposed to Reel Flow (and the price). I think in my case, AWS might be something worth looking into. If a person sets up his/her own farm on the cloud, that avoids any software compatibility issues.

Thank you for your help!