ship in ocean in Ver 3.0

[baro]

Hi there,

tested the ship simulation from http://forums.chaosgroup.com/showthr...577#post685577, http://forums.chaosgroup.com/attachm...0&d=1458210865
works great in V3
tried to recreate the the simulation by borrowing the ship from the above scene, starting new simulator and copping the settings from the above simulations (not the presets, but keying in settings) were possible. some settings could not be replicated as the original scene opens with slightly different simulator settings interface.
example:
original scene:
new simulator:
the results were quite different. for the same grid size, cells count, foam/splash settings, the recreated simulations generated quite a bit larger frame files:
original:
new sim:
I'm guessing this must have to do with the Output settings. can someone please tell me what needs to be switched off form the those settings or should the reason for those large files (hence slow sim) is somewhere else?

does someone has the original ship scene (or simmilar) tuned up / optimised for the V3 core and is in position to share (posibly with units 1u=1m [not 1u=20cm very confusing for non-artistic stiffs like me])? this would be a BIG favor

thanks for the help in advance

[Ivaylo Katev]

the reworked scene is put in the help, try with it

[Svetlin.Nikolov]

It's not in the help yet, I will update it shortly.

[Svetlin.Nikolov]

Alright, so here are the updated scenes, but the page is still work in progress: https://docs.chaosgroup.com/display/...Example+Scenes

As for the specific ship scene - by default in Phoenix 3.0 the simulation exports much more particle systems and also mush more channels for each one of those, so the files will be bigger. You can turn off anything you don't need from the Output panel - Velocity if you don't need motion blur, IDs if you are not going to have slow motion effects, etc. You can check the docs site for more info.

Hope this helps, cheers!

[baro]

Thanks for the response Svetlin,
The scene from the link you posted does come with an updated settings interface, but the output options that are ON are the same as the default options when you start new simulator and so are size of the frames and the "Estimated Time" the simulation would take.
Example+Scenes:

I switched all output options, except liquid, foam and splash velocities. file size went down quite a bit:
but they are still way larger than in the the one form 03-17-2016 (see below) and the time estimated is about double the time it took to simulate the last one.
Is this the best we can squeeze from the current engine or are there other tweaks we could employ, so we can get a new simulation as fast and tidy as the 03-17 one? perhaps OFF other options that are not particularly relevant to this sort of simulation?
Thanks a lot for the tip. "You can turn off.....IDs if you are not going to have slow motion effects" makes so much more sense (to me) than "...Use it when render time size variation is needed, or when frame blending will be involved (animated frame index or non-integer play speed)".
The docs don't mention the Output Particles / Size. Do we need this option ON and what for?

cheers and thx in advance for the help

[Svetlin.Nikolov]

Hey,

I guess the file sizes could still be big because of the velocities - they are one of the biggest channels Phoenix writes to the cache files. We could do a ton of speed improvements on our side and I hope these would make it into the nightlies or for 3.1, but for now you could generally speed up Phoenix liquids by decreasing the Steps per Frame, reducing foam or splash production, and turning off B2B for the Foam or Liquid-like for the Splash and the liquid Viscosity. Note that back in March the solver was still in deep beta and there were still many issues, so setups that might have looked good were not necessarily acting properly and did not allow changes to many parameters.

Render time size variation is an option in the Particle Shader. Frame blending is what occurs when you make changes to the Time Bend options in the Input panel - for a frame on the timeline you need to blend between two caches instead of showing an exact one. The Size is missing from the docs for some reason, will add it, but it's pretty straightforward - you need it when rendering the bubbles, so that you'd have the proper sizes of the spheres and you'd be able to visualize the way they have interacted during simulation. Will update the docs with links to those, thanks for pointing these out!

Cheers!

[baro]

Hi Svetlin,

thanks for adding the Outpu/Size to the docs. Can I ask you to please give an example how to use it to improve renderings?
Here is what I hope it can help me with.
-Started a new simulation mimicking the settings form the example ship scene.
-sell size similar to the example (even smaller)

-foam size same as the example

-foam came up with bigger than expected balls (foam white, splash red)

-how can I use the output/size to fix up rendering/animation without rerunning simulation?

If I have to rerun simulation what settings would you advise me to use?
should I decrease the sell size below 10 cm?
if I keep the same sell size what size should the foam be?
is there a direct relations between the two?
how about the splash size? recommended cell/splash size ratio?
I realize it is useless to try to make analogy between CFD's and FLIP principles, but there must be some rule of thumb guidance.
once I was told on this blog that with time I will get the hang of those settings, but after so many moths of hit and miss I am not even close to figuring this out.
any help, sharing experience, hint on the matter will be appreciated.

cheers
pl

[Svetlin.Nikolov]

Hey,

Sorry for the late reply - you can adjust the bubble sizes from the Particle Shader (PHXFoam) without touching the original sim - there is a multiplier there and also additional size-altering options you can use to add even more variation, etc. Also, if you need to simulate again, you can use Resimulation to run only the particle systems (foam, splash, wetmap) you want to fix without changing the rest of the simulation - just alter the foam or splash settings and check just the systems you want to change in the Resimulation panel and then run the sim again - it will skip all the other operations and will finish faster than a regular simulation.

The foam size, unlike the splash size, can be directly controlled from the Foam panel, and it is not related to the grid resolution.

Can't really give you a rule of thumb about the splash size though. You'll have to experiment with this a bit to get a feel for the proper values. Btw, doesn't the Ocean preset work well for your scene? There's been some changes to it after the release of 3.0, so you better ask for nightly access to the 3.0 nightlies so you'll be up-to-date.

Hope this helps, cheers!

[baro]

Hi Svetlin,

tested the preset with "3.05.01 Nightly Build ID: 1611167061".
started with a clean scene, selected a 30x10x1.5m boat. the preset suggested this grid:



the results were expected coarse water simulation (cell size 0.3m) and pretty large foam/splash baubles.


I don't know if this can be considered that the presets work well, but that is not the point of this post. The presets are a good starting point from where I kept modifying the grid resolution, foam and splash parameters until I got them to decent looking, but the problem is I cant get rid of some very large balls among otherwise finer foam. I tried with distribution varying form 10 to 10000 (foam size 0.05m) and always got these giant spheres:

is there a way to suppress generation of such big foam baubles?
cheers
pl

[Paul Oblomov]

If I remember correctly, splash size computes automatically, it depends on cell size. So, if ya have coarse grid - then splashes would be huuuge. Try to shrink their size via shader.

[Svetlin.Nikolov]

Yup, and the Quick Setups are intentionally down on resolution, so people would be able to run them with the Demo Phoenix as well, because it has a restriction on the voxel count for sim and the particle count for render. If you increase the grid resolution, the splashes would become finer, but the foam will not be affected. You would need to turn down the Up Variation of the simulated Foam in order to get more uniform sizes, if you want to do this at sim time and not at render time. Otherwise, you would also be able to cut off bigger foam bubbles using the Particle Shader (PHXFoam) Size Limit.

Hope this helps Cheers!