Low-res from hi-res?

[3dwolf]

I simulated a simple temperature-only smoke with some max-wind(turbulence) which looks quite ok in my opinion, it is just too fast (like 4x) and too high-res to use like 50 copies of it in the same scene. Most of the visible part ist between 310° and 350°. Used an limited adaptive grid 310° + 40 cells. Output: Temp + Velocity
(as something messed up the license right now (request should be soon on its way, as our lic-guy told me) I cannot test right now)
Frame-blending and velocity-based retiming both do not look smooth in motion and velo-based is ram-expensive with like 12GB+ (but looks a tiny little bit better).

Some more or less stupid questions:
Resim can only increase resolution?
Resim does not care about adaptivity if the base-simulation shrinks and just cuts down?!
Resim with a modified timescale didn't work as I hoped.
Does "timescale" also rescale the max-wind?
When I tried timescale (some time ago) the new simulation looked very very different than with timescale=1.
I tried to put a second low-res-grid in/over the high-res-sim to somehow cascade it over there but didn't succeed. I guess my souce-settings were all totally wrong.

What would be the way to go if you want to reduce the resolution of an existing simulation and what ist the best way slow a simulation down? (for someone who uses Phoenix not as often as it deserves)

[Svetlin.Nikolov]

Hello! You've hit the nail right on the head We're limited on tools to properly slow the simulation down - as you have seen, both input blend modes are unsatisfying in many cases. Tweaking the timescale will generally just slow the simulation down, but getting a similar shape is next to impossible, as butterfly effects prevail in the simulation.

You asked for this in the exact moment we were looking to improve the situation by giving the resimulation a re-timing ability as well. This should make its way into the nightly builds in several days and we'll get back to you.

About decreasing resolution with resimulation - it's just something we never thought anyone would want We'll see if this can make it into the nightly builds as well.

I've got to check how timescale interacts with max forces and is there an issue with shrinking grid resim in order to answer properly. Same goes for overlapping cascade grids.

[3dwolf]

Thank you for the reply. As our lic is back to work I'll play some more and start low 'n' slow now

Kind regards
Wolf

PS I loved instances for e.g. static clusters of clouds in the sky. Made tweaking of the masses a little easier.
PPS Is there a general interest for a PHX-Read-Object that only contains Input-, Preview- and Rendering-Settings but has no Simulation-stuff?

[Ivaylo Katev]

if you have a hires simulation that renders too slow, you can just increase the render step, it's almost equal to low res rendering, except the bigger ram usage.

[Svetlin.Nikolov]

The resolution reduction is a very easy tweak and will be in for Tuesday's nightly build. I hope by then there will be something in for retiming as well

PPS Is there a general interest for a PHX-Read-Object that only contains Input-, Preview- and Rendering-Settings but has no Simulation-stuff?

The latest V-Ray for maya has the Volume Grid: http://docs.chaosgroup.com/display/V...VRayVolumeGrid. It essentially is Phoenix with no sim - I think exactly what you are asking for. It is scheduled for the max version of VRay as well soon, but can't say anything more concrete.

[3dwolf]

if you have a hires simulation that renders too slow, you can just increase the render step, it's almost equal to low res rendering, except the bigger ram usage.

Thanks, done that before, works great for a few copies.

The resolution reduction is a very easy tweak and will be in for Tuesday's nightly build. I hope by then there will be something in for retiming as well

Good news

The latest V-Ray for maya has the Volume Grid: http://docs.chaosgroup.com/display/V...VRayVolumeGrid. It essentially is Phoenix with no sim - I think exactly what you are asking for. It is scheduled for the max version of VRay as well soon, but can't say anything more concrete.

Ah, yes! I'll wait.

[Svetlin.Nikolov]

Alrighty, the nightly builds are out (in the folder for Oct 21st) with the reduce resolution option. We got the retiming working on a basic level, but it still needs at least a couple of days more work. Will keep you updated.

[Svetlin.Nikolov]

Hello! After a long while, we're got the 'Re-time' function in the nightly builds. It still has some rough edges to smooth out, but you may try it and see how it works out for you

Here's some more info on that:

http://docs.chaosgroup.com/display/P...time-scale,etc

http://docs.chaosgroup.com/display/P...ndResimulation