Compensate DOP Scale Time

[Wats]

Hello,

Is there a way to slow down DOP particle simulation without changing liquid behavior too drastically?

I made a liquid simulation with popfluid it looks exactly like I need but I need to slow it down to make it look like it was shot on Phantom camera (think of one of those fancy table tops from Marmalade as a reference:). 

I use standard 24 FPS and Time Scale on DOP is 1 substeps = 1, time scales on popfluid and popsolver inside DOP are 1 as well substeps on popsolver 1, 2. So to slow everything down I tried to half Time Scale on DOP but liquid behavior changed completely, when I try to do the same with time scales on solvers inside same thing is happening. So the question is is it possible to preserve liquid motion after changing time scale? Maybe unlock solvers, dive inside and change something there? 

Thanks.

PS. i know that retime is other option probably most obvious, but unfortunately it doesn't look the way I need especially with collisions.

 

[Diego A Grimaldi]

You can use the timescale on the Flip Solver for that!

 

[anim]

it's tricky as not all microsolvers correctly respect timescale

especially most solvers using any sort of noises like POP Force, POP wind, Gas Turbulence, ... they all use global time instead of simulation time for their phase and even if they used simulation time that would only work with DOP net level timscale

then also your sources and colliders have to be compensated but their velocity kept in seconds

there may be other things as setups tend to have a lot of variables

[Roznick]

You might want to look into this tutorial by Simon Fiedler

https://vimeo.com/251487780

[Wats]

On 3/9/2020 at 10:05 PM, anim said:

it's tricky as not all microsolvers correctly respect timescale

especially most solvers using any sort of noises like POP Force, POP wind, Gas Turbulence, ... they all use global time instead of simulation time for their phase and even if they used simulation time that would only work with DOP net level timscale

then also your sources and colliders have to be compensated but their velocity kept in seconds

there may be other things as setups tend to have a lot of variables

Thank you for you reply, I kinda got the idea but can you please elaborate a little on this part "then also your sources and colliders have to be compensated but their velocity kept in seconds" ? Just to get more info in what direction to dig to achieve the effect. I'm still new in Houdini and everything feels very complicated and messed up especially after Realflow. Thanks!

On 3/9/2020 at 9:59 PM, Diego A Grimaldi said:

You can use the timescale on the Flip Solver for that!

 

Unfortunately it's pop fluid simulation so there is no Flip solver.

 

On 3/10/2020 at 5:47 AM, Roznick said:

You might want to look into this tutorial by Simon Fiedler

https://vimeo.com/251487780

Yep I saw this tutorial, unfortunately its based on retime I think you can achieve same effect with Retime node, but my goal is to slow it down without retiming but actually simulate in "slow motion" (more FPS).

Thanks.