When decrease time scale, fire lose details

[hammerbchen]

Hi,

I just did a slow motion fire by reducing time scale, but I lose details of my fire when doing so.
https://www.youtube.com/watch?v=MMxWlNXQMug

Any suggestions to compensate this problem?
(This was done by using PhoenixFD 2.2)

best,


Chen

[Svetlin.Nikolov]

Hey,

Indeed - this is the same as using high SPF - the simulator moves the fluid in shorter steps and the details get blurred out.

The proper alternative is to use Resimulation with Time Bend enabled:

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

Cheers!

PS: The sim looks very nice

[Ivaylo Katev]

if you have spf higher than 1, you can decrease it with the same coefficient that is used for the time scale, this will keep the details

[hammerbchen]

if you have spf higher than 1, you can decrease it with the same coefficient that is used for the time scale, this will keep the details

Hi Ivaylo, I did check last night. But when I see the animation curve, there are actually two parameters for SPF, one is maximal SPF and the other minimal. Which one should I adjust accordingly?

[hammerbchen]

Hey,

Indeed - this is the same as using high SPF - the simulator moves the fluid in shorter steps and the details get blurred out.

The proper alternative is to use Resimulation with Time Bend enabled:

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

Cheers!

PS: The sim looks very nice

Hi Svetlin, I did try Resimulation, but I have problem with it. Since my fire src is based on PF, I found PhoenixFD 2.2 is not working when resim with fire (is okay for smoke), when doing resim, fire seems to disconnected. I will make a screenshot later..

tks much! Good job from you developers

[Svetlin.Nikolov]

Hmmm, do you have a scene with your PF setup? We have to clear such issues.

[Ivaylo Katev]

Hi Ivaylo, I did check last night. But when I see the animation curve, there are actually two parameters for SPF, one is maximal SPF and the other minimal. Which one should I adjust accordingly?

yes, in the past we used auto spf adjustment, this is remaining form this old concept. the actual parameter is called only spf, but i'm not sure that it can be animated anymore. perhaps the solution suggested from svetlin is the best one, to resimulate with slow down. in this case the velocity is already calculated with constant spf and the detail remains the same, nevertheless the resimulation can still decrease the details, must try it and see

[Svetlin.Nikolov]

Ivaylo, the time-bend resimulation has two modes - one that may decrease the detail, and another one that will not. Please check the help site - I've linked it above.

The steps per frame are already an integer value so one should not animate them or the simulation will most likely change behavior drastically on each step.

In this particular simulation we can't talk about decreasing the steps per frame, because they are already at 1-2.

The PF setup should be made to work with time-bend resim as well.

[hammerbchen]

Hi Svetlin, may I have your email so I can send my scene file to you. Or there is any other way?

[Svetlin.Nikolov]

Hey,

We usually route the scene files through support to keep better track of what is done or left to do - please send it to them and mention the forum thread.

Thanks!