Resimulation workflow (PhoenixFD 3)

[hammerbchen]

Hi,

I am reading this page for slowing down my smoke:
https://docs.chaosgroup.com/display/...-TimeBendResim

There is one thing I am not complete understand. Imagine a scenario like this:
1. Run a base sim for a smoke
2. Run a resiumation from the base sim, at the same time I Amp.resolution by 1, and slow down by smoke by using "Time bend controls" and set Input/ play speed = 0.5
3. After step 2, I realized the speed of my smoke is still too fast. I want to make it even slower

So, I already amp grid resolution by 1. If I want to change the speed of my smoke by resimulation, will PHX calculate the amp resolution again?

The reason I ask this is that in FumFX you have three separated caches ( base sim, wavelet sim, and post sim (for slow down)). If you don't like the speed of post sim, you can run the post sim at any time without redoing the wavelet sim. I hope you understand my question, thanks for your time.

Rgds,


Chen

[Svetlin.Nikolov]

Hey Hammer Chen,

If you don't change the paths in the Resimulation panel since the first time you resimulated, it will overwrite your first resimulation. You could manually point the resimulation input to the previous resimulation output and resimulate over an already resimulated and amped sequence, but in this case there is no need to do it - just change the play speed and run resim again

Cheers!

[hammerbchen]

Hi Svetlin,

Tks, I have few more to clear out my head, correct me if I am wrong:
1)PHX 3 can slow down smoke even without exporting velocity channel. By changing In output/ play speed (Frm interpolate), make it less than 1 (i.e., 0.6), PHX will read the base sim cache and render out smoke in slow motion ON THE FLY.

2)But if you run Resimulation, this will actually "collapse" the interpolated caches from base sim caches. So compare with 1), the render results is basically the same, only difference is it take less time to render each frame since the caches are already interpolated ( resimulation caches)

3)The quality is much better when exporting velocity channel for slowing down the smoke. Same as 1) and 2). Once can slow down the smoke without check "Enable grid resimulation." The slow-down version of smoke can be slow down ON THE FLY during rendering.

4)But if I run Resimulation, it writes out caches based on velocity info from base sim caches. The results are much accurate and can render faster.

5)unlike fumfx which have distinct cache file naming from beginning. Base cache, wavelet cache and post cache. For PhoenixFD, it mixes the last two. wavelet caches share with post effect (slowing down). So when you are doing resimulation with PhoenixFD, you need to manually set file path/naming to avoid unwanted cache overwrite.

Regards

Chen

[Svetlin.Nikolov]

Hey,

That's correct - if you need wavelet and retiming as separate steps, you should separate these manually - by default they are done simultaneously. The resimulation workflow still needs some streamlining in my opinion, I hope we can work on it more for the next minor versions.

Cheers!