fume FX beginner, c4d r21 redshift, latest FumeFX

[thomastraum]

I am learning fume fx at the moment


Just like any new tool I am trying to get up to speed quickly by finding the few really important things about the tool.
I learned a lot in the last two days but here are some questions I have which I don't understand and I feel its best to ask for help
I followed this tutorial https://www.youtube.com/watch?v=vGjLVVcjFKs and try to port it to c4d r21, then used it as a basic tut to explore.

For now, it looks nothing like the original but I also started tweaking parameters to learn.

here is my file:
https://www.dropbox.com/t/Ybklgmz0yxphs5DO

My main questions

1) how do I limit calculation times going towards infinite. this is the biggest problem as I can't really cache the simulation, it gets longer and longer per frame.

I am aware of max iterations and limited to 100.
Whichever spacing I choose the calculation never finishes on a longer frame range.
step size 0.3 about 40 frames in it get super slow
step size 0.7 about 100 or so frames it get super slow

I must be missing something!


2)

https://www.dropbox.com/s/gydyj1mly1frz ... 7.png?dl=0

How do you render it without being blocky in redshift? I am aware this is more of a redshift question but I am hoping someone could help here who uses redshift. I played with all settings in the shader. I am asking here because I haven't had the same problem when I used other smoke effect software using the same shader.

[thomastraum]

just checking the date on the other posts I realized this forum is kind of dead. Where is a good place to ask these days?

[sitnisati]

Hello,

1) how do I limit calculation times going towards infinite. this is the biggest problem as I can't really cache the simulation, it gets longer and longer per frame.

You can set the grid spacing to 1.0 for a start. Fluid dynamics with lots of details takes time to compute and we usually leave it overnight for something highly detailed (like 32Gb or memory sims) on our dual Xeon machines. So, for a starts you pick a grid that's the most up to 250x250x250 or something around those values.

2)

https://www.dropbox.com/s/gydyj1mly1frz ... 7.png?dl=0

How do you render it without being blocky in redshift? I am aware this is more of a redshift question but I am hoping someone could help here who uses redshift. I played with all settings in the shader. I am asking here because I haven't had the same problem when I used other smoke effect software using the same shader.

This is blocky as the smoke is very dense near the torus and you'd have to push it a bit further away by using the object source normal velocity.

Regards,
Kresimir Tkalcec

[thomastraum]

Amazing thanks so much, this really helps.

I'll iterate over my setup and report back.
I have some beefy machines too but, I'll try again.

I assumed the fluids calculations should becomes stable after a while since they dissipate so at some point I would expect the simulation to take a fixed time per frame eventually, my experience so far has been that however that it keeps increasing even after 100 frames in. I was thus wondering wether I got something wrong in my scene.

[sitnisati]

Hello,

You're welcome!
I've simmed few dozen frames with grid spacing of 0.7 and have changed the Normal Velocity on Object Source to 10 and the result (frame 11) is attached.
With Normal velocity on Object Source you will get more smoke thickness around the geometry (as normal velocity pushes the smoke away from the object).

Simulation time will rise as long as the grid expands - you can make the grid stick closed to your actualy simulation area, but keep in mind that grid also has to be big enough to allow velocity field to develop properly to create natural motion. It's always a tradeoff.

Looking forward to see your next iteration!

Regards,
Kresimir Tkalcec

[thomastraum]

Hi Kresimir,

thanks so much, this really helped. A hint from you saves me days on my side.
here is the latest result. https://vimeo.com/trauminc/review/464992871/afd85339e9
this is set to 0.5 in spacing. let me know if you have any feedback or other tricks for this scene.

next challenge coming up!


Best,
Thomas

ps shame we can't attach files this could be helpful. You could start a content repository as they do on the x-particles site.

[sitnisati]

Hello,

Thanks for sharing - it looks much better now!
Now you might play a bit more with the shader and emissivity to get a more dramatic look.

Best,
Kresimir Tkalcec