Different Ways to generate smoke

[michal]

Hi,

I'm studying smoke these days and found it's not so easy as I thought. I searched odforce forum and Houdini examples, and I noticed that there are 2 ways to generate smoke in Houdini.(maybe other ways I don't know?)

1. Particle simulation and then render particles as sprite. I learned this from Miguel's tutorial. This seems intuitive for me because I always imagine smoke as tiny particles.

2. Smoke dynamic simulation + Volumetric rendering. Create some volume primitive and then render it with volume shader (i3d shaders were also discussed in some posts before). It's not bad but it seems lots of additional work than the 1st method: create the smoke container, define the volume primitive, etc.

The worst thing for me in the 2nd method is that I can't control the smoke as easily as the 1st way. In particle simulation, I can use particle birth rate to control the density and use forces to control its movement. But in the 2nd way, although density can also be adjusted, the simulation speed will be terribly slowed down if we increase it too much. The movement is also not easy to be controlled in the 2nd way. For now I haven't figure out how to create smoke rising from a cigrette in smoke dynamics.

So, what's your preference about creating smokes? What's your opinion in different ways?

Thanks.

[Symbolic]

Yeah... I am also interested in this topic... and has always been a puzzle.

I guess i3d and iso-surface is also a standalone technique to create smoke.

I will be very happy to hear about workflow and techniques...

Cheers.

[Guest Swann]

One of more interesting techniques these days is to turnOff fan and/or put off cooler from your CPU. On my eye it gives quite realistic results. :nuke:

Of course like with everything, more complicated stuff/model you are making the more dramatic effects it gives.

Remember that air temperature also has a lot to do with how fast you see the effect.

Edited April 29, 2008 by SWANN

[kleer001]

3. Particle simulation that renders into an i3d volume

For a still I think the most important thing for beleivable smoke is good shadows. In motion it's irregular clumping (a.k.a. no cotton balls or spheres)