Hello again ladies and gents! I’m back after a long time.
I’m messing doing a little animation: a rigged car doing it’s stuff with dust/smoke coming out of it’s wheels, and a fairly complex background. But each time I adjust or tweak a parameter in the smoke sim, the render then takes a looong time. I was wondering… would compositing help me speed things up? I am guessing that just rendering the smoke simulation every time I tweak it would be faster that rendering it all over and over. Am I right? Can it be easily done? How about the shadow the smoke casts on the scene and other objects?
It will help… some.
Rendering smoke generally takes forever, especially when it comes to animation.
On the other hand, if your animation and camera motion is set, render that separately.
You can easily composite the smoke back in afterwards if the smoke renderlayer is masked by the solid geometry.
Rendering the smoke in its own render-layer/pass also has a number of other benefits.
For example, you can set different (more aggressive) denoise options for just the smoke!
A cheap-but-very-effective way to make “better smoke” is to superimpose the stuff upon itself, offsetting each strip slightly in time. (I’ve also seen people slightly tweak the speed of some of the strips, and to selectively blur them.) This gives you a denser, more chaotic smoke effect with no additional computational effort. The same thing can be done with fire.