Smoke sim: difference between "heavy" and "light" compression?

I’m currently doing a smoke sim for an explosion. Final animation is in HD, otherwise I’d be done by now! :spin: I have the domain res at 64, and the high res divisions at 5, and it STILL looks a bit too blurry.

Now normally I’d just bump it up to 7 without a second thought… well one problem. At 5 divisions, the cache takes up 80 GIGABYTES!!! YIKES!! But I DO have the compression set to “light”.

My question is, just HOW effective IS the heavy compression? Time isn’t really an issue here.

Also, I assume light vs. heavy wouldn’t change the results themselves, just how they’re stored… right? “Heavy” compression isn’t going to degrade the quality is it?

The quality stays the same. Heavy uses more processing power but less cache size. In the past, heavy was a little error-prone (exploding smoke). Don’t know if that is gone by now…

About how much of a difference in cache size does it make? I understand that it’s probably not a constant value, but is it worth it? The whole domain doesn’t fill up with smoke, there’s a lot of empty air (but like in the corners where I can’t just reduce domain cube’s size to optimize)

Hmm, didn’t use it for a while due to the instability. Don’t know how much differnce it does make. But maybe you wanna try it out?

642^5 divisions with light compression gets me a total cache size of 80GB.
2^7 divisions with heavy compression gets me a total cache size of 120 GB.

Haven’t noticed any problems with heavy compression. Not too shabby!

Rendering the explosion right now, ~9 minutes per frame, 1920x1080. Looks pretty photoreal, just wish it had more of that wavelet “whispiness” to it, looks somewhat blurry now. Not sure why… except that maybe the camera is a bit too close to it (but it’s a matchmoved shot, so whaddaya gonna do?). I’m enhancing it in AfterEffects afterwards (turbulent noise w/ colorama fire gradient applied on top of bright areas, tracked to match camera shake).

Geesh, seems like I need to bump into heavy compression once again :slight_smile:

Would you mind sharing you visual results? Maybe a change in Wavelet noise size can give you the desired “whispiness”…

Yea what exactly does “size” mean with the wavelet options? I’m pretty happy with the results now, but more whispiness would be nice. Perhaps it IS just the domain res isn’t high enough… Oh well.

Here’s a pic:

Say I wanted to have the wavelet noise sharpen that up a bit. How should I change the “wavelet strength” setting? It’s at 2 right now. Maybe bump it up to 3? Normally I’d just go an do it, see how it goes, but this thing took at least a day to bake… I don’t really want to let go of it real fast.

“Size”? My Blender 2.55 has “Resolution” and “Strength”.

Resolution: This defines how much things are sharpened up by the wavelets - increasing this will make things take longer but by far not as longer as upping the domain res would.

Strenght: This is the strengh of the wavelet noise - increasing this will add more turbulence.

In your case I guess you should try to increase the Resolution by one division…

Could it also be that I need to increase the volume material’s “step size”? I think it was at 0.100