Smoke Simulation Help?

Hi everyone, I have been working hard the past few days trying to get a good handle on Smoke Simulations… I know that volume rendering is always a heavy load for gpu’s and cpu’s, but what kind of times should i really be expecting?.. because i feel it is actually taking far too long on my machine. And i am wondering if i have some setting set improperly, or it really cannot be done faster on my system… (Ryzen1800x/Nvidia GTX1080)…

For example… Rendering out 150 frames to a sequence of .png’s at a resolution of 1920x1080 is taking well over 2 hours… Closer to 3… As i am attempting to achieve high detail and high quality, the Smoke settings are rather high and i’m trying to keep my samples at 400 to get rid of most of the noise… I have pretty much dropped every setting i can as low as i can to maintain a decent smoke quality and try to optimize the render time, but i think im at a loss… Its really starting to hurt my head, and im starting to feel like i might have to give up… it just doesn’t seem like it should be taking this long… and i intended to render these out at 4k anyway… Is everyone else’s performance experience similar? or do you think i have something buggered up?.. any suggestions will be taken with a great amount of appreciation…

Thanks

Sorry… Forgot to mention im using 2.78c…

My opinion, and I don’t have much experience with smoke in animations, is that your render times are actually fairly fast. The only thing I could suggest (and you may already have tried this) is reducing the size of your smoke domain and/or using adaptive domain. Maybe someone else will have a better solution. Good luck!

Thanks for the suggestions… I set the domain size right to extent of the camera and tried to minimize it as best as i could… and as for the adaptive domain, i initially used it on my first test run, but found that it was creating an abnormality in the final render… some of the frames didnt seem to scale correctly… so i disabled it… I might be wrong, but i think the adaptive domain only affects the the initial bake of the smoke simulation and not really the rendering aspect… but i would love to be terribly mistaken… I honestly do hope i have missed some setting or someone has a good trick for me… or even i need to go grab a particular video card!!!.. because at 2 and half hours to get 6sec of 1080p magic,… 4k is going to be absurd…


Made a quick test scene to see if adaptive domain (which is on in the screenshot) made any difference in render times. For this scene with adaptive domain off it took 5:54.63 to render and with adaptive domain on it took only 3:36.82. Do you have one big smoke emitter or a bunch of small ones that are in the same domain but don’t really interact with each other?

wow… you are absolutely correct!!.. I just tested it myself and it cut the render time in half… but then I am having another problem with the adaptive domain not scaling correctly throughout the animation creating a sort of flickering effect in the final render… as if the resolution of the smoke is inconsistent through the baking process and it sort of jumps shape in a few frames of the rendered out sequence.

Hmmm… I’ve never experienced that before. I tried messing around in blender in a futile attempt to recreate it and Google wasn’t much help either. Does it appear in the viewport or only once rendered? How high is the resolution of your domain? Do you get “jitter” on all adaptive domains you’ve tried or just this one?

Check out this video i just posted… it will give you an idea of the flickering problem im having with the smoke sim… keep an eye on the shadow areas to see it clearly… sorry its so short and abrupt… https://youtu.be/vavqm7sSMCU

Very cool! Do you have a blend file or screenshot of your smoke domain settings I could look at?

I’ll try to post one up this evening… I’m off to a meeting for a little bit… Thank you so much for stickin with me on this!!.. it is driving me crazy!!!

So… im not sure how to post a blend file… but here are a couple pics of the domain settings and flow settings…



I have not baked this one yet, but these are pretty much the settings im trying to work with for the smoke detail and density.

I also watched a tutorial on making an ink droplet type of render, and it mentioned briefly that there could be some complication when rendering higher resolution smoke and using Adaptive Domain and Smoke High Resolution functions… he didnt go into detail, but i am wondering if that may be the flickering issue that i am experiencing.

Sorry for the delay… Here is the youtube link to my attempt at the smoke simulation. I baked it at the same resolution you had, however, I don’t see any flickering, but maybe you can.

Not sure what else to suggest, maybe try decreasing the density of the volume scatter shader, increasing the resolution of the sim, starting from scratch with a new scene or maybe even reinstalling blender. If you can’t get it to work I can take a look at the blend file if you can get it to me (I don’t know how to send them either, maybe PM or dropbox).

No problem!!.. thanks for the help!.. Your sim looks perfect without the flicker… the density in my blend is set extremely high via the math node, but i hope i dont have to change that… i kind of need it reeeaaaally dense… I have re-made the scene at least ten times with no difference in the flicker, and reinstalled blender, so… im thinkin i need to change something else… i’ll try a few more tests and see if i can figure out how to upload the .blend… Thanks again!!!

Quick update… I uninstalled Blender again, and completely wiped it from the registry as well… I then re installed it via the .zip method rather than the windows installer… I dont know if this is the reason, but i am seeing a tremendous increase in performance in all of Blender… I have not yet rendered out another smoke sim but that is next on the list…

also,… for whatever reason, the smoke renders faster the more i increase the density now… as if it is actually calculating less…any way… back to it…

So I have found something that may be relative to the problem, and i am ashamed of myself for not checking… i am definitely at fault here… when I did my bakes and renders, i overlooked the default setting of 24p for the framerate… Obviously, that looks terrible when imported into a 29.97 sequence in Premiere,… and finally even, worse exported to 23.976… flicker city… i am an idiot… on a side note, the render does still flicker, but far less than before… I think i might be a little too ambitious with my node values making this a difficult material to render… but im gonna keep tryin to get it silky smooth and finally render one out at 4k for a project of mine… Thank you so much for your help @davidkollmar… You sent me to all the right places… kept me motivated, and I indirectly got my system running a helluva lot faster than it was thanks to your suggestions… Thanks again. here’s a small clip of the better smoke… way less flickering… unfortunately pretty low res test…
https://youtu.be/pJEIqfOslFI

No problem at all. Happy to help! When you get the 4K sim done I’d love to see it.
Happy Blending!