Normal render times for fire/smoke?


I’m trying to render a short sequence with fire and smoke. I’m using these settings;

to create a flame this large

Having to render on CPU as GPU is not supported for rendering Fire and Smoke, using an i7 4770K @3.8 GHz and 16GB ram. To render a single frame at around 560 AA samples (total) is taking upwards of 5 hours. Is this normal? Are there any ways of reducing render times other than smaller dimensions/less samples/less light bounces (tried these, little to no effect or results not good enough). Thanks in advance for your help,

Dan, First of all , always use physical disk cache, not ram. Go to your Smoke Cache Tab, and Give some name to add Smoke Cache File (Extra overhead is that you need to delete the directory, once you are done with animation, to recliam the disk space).

Your smoke density settings are off too. I suggest using the “Quick Effect” first to familiarize yourself with Smoke Simulation.

Then Bake all Dynamics (Just press bake all Dynamics button, which is in smoke cache tab).

After all the above, comes the Rendering/Compositing part. Which if you use the above method, wont be that much long.

5 Hours is way to much.

Another good trick for producing “big, phat,” fire-and-smoke “on the cheap” :slight_smile: is to render some of it … doing fire and smoke separately … then overlay both the fire and the smoke with several copies of themselves, offset by time, even speed and so-forth. Ue slightly different alpha factors for each. Apply slightly different tints and levels of brightness. Apply slight blur or defocus to some.

Fairly instantly, you are rewarded with a much more complex and visually-rich effect, but without having spent more time on simulation, and having used fairly small simulations each time.

Of course, the campfire doesn’t actually produce light. That’s done with separate lighting, which is also animated so as to “flicker.” The lights probably don’t need to cast shadows.