View Full Version : Rendering wispy smoke with PF Krakatoa

02 February 2009, 03:48 AM
Hi guys,

I'm trying to get the look of wispy smoke in PF. Here's a test render , just a PF source with wind and turbulence and a drag.
I've tried rendering with facing maps with opacity and smoke/ noise texture. Perhaps I've done it wrongly but i seems to be losing the details of the smoke.
With millions of small cube and motion blur,I get the details but small dots are visible which makes the smoke looks grainy especially at areas where there are less particles (see smoke 02.jpg). I tried the same thing on Krakatoa and get a better effect but the tiny dots are still around. I read somewhere that i should blur the smoke in post but blurring it will lose the smoke details.
Is there anyway to get the wispy smoke look with details in PF , Krakatoa or after effects?
Thanks in advance for any reply.

02 February 2009, 03:56 AM
Krakatoa 101: If you are seeing individual points, your density is too high or your particle count is too low (or both). Play with the Density Exponent - go down to -2, -3 until the single particles disappear and you get a smooth cloud. If you don't have enough particles (for what you are doing, 10 millions should be the bare minimum), create more partitions.

IMHO, this is one of the main mistakes most people make when rendering in Krakatoa. In most cases, rendering 10M particles takes 10 to 20 seconds, so just add more and make them barely visible as individual points to get the smooth look you are after. In fact, the same applies to facing particles - your opacity should be so low a single particle shouldn't be visible to the eye, it is the accumulation of the many low opacities that you want.

Also remember that Krakatoa renders TrueColor data - save as EXR and then increase the Gain or Gamma in post to make it brighter if the initial version is too dark, but never allow particles to appear as dots.

02 February 2009, 03:25 AM
Thanks for the great advise bobo :scream:
It's looking much better now. Here's a test render with 10 mill particles. Will have to add more partitions to make it look even smoother especially in areas with less particles.

CGTalk Moderation
02 February 2009, 03:25 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.