Fire and Coals material study

I have been working on rendering good looking fire like you might find inside a forge or furnace. Here are some references.

From my study so far it appears there are many many variations on fire depending on the temperature, the material and the camera exposure level.

The type of fire and coals I’m trying to create have these similarities:

-Much of the fire is made of coals. Not much of it is flame.
-The coals are black or dark near the outside or cool part of the fire.
-The coals are progressively red, orange, yellow and white as they get closer to other coals.
-The overall lighting is a warm orange glow on a dark or black background
-Turbulence and warping are visible from hot air lensing

I haven’t addressed the lensing yet - I plan to do that in animation. I’m trying to capture the rest of the elements in a blender scene. Here’s where I’ve gotten so far. I can see that it needs to be hotter and more lively. That’s what I’m working on now.

I hope to better my fire material study through community advice and to share what I’ve already learned about creating good looking fire.

I am fascinated by glowing coals and have often studied them in an attempt to recreate them myself.

I think you are off to a nice start, but they look a little dark and or not very hot. Glowing coals emit more light in hotter colors of red going to white.

the first one looks quite realistic, the others are too dark/ orange

Actually I think the first three are reference photos and the last is the attempt of creating that in blender.
I agree with dreamsgate you have to increase the temperature more.
But you are definetly on the right track.

Ok, this one’s a little hotter and livelier.

This one is close enough to see the detail on the coals too. It’s not a social commentary or any such nonsense, it was just better than using spheres or cubes because of the extra geometry.

Getting closer. Try turning the heat up a little more, although that might make it lose the dark patches on the edges.

The coals looks weird more like fish or frog eggs then coals. Maybe it’s the specularity or the translucency. Are you using sss on the coal?

No, there’s no SSS on the coals. I think I see what you mean about eggs. They have dark spots on them. That is actually because I mass copied the Suzanne monkey head to get interesting coal shapes and the mouth part is “cooler” than most of the coal. I’ll explain…

The way I’m approaching the coals is to use ambient occlusion. The coals are hotter and therefore brighter near other coals. So I calculate ambient occlusion and invert the result. Then I pass the that value through a color curve to adjust from dark red up through bright yellow.

If you examine the suzanne model, you’ll see that the mouth and lower face aren’t occluded much. So they would be bright in the AO pass, which would be dark after being inverted. That’s why the “egg” spots show up. I’m working on a properly modeled scene that should show off the ember glow a little better.