Faking radiosity with color ramps and empties

Greetings everybody,

I was trying out some technique used in other apps to fake radiosity, and this is what I came up with:


You basically place the color bleed on other materials by using a color ramp mapped to an empty.

Here is a great tutorial for LW: http://www.3dtutorials.sk/index.php?id=13

And here is my .blend: http://www.primatestudios.com/temp/faked_radiosity.blend

I would have uploaded a video but it might even be faster for your to render the animation quickly from the .blend than waiting for the video to download.

Matt :slight_smile:

This is totally kick-ass - so clever, so quick with excellent, controllable results. Just shows how powerful ramps are.

I’m gonna have a good look at that LW tutorial but I think someone should make one which is Blender specific. This is a wonderfully quick GI fake - my only critisism of the given .blend scene is that the effect is a little too strong. Then again, that can be adjusted.

That has to be one of the coolest techniques I have ever seen in CG. With the new render engine rewrite and the node-based materials, I think this is going to be a very workable method for Blender. I must say I am pretty excited - the smoothness of raytraced GI, as fast as radiosity and much more controllable than either.

And you were right about it being quicker to render than to download. I wouldn’t want to try the same thing using yafray GI. :slight_smile:


I’m amazed that no one is responding to this post. Perhaps everyone else knew about this trick but I certainly had never thought of it. I still think it rocks.

My only question is that there seems to be some post-processing going on (glow or something). I’ll take an even closer look at the .blend later.


looks good I played with your file it does render fast and look good now I have to try and mimic the afect.


I’m the author of that technique. I’m very glad to see this technique passes over the frontiers of 3D packages and you guys find it useful.

Well done Matt!

Btw, this technique is useful also to fake scatering and SSS effects as I showed in the original thread about this trick:


Remember since this technique serves to accomplish the radiance effect, we need to mix it with the ambient occlusion effect to simulate the Global Illumination “look” appropriately.

I look forward to seeing what you guys do over this technique :slight_smile:

Best Regards,


Gerardo :Z :smiley:

Welcome to Elysiun.

Yeah neat effect.

Hello there Gerardo,

That is great, thank you very much for sharing your techniques, it’s an excellent tutorial! Also thank you for the link to the CGTalk thread, I hadn’t seen that one before. :smiley:

Yeah, I think that especially LW and Blender share aspects of their workflow for certain areas, which make it pretty easy to use techniques from the one in the other.

Again thanks alot!

Hey there Koba, yeah I just put Glow on as a post process through the sequencer while playing around with the possibilities. :smiley:

Matt :slight_smile:

Oh crap…I didn’t see that this thread had been replied to.

Anyway, I’m wondering how this technique could be improved with the new node editor. I am also wondering if your SSS technique is different from the attempts to fake SSS with the node editor.

An SSS .blend would not go unappreciated either!


This is an excellent trick… especially for simple animation stuff. Is anyone working on a blender tutorial for this method? I read the LW tutorial and understand the basic ideas, but don’t understand exactly how one would do this in Blender. I’ve been a Blender user for some time, but my knowledge of the program has some holes in it. I’d really get excited over a blender-specific explanation of how to do this.

Thanks again for putting this up on the forum, it really is cool!

hi can u provide the link again,rhe file is not on this server anymore?