Best way to fake radiosity in Blender 2.5?

So on the old blender I found the setting for radiosity but never got it working. Maybe because my shape was too weird (a transparent cube with rounded corners basically). Also I don’t know that I understood it and I maybe missed some key setting.

Now the new one doesn’t have it but it’s so much nicer to work in.

So what do we do to make it look like light is passing through my colorful clear object and casting colored shadows on the other side? Right now I’m resorting to a colored spotlight pointing where the shadow would fall. But it doesn’t look very good. The rest of the colored light gets washed out on my bright white plane but in other scenes it won’t.

Do I have to just photoshop this for now or what?

radiosity has been replace with indirect lighting n 2.5

and same idea add some emit and it will do the equivalent of radiosity


Hi… thanks for the info. So, there is indirect lighting… that’s good. What about lighting passing through an object to make the shadow a different color? Emit would emit colored light on all sides. I want a colored shadow, and only on the side where the shadow is cast. Is there a way to get this?

try it but i think it’s already doing that in 2.5!

make a test !


hi again - well, I tried changing every setting I can think of, but the effect is not very strong. I guess it is there. I want the shadow from this block to be very strongly orange. Instead I think I barely can see a tiny bit of orange, even though there is one lamp inside the block, and another outside.


ok an you upload the file
i’ll try a few things
not certain which parameters to change to get more effect here!

but may be normal or may have to use the ray trace version which is part of the render branch i guess

right now i think only the approximate mode is working in 2.53!

but even rneder branch is not complete and has many bugs in it


From the looks of it, I think you are attempting to render caustics. They are the random colored specs of light that shine through translucent and transparent objects.

If that’s the case, blender cannot yet render those. You’ll have to use another renderer, like Yafaray or Luxrender.

Good luck!

Have you changed the colour of the light shadow in the light settings? from black to your models colour?

ricky: ok, here is the file …

illusionist: Caustics would be nice and are part of what I’m thinking of. But mostly, I just think light passing through a orange glass/plastic/whatever block… would cast a very orange shadow. Here’s it’s 90% black shadow and only a little orange.

Dund: Good idea. Before, I added a second light that had the color I wanted. But just changing the shadow of the existing light makes a lot more sense. This might be as close as I can come to the effect I want.

Before and after:

Oh, I found the answer to the original question I think. It’s “indirect lighting” under the global options. Somehow I missed this though I guess it’s a big feature. If I give just one bounce, at .5, there’s a nice blue shadow. If I add more than one bounce, the base of the object starts to glow quite a bit and it doesn’t look natural (but kind of cool).

I’m still trying different settings though. Some perfect combination of fresnel, alpha, and blend seems to make the object a rich color but transparent enough to make the light cast a lot of blue in the shadow.

i did one with more transpa and less emit value and now fresnel
see pic

but always depends on the look you need


that looks pretty good too, the glow at the base is there without indirect lighting?

that’s moslty IL and your little lamp behind which i reduce the power a lot
to have darker scene

but depens what you need!

have fun with IL
happy 2.5

have a look on this one


eheh that’s more like what I was looking for. The IL option was always there I guess I just didn’t find it obvious. Maybe it should be a per-light option, so some lights bounce off surfaces and others don’t. Or if they wanted to be really realistic, it’s based on the light distance… a light that casts for 40 distance units will bounce if it hits something at 20.

Anyway I figured out with soft shadows it looks pretty nice. Everything turned too green though.

is ther a tutorial for GI in blender 2.53?

not certain but don’t think this is has anything to do with GI

IL is more the new radiosity in 2.5!

nice render but you coul try adding some halo around it may be but just a little

or add some spot lamp inside with color

did you check out the setting for the last file from share blender?

or like we did in NRK thread on volumetric add some volumetric around !

but if you want to experiment more with IL or radiosity then may be inside a few weeks Yafaray will be available for 2.5 but still experimental

but yafaray can make much higher quality rendering !

you can try it if available for vista

let me know if it works fine

i can’
t wait to get yafaray in 2,5 and it will be better integrated then the old one too
it will be something quit good to make very nice render


I hear people talk about yafaray a lot. Is it a mod of blender? Or totally different? I just started learning blender, I don’t know if I have the patience to learn something new. Once you get used to blender it’s not bad to use.

yafaray is an external renderer which is high quality and offers a lot more rendering choice then in blender internal

so if youwant to make super nice render yafaray is frist choice or other external one
like Luxrender

but you have to learn it and it takes some time to get used to
but ounce it works it gives results that are very impressive

may be later if you want to do much higher quyality you can learn it


I’m reading about it, and it looks like yafaray was a plugin for the old blender… you just model the scene with blender then choose yafaray to render. Is this possible in blender 2.5?