realism of the radiosity calculation


how far is the radiosity calculation real. i hasted a light from a rectangle onto a perpenticular extruded rectangle and the right part of the one side was darker than the other one.

all in all i get the impression that the radiosity result is not like the result i get from the gi in reyes renderer like 3delight or tempest.

i have not explored all the settigs for a long time went up the min and max setting and compared the results.
but mainly the result was often the same


how far?
far enough
(unless you want caustics, then get a raytracer)

actually the only fault I know of in the way blender does radiosity is that the light isn’t really reflected by elements and patches, it is absorbed, and emit from the center of the patch (problem 1), and emitted away from the face (problem 2).

the first problem can be overcome (to an extent) with good elMin elMax paMin and paMax settings

the second problem shows up if you wish to have, say, the sun shine in the window, reflect off a polished floor, and leave window shaped lighter areas on the cieling
again, this is better done with a raytracer

radiosity is not good enough on it’s own, good texturing is needed as well.

i realy appreciate the fact that this is more amodeling factor
which lowers the renderspeed a lot.

some how this looks different from what i am used when i use a global illumination system using raytracing like 3delight or tempest or strata.

blender output a more smooth plastic looking style. mh this may be linked to my ring object as well.

but sometime depending on the geometry the radiosity in blender forces a remodeling. those triangel artifacts are only able to get away when i lower the radiosity quality or remodel. and the first one isnt realy an option.

but i am just playing aroung and not complaining.


About this topic, I’ve spent a long time to understand
the radiosity realism, but without good result. Anyone can
help me? Take a look here:

i finaly understand it somehow.

i think that all settigs are relativ only. depending on you mesh you will get different results. i had a ground mesh one was low one was high subd and the casted shadow on it was very different.

i think there is only one think you can trust and that is your eye!!!

if you have problems using radiosity in blender just ask me.
spent the hole night to udnerstand it!