Radiosity rendering destroys my textures!

Support Compositing and Post Processing
#1

I’ve tried to post in “textures and lighting” but not solved the issue, then I try here:

I’ve encountered a strange behavior of the internal blender rendering engine in my tests.

I’ve a scene with a mesh (a tree), some spotlights and a ICOSphere simulating G.I. Of course I have a material also, and I’ve applied that to my Tree.
The material is a simple simulation of a tree bark, it include some textures, 2 of those textures are mapped to Displace my Tree, in order to render a sort of cracks in my surface.

The following images show the problem I’ve encountered. I’ve added an Edge to my rendering for an immediate spotting of the issue.

1 - When I render using the spots only as a source of lights and disabling Radiosity for my scene I obtain this result that’s what I’d expect from my displacement mapping:

http://img237.imageshack.us/img237/8084/noradfl9.png

The following image otherwise, shows the result of the rendering with Radiosity enabled and the disastrous effect that feature produces over my textures. As you can see the Radiosity render destroys every Displace Map I’d like to apply to my tree, turning the bark surface in a smooth one, pretty unrealistic:

http://img358.imageshack.us/img358/1695/radre7.png

I’ve tried some more tests with Radiosity and Displacement map on material all of these leading to the same issue.
What I have to do to get around the problem? Is that an issue of the Blender internal engine?

#2

I can’t solve the problem… I’m starting to think it’s an issue of the internal rendering engine.

#3

I’m not sure but it just might be that the GI simulation screws your texture up. The radiosity just spreads the light to uniformly over the surface washing out the small shadows your bumpmap / dispmap gives you destroying the displacement effect. You might want to try to increas the displacement or change your lightning setup to give more sharp shadows for your displacement map.

#4

It should be the case of a Norm Bump where there isn’t geometry modifications.

I think Displacement map generates real geometry modifications in rendering phase then radiosity couldn’t destroy the vertices, taking instead those in account like all other vertices.
I tried to enhance my displacement map in Map To panel, but I reached the Max and nothing changed :no:

I even tried to change my IcoSphere GI with an Icosphere bigger and an Icosphere smaller, and the Radiosity settings, from Size of Hemires to Number of iterations, but nothing, I got the same result.

If I want to keep my Displacement map I must disable radiosity…:mad:

#5

Radiosity changes the geometry which effects the displacement. Maybe try baking it first to get the radiosity effect then render.

#6

You spend some time modeling your objects, texturing them and setting up the Displacement textures and… then Radiosity rendering modifies those by its own?!

I really think it’s a bug…

When I perform Collect meshes, blender doesn’t take in account the geometry displacement the textures will perform in rendering phase, therefore I obtain same result, with a mesh very simplified. With that surface the attempting blender performs to displace it, is really useless because it brings to a bigger destruction of the mesh itself making the things even worse!

#7

It’s not a bug it’s how radiosity works. Maybe try this http://wiki.blender.org/index.php/Manual/Displace_Modifier

You can tweak then apply it. From there bake radiosity.

#8

You may also try using a different lighting method to achieve the same result. Maybe a fake GI hemi lamp + AO or the old spot lamp trick. Or you could try my favorite render engine yafray and get real GI.

Have you tried using AO add instead, it might look somewhat like what you want?

#9

I’m definitely going to use AO, with the last improvement that make this feature QMC Adaptive, the grain image AO was used to generate are memory now! I’m waiting new shaded AO impatiently.

Anyway, it’s a pity Radiosity deforms geometry so much, I think it occurs in Blender only, many years rendering in POVRay never generated similar effects. I’m keeping the hope Blender can, sooner or later, manage radiosity and maybe GI in a better way than this.

I’d like to learn YafRay but I’m afraid the never-ending time it requires to render even a simple image in comparison of Blender Internal Engine… anyway its GI is really really good! Can you give me a link for a good tutorial about YafRay?

#10

Radiosity in blender is vertex light on a face. It uses adaptive subdivide (or not) to produce the effect. It’s nice but not as nice as real GI. Radiosity is an old algorithm in Blender to allow emit values on a mesh (an emitter) to produce a light effect. I’d strongly recommend using another method for the GI effect to keep you geometry under control.

Go to http://www.yafray.org and poke around. It’s easier than you think and faster than you think too. Plus if you like you can even try the new yaf(a)ray versions. BI is fast but no where near the quality of yafray.

#11

thank you. I’ll try for sure.