Textures Not Blending Properly

[jamesgclark]

I am not sure if anyone else has encountered this issue. I saw a few posts about blending materials, but I think my issue is more about how my textures are blending, which I think would be described as 'compositing' in Max VRay terms.
I just did a quick test last night on vRay for Modo with a scene that I built a while back. I just loading my scene and adding VRay GI to do a quick render with VRay, but a lot of my materials are not compositing the texture maps correctly. I blend a lot of textures, materials and procedurals in my shader tree. I am sure it is not the most efficient way to work, but I am more of an artist than a technician and I get the result I desire.
I did a render with Modo and one with VRay so you can compare them and I took a screen grab of part of my shader tree to give you an idea of my working process. FYI, I took out the glass in the VRay render because it is is not rendering correctly. Please let me know if this is a bug or if there is something that I need to do differently.

[vladimir.nedev]

We don't support the occlusion texture completely, so that maybe one reason for the difference.
Another possibility with "group masks" is that in V-Ray for MODO only the textureable effects of the material are blended.
Non-textureable effects, like "match specular", "reflection type" or "use refractive index", are always taken from the top-most material.

If you send me the scene (to vladimir.nedev [at] chaosgroup [dot] com , you can uploaded it on dropbox or wetransfer and send me a link),
I can take a look where the difference is coming from in your case.
Maybe include the windows as well, I will be trying to do some improvements for the translation of transparent materials.

Greetings,
Vladimir Nedev

[jamesgclark]

Hi Vlad,

Thanks for the reply. Ya, I think that the the occlusion could be causing issues on some of my materials. It probably is causing it on the chair leather and maybe even the glass, but I did not use occlusions on all of my materials. Actually, I made this scene before occlusions were even an option. So I have added occlusions to some materials during my updates, but some of the materials showing up wrong are not using occlusions. For example, it looks like some materials that are supposed to be shinier materials are showing a lot more of the diffuse map than the in Modo render.
As far as group masks go, I read all the threads that I found on this forum and I agree with the guy who was saying that it would be nice to figure out a way to keep it in the shader tree. Maybe you can set it up with a vray property on the group item, and have a properties tab where we can control the blending of materials in there. For example, I could make a group and throw a couple shaders and textures into it and then I can click on the group and add the vray blend property and that will create a tab where I can control which shader is on top of which, how they blend and which maps mask which shaders. I dont know if that would work, but if it did, it could be a good way of keeping things in the shader tree.
I made a trimmed down version of the scene with just the chair and the gyro rings and the glass. I think that is enough to illustrate what is going on. As I said, the entire scene is pretty big. So this is probably better. I will email you a link and make the subject "Modo: Textures Not Blending Properly". I think I included all the necessary textures, but let me know if there is anything missing. Also, I took it down to just one directional light and the modo environment, but the lighting was a wip and I figure youre more concerned with what is going on with my shader tree anyways.

Thanks,

James

[vladimir.nedev]

Thanks for the reply. Ya, I think that the the occlusion could be causing issues on some of my materials. It probably is causing it on the chair leather and maybe even the glass, but I did not use occlusions on all of my materials. Actually, I made this scene before occlusions were even an option. So I have added occlusions to some materials during my updates, but some of the materials showing up wrong are not using occlusions. For example, it looks like some materials that are supposed to be shinier materials are showing a lot more of the diffuse map than the in Modo render.

I received the scene and I think most of the issues are caused by unsupported textures, not by the group masks or texture blending.
Some of the unsupported textures in your scene:
- weight map texture (it works only for a V-Ray Proxy exported from another DCC app), that's causing the red-blue color on the chair
- occlusion texture (we only support the uniform mode somewhat, and you have a lot of occlusion textures with concavity, convexity, down slope, etc modes)
- MODO noise texture
The Event Log has information on supported textures after a V-Ray render completes.

Also we don't have an exact implementation of MODO's specular BRDF when the Shading Model is Traditional or Energy Conserving, so it is possible that the hi-lights in V-Ray are different.

You can subscribe to this thread as I will post here when I have improvements/support for any of these procedural textures.

You can see the currently supported MODO features on this page : http://docs.chaosgroup.com/display/V...+Compatibility

As far as group masks go, I read all the threads that I found on this forum and I agree with the guy who was saying that it would be nice to figure out a way to keep it in the shader tree. Maybe you can set it up with a vray property on the group item, and have a properties tab where we can control the blending of materials in there. For example, I could make a group and throw a couple shaders and textures into it and then I can click on the group and add the vray blend property and that will create a tab where I can control which shader is on top of which, how they blend and which maps mask which shaders. I dont know if that would work, but if it did, it could be a good way of keeping things in the shader tree.

The group masks should work as they do in MODO.
I think the discussion you talk about concerns the V-Ray Blend Material, not group masks.
At some point the V-Ray Blend Material will allow you to select material group items as its sub-materials, so you can have the sub-material's textures in the shader tree.

Right now, for blending materials entirely in the Shader Tree, you can use multiple Shader items.
This works in both MODO and V-Ray and keeps everything (materials and textures) in the Shader Tree.
I am attaching an example of this shader blend - normal.zip

It can be very confusing and I don't think the MODO help even mentions what the Shader item actually does.
You can think as each Material item as defining constant values for the various properties (diffuse color, specular color, roughness) etc.
You then have textures that define varying properties of the same material (which property exactly is defined by the texture's effect).
If you have 2 Material items and a texture with the group/layer mask effect between them, what happens is that the material properties get blended together.
It is the Shader item that does the light calculations, each Shader item is equivalent to a sub-material in a V-Ray Blend Material.

I think I included all the necessary textures, but let me know if there is anything missing

Some of the textures are missing, did you use "Consolidate scene" before sending ?
Can you send me the original full scene with textures (after doing a consolidate scene).
It contains a lot of different combinations of noise and occlusion and it will be a very nice test when I get to implementing those.

Greetings,
Vladimir Nedev

[jamesgclark]

Ok. Thanks for having a look.

Yeah, a lot of my materials were made before Modo had the physically based shader option.

I think I got confused by the group masks because I usually use weight map textures and occlusions as masks. So my shaders with group masks are not showing up correctly. I still dont think that I am clear on the difference between the VRay blend material and blending materials using groups and masking? I havent looked at your example yet though. Maybe that will help. I use VRay in Max, and it seems like the blend material and modo's group masking are used to achieve that same result.

I do get confused by Shaders vs Materials. I was taught to use just one shader item at the top of my shader tree. Sometimes I use a separate one if I want to mix IR and Monte Carlo per materials, but I dont really ever use it for much else. And I get extra confused because different softwares seem to use different terminology. I learned Maya first, then Modo and now I use Max. So I tend to think of shaders and materials synonymously, even though I know that is not the case, and I often say shader when I am talking about materials.

[vladimir.nedev]

I think I got confused by the group masks because I usually use weight map textures and occlusions as masks. So my shaders with group masks are not showing up correctly. I still dont think that I am clear on the difference between the VRay blend material and blending materials using groups and masking? I havent looked at your example yet though. Maybe that will help. I use VRay in Max, and it seems like the blend material and modo's group masking are used to achieve that same result.

They can be used to achieve similar results, but the blend material can do stuff that blending using groups and masking cannot.
Like having several reflection layers with different glossiness/roughness values and different normals. My example shows this.
This forum post from the MODO forums explains the Shader blending very well:
http://community.thefoundry.co.uk/di...84626&p=762735
This type of blending is the equivalent of V-Ray's blend material.

I do get confused by Shaders vs Materials. I was taught to use just one shader item at the top of my shader tree. Sometimes I use a separate one if I want to mix IR and Monte Carlo per materials, but I dont really ever use it for much else. And I get extra confused because different softwares seem to use different terminology. I learned Maya first, then Modo and now I use Max. So I tend to think of shaders and materials synonymously, even though I know that is not the case, and I often say shader when I am talking about materials.

Yes, it is confusing, not sure what's behind the MODO way of calling these things and whether it is accurate.

Greetings,
Vladimir Nedev