V-Ray and layering normal/bump maps

[jensl]

Hi,

I'm wondering about normal/displacement/bump maps in V-Ray for Maya, as it seems there's been some talk on the Max forums about getting bump/normal maps into extraTex/dirt passes, which would be handy. Also, does anyone has a good method for blending bumps and normals?

Initially I was trying to find an easy way to maintain independent bump and normal maps, as it is often easiest to get them looking good individually, but when mixing them in Shader Map Pro/CrazyBump it's a slow process. Blending bump and normal maps is doable using multiple bump2d nodes, but V-RayMtl doesn't use that as it's part of the shader. I've made some progress by plugging the normal map into a layered texture, and then extracting bump into rgb, putting them into the layered shader using lighten, lighten, and multiply (respectively). It works but is far from perfect and likely not much faster than just taking the time to blend them in Shader Map Pro. Is there an easy way to blend a bump with normal map, using Maya nodes so it's not a process of tweaking the image files, exporting a normal map, reloading the file, and rendering? Thanks,

Jens

[vlado]

Hm, good question. One way would be to create two otherwise identical materials, but one with bump and the other with a normal map, and then use VRayBlendMtl to blend them.

Best regards,
Vlado

[jensl]

Ahh, that is another solution. But that would be slower than using ramps, especially if there are low glossy reflections in the shader.

[jensl]

Vlado your reply got me thinking about the method I've been using for getting dirt with bump: to pipe a VRayDirt node into the diffuse color of a VRayMtl without any refl/refr. This seems to look correct, but I realized I'm not sure if there is a more accurate method.

Also, I'm curious about doing this for a normals pass with bump. I'm unsure of how to do a normals pass in V-Ray that's not a render element (which won't honor bump), for MR there's an AO mode function to switch to normals, but I haven't found something to that effect in VRayDirt. Is this possible?

[vlado]

You can do it in a .vrscene file, if you attach the samplerInfo texture to a BRDFLight plugin and put this inside a BRDFBump plugin. I don't think you can do this directly in Maya though; I guess we'll have to expose the BRDFBump plugin directly as a material in Maya.

Best regards,
Vlado

[jensl]

Thanks for your reply, Vlado. Looking forward to BRDFBump in Maya-

Jens