New texture: VRayFastDirt

[max@mfx]

Could you write a faster version of the dirt shader (or add an option to the current) that interpolates between samples much like the irradiance map does? I have a really hard time remapping the light grey colors to black (with at ramp) just because there are so few black samples and the remapping is done prior to final pixel sampling is done. If the shader would interpolate then the pixel samplings missing the black dots would have the correct grey color. It should work to do something like this with the DMC right?

Another obvious plus is the speed improvements and smoothness, at least with stills where flicker isn't that big an issue.

As a matter of facts, this is already how I produce soft shadows, I put white in the GI env color and just have the irradiance map on. It gives superior results for stills compared to using a VRayDirt shader.

Thoughts?
/Max

[bigbossfr]

Hi,
Why do you not use the ambient occlusion in the GI tab of the render global ?
With this, you can save your occlusion in a irradiance map.

[max@mfx]

Hmm, not sure what you mean. Where is that option? Is it in the 2.0 release for Maya?

As a side note, what I want to do is use the dirt for mapping purposes (more specifically mapping reflection color for dirt in cracks) so I need a fast, smooth texture node.

/Max

[bigbossfr]

The option is here : http://www.spot3d.com/vray/help/maya..._params_gi.htm
Parameters -> Ambient Occlusion

Use a Vray object property node to disable GI on some objects (it will disable the occlusion).

[vlado]

You can do it from the GI settings, but then you won't be able to use it in a texture. I guess Max wants to blend textures or materials based on this texture.

To answer the original question - yes, it is possible to implement caching for VRayDirt; I believe it is somewhere on the "to do" list. In the meantime, baking to a regular texture might be an option too.

Best regards,
Vlado

[max@mfx]

That would be powerful. Couldn't occlusion be calculated in the irradiance map phase and stored on those samples? That is in my mind the exact calculation that has to be done and most of the job is already made by the irradience engine, sampling a hemisphere and weighting it etc.

Then it would be nice to have a texture to pull this pre pass occlusion info and use in the final pass. A clear limitation of this texture would obviously be that it has to be represented by a fixed color (white) in the pre pass, much like the current VRayDirt option "ignore for gi". Alternatively it could do brute force occlusion for the pre pass to get a closer result for GI purposes.

Best Regards,
Max