Precise/targeted undersampling

[Art48]

Hi,

I got to do a sand-blasted-like material with a grain size too tiny to do via a bumpmap. Now I tried adding simple noise in PS for that parts of the object and it works pretty good. Now I wonder if there is a possibility to do that directly in VRay by undersampling a specific material? I wanna keep the rest of the image normal but basically add noise in a single material.

As I said it's not feasible to do via bumpmap since it's too tiny.

[super gnu]

why not add the noise to the diffuse or reflection level maps? for really fine grained stuff i usually prefer that to doing bump mapping.

[Art48]

I don't want to alter anything. Basically I don't want to tinker around with a per-se good shader anymore, JUST add some noise. I mean it's not THAT big of a deal, since I can do it in PS also, but I was just wondering if there is an easy way to do it directly in max.

[super gnu]

you might be able to get the desired result by drastically reducing the subdiv multiplier on the object ( in vray properties) but id just do it in PS since the result will be adjustable.

[Art48]

The thing is that is only the value for the DMC sampler. Then AA will try to clean it up, resulting in higher rendertimes, am I right?. Maybe PS is the best option afterall...

[svetlozar.draganov]

Another option would be to render the object on a second pass with lower settings.
There are plenty of options to render specific objects in the scene in V-Ray 3.x and since the goal is to render a noisy image it won't take much time to do it as a second render.