vray render problem - blotchy surfaces

[swobodny]

I am wondering if anybody may help - I am trying to get rid of the blotchy surfaces, to get a nice and smooth render, but I can't figure out what I am doing wrong - any ideas?

Thanks.

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[AubreyM]

It would help if you posted your render settings.

I will assume that your using light cache. Offhand I would look at your irradiance settings specifically the preset (Medium) and the HSph Subdivs (50-60). Also look at the Light Cache subdivisions (400-800).

Without seeing your settings it's all just a guess.

[salvador]

@Tomasz: I've been having the same problem here and I think I just finally cracked it (I guess you too since you didn't reply to the thread anymore). Apparently (said like this since I'm not quite a V-Ray expert) V-Ray needs a certain amount of light samples to work with. When an interior scene is lit by Sun+Sky alone, the walls and ceiling are lit by bounced light only, and if you have deflectors as in your case, the rays will be too scattered to get to a smooth surface look because of the low samples that could be collected. In my case, I turned back to the V-Ray lights on the windows, but checked "Skylight portal" and "Store with Irradiance map" on. Also used 24 shadow subdivs for each light. This way you can test and control the final quality with the sampler paramteters.