What could be causing these Black Splotches?

[harperperkins]

MegaDave (hehe), check Nikki's post earlier...it's not that you can't use falloffs, it's just be sure that within the falloff map, if you're using fresnel, you should have the "Override IOR" box checked.

As for quick test renders, I'd expect it's just like we've discussed before over at the Depot...regardless of your engine, set up the lighting with a gray/white scene, refine the settings to get the quality you're looking for, then save a preset or write them down or whatever, then drop all the settings for your tests, then re-up when you go to render your final.

ME

[gilpo]

Something else to check:

We had a problematic scene and we traced it to a material with a falloff map in the reflect AND had vray's "fresnel" box checked. As a result it seemed to be trying to do a double falloff and caused problems similar to what you're experiencing.

Just a thought.

[MegaPixel]

Thanks guys for all your input. I'm basically going over the scene with a fine comb at the moment and tryign to eliminate all fresnels and other suggestions made earlier. I'll give this scene another go this weekend and see what happens.

Daver

[jaggos]

make sure that the slaves can have access to your maps and materials, sometime i get similar problems and usually are related to DR.

[MegaPixel]

Well I think you are on to something there jaggo, both times I've seen the splotchess, I happened to be using Distributed Rendering. I can't seem to reproduce it when I do test renders on my workstation alone.

[jaggos]

quick trick for you, run MAX and load your scene trough your network and hit render, so every slave will be accessing trough common path. simplified
run= Max
file= open
my network places= navigate to your file
select file.
basicly you'll runnig the file on your workstation through the network.

hope its clear.

[vlado]

If you are still having problems, it might be easier to simply send us a part of the problemmatic scene so that we can check it out.

Best regards,
Vlado

[MegaPixel]

Well guys, I've done several things to the scene since I first posted about it, most of which involved going over the scene materials with a fine tooth comb and removing questionable falloff maps that didn't really need to be there. I havn't been able to completly rerender the spherical 360 of the kitchen again, but a few isolated test renders seem to show that the black spots are gone now.

Here is where I think most of my problems are originating from:

1 - Using varius shaders from downloaded .mat files like "deetee-VRay_Compilation.mat" which were designed from older Vray builds

2 - Blindly merging materialized objects from purchased collections like "Evermotion - ArchInteriors Vol. 2" without going over each object with a fine tooth comb

I'm noticing some fairly wild sampling values in materials that I use from older versions of Vray that are between 50 and 80 which most likely had a huge impact on my previous rendering performance.

So as a relativily newer user of Vray, are there any tips one could offer me as far as proper scene material devlopment practices goes? Thanks for everyone's input so far - Dave

[DaForce]

woo.. the main thing is to keep those subdivs under control.
So if your using glossys start at 8 and work your way up until you get a decent render. Between 12-20 usually gives good results in more circumstances (for reflection glossys)

And as Nikki said if your using falloff and fresnel make sure that Override IOR IS ticked and also have the fresnel tick box UNTICKED

Blend maps will often slow things down. As the GI has to be calculated twice. (once for each material)

[MegaPixel]

Finally, a Success! I don't seem to have the strange black spots anymore. Again, I attribute this to comments made in my previous post above. I also got the scene to render alot quicker my trimming out all of those extra subdivs in the junk merged materials. Now I can finally move onto to color correcting and higher res - final output.

http://www.cgvisions.com/temp/success_1024.jpg

This shot took 2 1/2 hours using DR (IR/QMC) with:
- One 3.2 Xeon Dell Workstation (4 Gigs w3/GB switch)
- Three Dual 3.4 Xeon Dell Racks (2 Gigs w3/GB switch)

[DaForce]

Looking good.

Great to hear you got it sorted!!

[ene.xis]

yeah! it looks great!
glad u sorted that one out!

[harperperkins]

Awesome, Dave!

And, as always, great attention to detail in your models!

Matt