black holes in IR pass

[flipside]

Hi,

I'm rendering an old scene with vray .15 now. I set up lighting again to see how it would end up with my current vray knowledge and with lightcache.

I encountered the following problem:



In the IR pass you see these 'black holes' which result in dark spots.

Anyone else seen this kind of behavior? What could cause this, why aren't there any samples in these black holes?

I'm using IR map in first and LC for second bounce. No materials have GI wrappers above 1. Using only vray materials.

kind regards,

wouter

[natty]

hi

What are your Interp samples ? .. this sometimes can cause this when they are too low.. dont go below 20.

[flipside]

Hi natty,

been testing around, it seems to be a problem with displacement. I got two overbright or invalid material warnings, bot from displaced objects. If I use 3D mapping instead of 2D, the problem goes away.

I searched for black holes in the forum, and found a thread where you also say to increase interp samples. I must say I do not agree. Altough it's quite possible the black spots go away by doing so, it's only because the interpolation blurs them out. So the actual problem is still there. Like in my case, I think there's always something in the scene causing this problem. By increasing interp you blur out the GI quality, which isn't a good thing usually. I use low values all the time just to keep the nice GI detail In this scene the interp was = 20 though.

regards,

wouter

[natty]

So have you got displacement over all the objects shown here with black spots ?

[flipside]

No the displacement is on the floor and on a floor in the kitchen which isn't visible to the camera. Somehow it returns invalid colors and shoots invalid rays to the walls I guess.

[natty]

Back to the Interp samples ...how many hemispheric subdivs have you Used ?

Also there is a problem with UVW Mapping objects ..as you probably know, Returning Overbright mats..

[flipside]

I had 40 hsph

I tought the problem could occur when not mapping them? I have planer uvw maps on both displaced floors. But with 3D instead of 2D displacement the problem is gone.

[natty]

yeah forgot the Not ... lolol .. : )........ so if you turn off Displacement what happens then ?

[flipside]

then it's also fine

Must be something with the 2D displacement creating some weird geometry. The resolution paramater was pretty low.

I used 2D because it was faster in the older builds, and I had a slow PC in those days. Now I always use 3D displacement. That's why I'm not testing it further with the 2D displacement.

[vlado]

Apply the "Crop" option to your displacement maps and it will probably go away.

Best regards,
Vlado

[flipside]

I tried that too, but it didn't help when I stick to 2d displacement.