Strange problem with render regions... Can't find answer!

[OZRAY]

Hi Everyone!
This afternoon I got a very strange problem and can't find what's causing this...
Im currently setting up my lighting in my scene and for that purpose I was doing
region render to tune it. After good result, Im rendering a full frame and Doh!
All the floor get blasted! Why! ??? Look at my screenshots to understand.
The more biger is the region the more blasted it is!! Snif Snif....

Can someone explain and help me fix this please!!

[vlado]

What is the material on the floor and your GI settings?

Best regards,
Vlado

[OZRAY]

There is the settings.
It's standard VRayMtl on the ground.
What's strange is that the light cache and ir map are calculated correctly...
It's only the render part.
Im using the linear workflow with gamma at 1.8 and a VRaySky with colorcorrect float value.

It's working only with small region renders...

http://www.urbanimage.ca/settings.jpg

Thanks Vlado.

[vlado]

No idea then, without the scene. However if you send it to me at vlado@chaosgroup.com I can take a look to see what is wrong.

Best regards,
Vlado

[OZRAY]

I sent you the file but after investigating more I found how to fix it.
But I think that's a real bug.

Changing the Sample lookup from Overlapping to Density Based it render correctly!
Why ?? It's not normal that a small region render correcltly and the full image not?

Regards,

[vlado]

Ahh, so that's what it was; I looked at the file, but I missed this detail.

It is, in fact, normal, if you have a very large outside environment from which only a small portion is visible at the same time as the interior. With the "Overlapping" method, some of the outside samples can leak into the inside. This can be solved by using the "Density-based" method, or by turning on the "Check sample visibility" option.

Best regards,
Vlado

[OZRAY]

OMG...
I understand but what's the point with the render region that is working ?
(I need to understand)...

[vlado]

Because in the first region render, you don't see the outside at all; in the second region render a small part of it is visible, and it causes problems; in the full view render, even larger part of the outside is visible causing even more problems.

Best regards,
Vlado