PDA

View Full Version : vray force backface killing and vray sun


silver619
08-17-2011, 12:44 AM
Hey guys,

Does anyone know of a way to get force backface culling to work when using a vray sun. It completely screws up lighting when a sun is in the scene.

thev
08-17-2011, 02:44 PM
There is an option for this in V-Ray global settings...

Best regards,
Vlado

silver619
08-17-2011, 07:31 PM
Yes i am using the option and thats the problem. All lighting is blown out when i use it. I have tested it without the vray sun and physical camera and it works fine, but when i add those its all blown out and lighting is completdly wrong and goes through walls as well. I am trying this on a friends system as he suggested i try vray since i use mental ray. He uses vray 2. Any suggestions would be apreciated.

dmarques1177
08-17-2011, 11:11 PM
I have never used v-ray sun n sky, was actually looking into it the other day to make some test renders but haven't had time.

Did you try lowering the multiplier to say .01?

PerfectLine
08-18-2011, 01:07 AM
Maybe your scene scale is setup such that the shadow bias is missing geometry?

So is it a cube where the backfaces are facing inward? The shadow bias on the default Vray sun is 0.020. Sometimes I make that 0.002

Testing here it is working for me with Vray sun. This is a closed cube with faces reversed so they are facing inward. Vray sun and sky turned on.

Aalavi
08-18-2011, 04:16 AM
Make sure the post intergalactic interference does not interfere in the global settings and also make sure that the photometric internal variable scale is compatible....

kingcorn
08-18-2011, 04:29 AM
I think i have faced this problem before. Why dont u try adjusting the baboon factor of the sun values. Below if an example image of what i achieved.

http://www.wallmoment.com/UPLOADED%20WALLPAPERS/Animals/Baboon/Baboon%20(11).jpg

silver619
08-18-2011, 03:06 PM
Maybe your scene scale is setup such that the shadow bias is missing geometry?

So is it a cube where the backfaces are facing inward? The shadow bias on the default Vray sun is 0.020. Sometimes I make that 0.002

Testing here it is working for me with Vray sun. This is a closed cube with faces reversed so they are facing inward. Vray sun and sky turned on.


Thanks for the reply man. Could you please tell me which version of vray and maya that you are using. I decided to try another system with the demo version, its vray 2 demo and maya 2012 and still gives same problem.

thanks in advance.

silver619
08-19-2011, 03:54 AM
Maybe your scene scale is setup such that the shadow bias is missing geometry?

So is it a cube where the backfaces are facing inward? The shadow bias on the default Vray sun is 0.020. Sometimes I make that 0.002

Testing here it is working for me with Vray sun. This is a closed cube with faces reversed so they are facing inward. Vray sun and sky turned on.


Hi again,

Sorry but seems i didnt pay proper attention to the image u sent. but it highlights my problem. If that box is closed then there shouldnt be any light in there. but the sun is sending light through anyways. I am attaching two images. First with a vray area light and second with sun and u wil see that the sun is sending light through everything. Third imabe is a shot inside the cube with backface culling off. Maybe this will give u an idea.

http://forums.cgsociety.org/attachment.php?attachmentid=163519&stc=1

http://forums.cgsociety.org/attachment.php?attachmentid=163520&stc=1

http://forums.cgsociety.org/attachment.php?attachmentid=163521&stc=1

CGTalk Moderation
08-19-2011, 03:54 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.