Problem with "Invisible to Camera" geometry

[David_Murgatroyd]

Hi, I'm getting some strange artifacts when some objects in the scene are set to invisible to camera.

Here is the basic scene with all objects visible:



and here is the scene with the foreground walls removed:



The vertical speckled grey bands in the centre of the image are not expected. They seem to occur where two objects are hard up against each other, but it is not consistently so.

Here is a scene I was working on whien I first noticed the problem:



As you can see, it ruins the image. Are there any solutions?

Here's the scene in case anyone wants to try repeating the results:

http://www.rockhunter.com.au/vrayfor...RA_PROBLEM.max

[vlado]

Set the secondary rays bias in the Global Switches rollout to a small positive value like 0.001 and it will be fine. This will help VRay to get past the overlapping faces.

Best regards,
Vlado

[David_Murgatroyd]

Thanks, Vlado. That helped a lot, but there are still some blotches left in my architectural scene which do not seem to disappear. I've tried secondary ray bias of 0.001 up to 0.020 without success. Any ideas how I can remove the blotches all together?

Here's the improved version (notice to blotches in background colour):

[vlado]

What is the value of the "Max. transp. levels" parameter?

Best regards,
Vlado

[David_Murgatroyd]

Max. transp. levels is currently set to 12.

[David_Murgatroyd]

I just tried setting Max.transp levels at 25, and it seems to have done the job! Thanks again, Vlado.

[Da_elf]

in the scene you have there im just curious. what are the hidden from camera objects that you have in the scene infront of the building? tree reflection maps?

[David_Murgatroyd]

It's an atrium scene, so I needed a cutaway view so as not to distort the perspective too much. Because of the particular viewing angle, clipping planes were not going to work. THe hidden from camera objects are two facades of the atrium.

[Da_elf]

ah i thought as much.