VRAY5 strange cuts in volumes in render

[skulldoestalkfast]

hi , these are exemples of strange issues in Vray5 render: when I change the camera focal for example from 100mm to 150mm the render cuts parts of the neck of the character... very strange, like if some boolean op was active. here are 3 images
to illustrate the issue.

hardware is PC windows 10, 2 RTX5000 cards, 64GB ram, 10coresxeon.

any idea of the root of problem?

thanks
PF

[shaio]

Hey skulldoestalkfast ,

this looks odd. Does it still happen if you remove the materials and or any V-Ray tags that you have attached to the mesh? Are you using the V-Ray Physical Camera or a regular Cinema 4D camera. Sharing a very simplified version of the scene where the issue is still reproducible would be very helpful for us to investigate what could be the issue.

Thank you for the feedback!

[skulldoestalkfast]

hi Ivan, i will remove the materials and tags this afternoon in a few hours and probe it again. The same strange issue happens sometimes when I activate the "view dependent" in the displacement tag. It is like if a kind of odd clipping plane or boolean was active. If I put my
camera on a circle spline to align it, and that I reduce the diameter of the line too much, same things happens, as if the camera object was cutting through the volume.
As soon as I try I will post the results and if needed I will share a scene

[skulldoestalkfast]

made some tests this morning, removed all the tags , hairs, and even SSS material. It looks like the issue comes from the "view dependent" option in displacement when the edge size is small.

[shaio]

I wasn't able to reproduce this on my end, but unfortunately It might be an expected behavior since the View dependent parameter is an optimization option, and basically it calculates the displacement based on the camera distance and such which explains why it dissapears when you deactivate the parameter. Can you try to find a different view or move the camera back then frame the object in the middle but leave some blank space on all four sides of the frame? After that you can render again and check if it still reproduces.

[skulldoestalkfast]

Thanks I will try that