Vray 3.5 cuda and cpu differences/rectangle light and refection.

[francomanko]

Ok, so i installed 3.5 and noticed that the cpu and cuda were producing quite different results with a material.

Firstly, looking at attached image I'm getting differences with renders when the glossy fresnel option is on. Also ( and this is regardless of if glossy fresnel is on or off) referring to the image you can see the reflection of the rectangle light in scene is non existant in the cuda render.


Also I think theres some issue with adding glossiness textures but its hard to test without cuda supporting glossiness renderelements. This has been an issue for a while, any eta on a fix?



I've attached a scene.

thanks

[savage309]

Glossy fresnel is not supported in CUDA yet.
Also, V-Ray GPU is a different render engine to V-Ray CPU - they might share common UI and most often will render quite close, but there will never be 1:1 match (nor this is our goal).
The thing with the glossy map could be a bug, but it is hard to say without the scene (even if it is very simple, it will be very helpful to have it here).

Best,
Blago.

[francomanko]

Hi thanks for reply, the scene is attached to the first post.

[savage309]

Hi thanks for reply, the scene is attached to the first post.

My bad, I missed that. The QAs will check to see if that is expected. Thanks!

Best,
Blago.

[francomanko]

cheers much appreciated

[francomanko]

Is there an eta on the render element for glossiness being fixed in ipr/cuda mode, as its a pain not having it

[savage309]

Is there an eta on the render element for glossiness being fixed in ipr/cuda mode, as its a pain not having it

The render elements between CPU and GPU are not expected to match. They are quite a different renders .. while the RGB result often might be very close, the same is not true for the render elements.
In the case, the GPU stores the light in the specular RE (since it is glossy reflection ...). I believe this should work for you and you can get the job done with that ?

Best,
Blago.

[francomanko]

im confused, i understand the bit about the cpu and gpu renders wont necessarily match, but are you saying that using the specular RE is a temporary workaround or the intended workflow? Because if its the intended workflow it would be weird (or at the very least unnecessarily confusing)

[savage309]

It seems to keep the speculars out of the reflection render element .. I made a note to figure out whats the most appropriate thing to do ...

Best,
Blago.