Xgen Cuda rendering issue

V-Ray V-Ray for Maya General
1

Hi Guys,

First post here so please let me know if I’m in the wrong place etc.

I’m working with Xgen Interactive Grooming in Maya and curious if Vray using CUDA can render xgen hair the same way it does using CPU?. Appears using CUDA renders the hair as screen facing spline/cards rather than 3d tubes with rounded ends.
I tried applying the Hair Geometry attribute in the shape node but it only adds control of tessellation levels. I tried to find some info on this subject but without any luck which brings me here. If someone could point me in the right direction that would greatly appreciated.

Maya 2018.2
Vray 3.60.04

Thanks,

CPU.jpg
CPU.jpg1024×1024 100 KB

CUDA.jpg
CUDA.jpg1024×1024 106 KB

Viewport.jpg
Viewport.jpg1024×1024 68.4 KB

2

Is it possible to send us your test scene so we could reproduce the same results here on our side?

3

The difference comes because the GPU does not use embree and thus uses different hair primitives (see the little caps the hairs have on the CPU - that’s the tell-tale sign for embree).
You would need to tessellate your hair strands to make it look better on the GPU, there’s no other way currently. You can add more segments to the strands, or the dynamic tessellation attributes.
In either case, it will not look identical between CPU and GPU, as they are different render engines.