Long render time with translucent material + Crash with Vray RT.

[Ihno]

I'm trying to render a scene in which I use the two-sided mtl.
The scene itself isn't very heavy geometry and lighting wise.
But it takes 8h for a full HD frame with a threshold of 0.009 on a I7 6700k @4ghz

Here is what it looks like:



Its b bunch of springs inside of a translucent fabric.
I know this takes some time to compute but I thought 2-3 h would be sufficient.
I use the refraction instead of the opacity on the base Vray-Mtl because I can blur it. Is that a problem?

It crashes during the building bvh stage when I try to render it with RT.
And a quick test with vray-next (today's nightly) seems to take even longer.
I'm running out of Ideas.

Here is the scene:
https://drive.google.com/file/d/1YqF...ew?usp=sharing

Edit:
I used:
Max 2017 + Vray 3.60.03
Max 2018 for the test with Next.

[Ihno]

I'm slowly approaching a better render time.
Using regular methods like: Baking the maps and making the lighting simpler.
I'm still not sure if there is something wrong with my setup.

On a side node:
I noticed that a baked bump normals map results in a very different (less strong) bump than my color to bump setup. Even though, I baked that exact setup.
I'll use a baked grayscale map and pipe it through the color to bump but I'm curious.

[Ihno]

Just want to add here that I'm now on vray next and currently rendering a scene with a few hundred of those.
I'm baffled! It takes around 3 minutes on a GTX 1080 and a i7 5960x. Thats a speed increase!
Seems like glossy refractions aren't that much of a problem anymore!

[joconnell]

Oh that's great news! Glossy refractions was always the biggest killer for me, I wonder is it all the light cache based speed ups working?

[Ihno]

In my case BF+BF 4 bounces was slightly faster but that's kind of preview state with sun+sky. I used a noise threshold of 0.008 though since it rendered so fast.
I'll rework the lighting and I think I'll end up with about 10 min.
I think the light Cache will then be worth it's calculation time in animation setting.

Glad to see you here more often!

[Muhammed_Hamed]

Sampling of refractions and SSS has been improved quite a lot in Vray next. Nice to see this in action
And by the way, the more lights you use, the fastest your render will be with adaptive lights.