Increased rendertime with many render elements

V-Ray V-Ray for 3ds Max General
1

I am doing some testrenders with some pretty heavy scenes.

With a “pure” render without any extra elements, not deep or anything, the rendertime is approx. 3 minutes.
When I add render elements, this suddenly becomes 20 mins instead. While I understand that the rendertimes will be somewhat higher, I just don`t understand why it is THIS high.

I added all the render elements needed to rebuild the images in Nuke (diffuse, reflection, etc). In addition there is Deep, Velocity, AO (radius:1000, samples:128 ), five light selection elements in normal mode, and a few cases of Sampler info. The sampler info contains things like UVW coordinates (several types), points and normal vector.

Can those things really add that much to the rendertime? are there any render elements I should be particulary aware of?

2

Hello,

Could you try with all the render elements except AO ? My guess is that it causes that massive increase in the render time..

If it turns out to be the problem - you said it is with 128 samples - you mean 128 subdivs ? That is quite a lot (16384 rays for every shading point) - are you getting bad results with lower value ?

Best regards,
Yavor

3

It`s the AO that is the problem as you said :slight_smile:
The scene is 10x bigger than its real world scale, which is why the radius is so high. I just didn`t think it would be that taxing. But anyway, thanks for the help :smile:

4

I think the issue is with the samples, not the radius - if you keep the radius to 1000 but lower the samples to something like 8 or even lower ?

5

I will do some test to see where i land. I was just suprised by the render time, but now that I know it`s no problem :slight_smile:

6

As others have said, it’s the AO that’s adding to your render time the most.

Even with huge 360 VR renders, I rarely ever go above 64 subdivs on the AO settings. And generally, 32 is plenty.

7

Try turning off “consider for antialiasing” in your extratex passes if that’s how you’re setting up the AO passes too.

8

Its alright guys. I just wasn`t aware that AO used that much horespower. Previously I only used it a tiny bit to get more interesting shadows, but this time I needed more for post. I will spend some time to figure out how much AO I really need :slight_smile:

9

I am confused now. I though subdivs are handled by VRay automatically now? The VRayDirt subdivs don’t? I always assumed is was a bug that you could still enter subdivs there and it’s not grayed out.

10

If you can enter subdivs you probably have local subdivs enabled in Vray.

When it comes to AO its different. It`s a texture map (VrayDirt), not part of the render. That`s why its subdivs are separate.