Motion Blur render times

[cantu.john866]

I am getting much faster render times with the Motion Blur box checked. I have a typical vray sun sky scene with a water plane using displacement and a yacht. With the MB button checked I get render times 15-45minutes, the same exact scene without MB checked is about 4-8hours. Can someone explain what exactly checking this function is doing to my scene to speed up the times so dramatically? I noticed the water quality is lower and that has something to do with it.

I know MB is not enabled but when it is I don't want to lose the "turbo button" aspect.

[**dubs**]

Re: Motion Blur render times

Hello John,

With motion blur, what is that in relation to?:

A setting in The Vray Render Options? (blurring your HDRI image?) Or are you enabling motion blur on a specific material i.e. water?. . . specifically a texture?

I'm unsure what it is you are applying blur to, which is allowing the calculation time to drop so dramatically. . .

Cheers

Stu

[Micha_cg]

Re: Motion Blur render times

I tested it at a studio scene (material test, also some displacement materials) here. With MB enabled (camera settings) the render time was longer, from 2:18 to 3:09 (min:s). So, I don't see the turbo at thi scene here. Could be good to know, why you got the effect.

[cantu.john866]

Re: Motion Blur render times

Here is a screen of the difference, in the most dramatic view (the sky/sun setting were altered). Its the camera MB.





Micha, Yes I think if my scene were optimized better it would render the non-mb scene properly at the lower times.

[camionero]

Re: Motion Blur render times

HOw did you make the water ???????thats not only noise or perlin noise right??

[cantu.john866]

Re: Motion Blur render times


I used a rough displacement map plus the noise/bump map (different rough map than the water) on a flat plane. Its hard to get resolutions above 2800 with the displacement settings as they are though.

[Micha_cg]

Re: Motion Blur render times

Bad news: motion blur enabled and the displacement effect is rendered as bump only.

[**dubs**]

Re: Motion Blur render times

That would explain why the waves don't look so high in the non-MB rendering!

. . . and also the effect on the render time! (displacement allows Vray to create a special mesh with more detail over a bump, more polygons, more calculation. . .)

Nice bit of detective work Micha!

So. . . this means if you disable motion blur. . . and replace you're displacement map with a bump map, you'll get a very similar render time!? ???

Hmmmmmm. . . I've got an idea. . . Keep the displacement, but in your Vray Render Options>Displacement adjust the 'Edge Length' from 4 to say. . . 12? and see what happens? I think the quality will be almost as good as you're displaced (non-MB) image. . . but the render time will drop, hopefully dramatically!

Look forward to hearing about this one!

Kind regards

Stu