brute-force is fast for DR?

[aristocratic3d]

as we know light cash is calculated only by workstation. so if one have multiple render nodes is it not better for him to use brute force so he gets support from his slaves?

 

Thanks

Abdullah

[Chris MacDonald]

Are you talking about primary, or secondary bounce? Light cache is terrible for primary.

[aristocratic3d]

I am talking about secondary of-course!

[Chris MacDonald]

Light cache is far quicker than brute force as a secondary; even if it has to process on one PC. How long is your light cache taking? Even on massive renders, I rarely have a light cache calculation that takes more than a couple of minutes; which is nothing given the rest of the render could be anything from 10 minutes to 12 hours.

[aristocratic3d]

Lets say I have 10 nodes 80 buckets to render frame. so if I use brute foruce I have all 80 buckets from the beginning to calculate. but for light cashe only my work station is calculating (if its true).

 

In such a case would any one use bruteforce?

[Chris MacDonald]

I still think Light Cache would be quicker. Why don't you just set up a test for comparison purposes?

 

It's also worth keeping in mind that if you're doing this for an animation then you will have to calculate brute force on every frame, unlike light cache which will calculate the whole animation at once.

[aristocratic3d]

You are right Mac, I must be a fool to think about brute force in this case.

However I saw a thread claiming that brute force is way too faster than before in vray3.0

[Justin Hunt]

yes faster than what brute force was in vray2, but still not as fast as IC/LC

[Francisco Penaloza]

I think first you need to narrow down what are you trying to achieve, or what you need to render. IRR, LC and brute force are different method to approximate GI each one of them has pros and cons.

 

If you are rendering a teapod, the time difference is almost nothing, if it is a complex interior, or a forest, a scene with everything moving, then Irr or LC won't be good enough.

Also with very large scenes and millions of objects or large displacement, LC start to take longer than usual (At least in V Ray 2)

So it is not just as simple as say, LC is faster than brute force. in Theory it should, but to get the same quality that Brute force produce, it will take a lot longer. Same thing with Irr.

 

Irr and LC are designed to be faster than Brute force, but with a quality penalty. This in most cases is "good enough" but in some cases Brute

force will perform just fine. The great advantage of brute force besides quality is setup time.

[Tommy L]

I usually use Irradience map (primary) and Light Cache (secondary). Ive had some huge prepass times though (1.5hrs for 6k render). Im not even sure what VRay is doing at that phase. Is it calculating the LC contribution to glossies?