Light Cache Pre-filter Settings

[Bruce Hart]

Hi all,
I'm pretty new to Vray, and I am wondering about the Light Cache Pre-filter. My understanding is that it helps smooth out/blurs the light cache solution. The default for the prefilter is 10 but many seem to use a value of 100.

If anyone could please provide me with some guidlines as to when to use it and what numbers to use (and why), I would be grateful.

Thanks

[vlado]

It depends on what your other settings are; you can switch the primary engine to light cache too while adjusting this parameter so that you can see the results. The goal is to have the light cache relatively smooth without too much noise between the different samples.

Best regards,
Vlado

[Bruce Hart]

OK - thanks for the reply Vlado,
I've seen various tutorials where the pre-filter numbers can range from 10 to 100 to 1000 - which is quite a spread. I just wondered at the logic behind these numbers. As you say, you adjust until the solution is smooth.

Thanks again

[peterguthrie]

Do most people use this? Does it play more of a role in animations?

Just curious if I should be using it!

[voltron7]

Do most people use this? Does it play more of a role in animations?

Just curious if I should be using it!

I've tried it on some stills using "universal" settings and I really couldn't see any difference, on or off.

Good question, Bruce

[3DMK]

OK - thanks for the reply Vlado,
I've seen various tutorials where the pre-filter numbers can range from 10 to 100 to 1000 - which is quite a spread. I just wondered at the logic behind these numbers. As you say, you adjust until the solution is smooth.

Thanks again

Like Vlado said - Use light cach for primary & secondary bounce at first just to see exactly how clean/noisey your settings are.

From experience I have found that it is better to increase the light cache subdivisions rather than increase the Pre-filter amount as pre-filtering smooths everything too much & you loose light/shadow definition.
Pre-filtering is another one of those extra tools that help you when you think to yourself -'S$#@ I only have this small amount of time to get my render finshed'-
Complex scenes will require much higher subdivisions & pre-filtering as you would expect.

Hope this helps

[Bruce Hart]

Thanks 3DMK,
I tried the LC in primary and seconday bounce, and as you say the solution can become a bit oversmoothed if the value is too high, but a good timesaver for some scenes. I'll have to experiment with different subdivision values.

...and Peter - I've seen your beautiful work. If you're not using pre filter by now, you seem to be getting along just fine without it.

Cheers