Light Cache best settings

[lucabassan]

Hi to all,

I'd like hot to know find right settings for Light Cache on Arch Interior Renderings.

I mean, right Subdivisions and Sample Size values.

 

 

Is there a common way among V-Ray users to find right values?

tnx!

[salvador]

Turn on "Use LC for glossy rays". Speeds up your render a bit.

[Bruce Hart]

Hey Buddhabas,

if you set the filter option in the bottom right of that dialog box to none (for diagnostics), you will then see the size of each lightcache "facet" in relation to the geometry, and also the contrast in colour of neighboring facets. Say you turned the subdivisions down low to 100 - you would then see a very clear contrast difference between each cell. This is because there are not enough calculations (subdivs) being done per cell. The filter option turned on does its best to blend these cells together, but if subdivs are too low, you will of course get GI blotches. If your Sample Size is too big, may loose shadow contact detail, and your 2000 subdivs wont be effective. You have it larger than the default of .01

[salvador]

Bruce, the default is 0.02, but you are right, 0.01 works better.

[RyderSK]

It's personally not really worth adjusting the default size. The detail is by then already very good, but it's LC detail so it won't matter that much to final render clarity (as opposed to brute force detail or DE bounce in IR if used). By using higher value you can sort out light leaks (at toll in accuracy, as mentioned by Jim, to point of complete contact shadow diminishing), and oppositely, going too low can turn out to be light-leak prone, but it's nonetheless best to solve that with Retrace Threshold.

 

Subdivs for final quality still are ok anywhere between 2000 and 3000.

 

Vray manual and its examples describe all the features quite good.

[lucabassan]

@Salvador Jimenez: tnx! I know what means this option Anyway: I use 0,01 for final and 0,02 for preview render.

 

@Bruce Hart: tnx! pls can you explain (maybe with an image) what is "noise" on Light Cache?

 

@Juraj Talcik: tnx, I understood that Light Cache is so fast to calculate. So, also 2500-3000 subs don't scare me so much

 

Anyway, to all:

 

new question:

how Light Cache (his rays) works on these 2 situations?

 

- Light Cache only for primary bounce (none on secondary)

- Light Cache both primary and secondary bounce.

 

tnx!

Edited February 19, 2014 by lucabassan

[Bruce Hart]

Hi again - some examples here:

http://www.vray.com/vray_for_3ds_max/manual/vray_for_3ds_max_light_cache_examples.shtml

[lucabassan]

So noise means near cells with high intensity difference from them (where should not be so). Hence we must adjust various LC values to uniform more possible them. Right?

Using pre-filter and filter I have to smooth them more possible.Right?

Thanks

Edited February 19, 2014 by lucabassan