Secondary rays bias gretaer than 0 - Any drawback ?

V-Ray V-Ray Common Render Theory
1

I was wondering if there was a drawback to always put 0,001 for the value of the Secondary rays bias (instead of 0) I understand that the GI solution is not “perfectly” accurate with this parameter, bet when it’s not barely visible, what’s the problem ?

Any drawback in term of quality of your solution, render times, or other issues?

2

sometimes it messes with your direct light shadows.

3

The problem would be if the offset is large enough to skip some surface in the rendering and cause incorrect shadows. For example, if you have a room enclosed with 1-surface walls only (no thickness), the ray bias might cause the rays to jump outside the room near corners producing bright edges.

Best regards,
Vlado

4

Ok, I understand. Thanks for the help

Hopefully, all my projects are modelled “volumetrically” but it may happen when importing models from crappy soft :wink:

5

occasionally this happens

Dear all,

I occasionally get rendering with rays peeking thru my model even with
0.0 secondary ray bias … is it due to the fact that my models may be intersecting each other? Turning on the check sample visiblity don’t seem
to help … if I am correct then it would be a modeling problem … how can
I achieve a correct modeling tech. which is spoken here? I have always
modelled using minimum surface possible.

best regards,
Victor NSY