2Sided VS Double Sided

[Morne]

Hi all

In the documentation it states:
"Note that the Secondary rays bias affects only things like GI, reflections etc. In order to render the scene properly, the material assigned to the box has its 2-sided option checked."

Is this the same as the double sided option in the vraymtl options?
"Double-sided - if this is true, V-Ray will flip the normal for back-facing surfaces with this material. Otherwise, the lighting on the "outer" side of the material will be computed always."

Just want to make sure that 2sided and double sided is the same thing here

[svetlozar.draganov]

In this case yes, double-sided and 2-sided means the same thing.
The idea is that the surface should have the same shader-properties from both sides since a part of the camera rays hit the front of the surface and the other part hit the back side.
If both sided have different properties artifacts will appear.

[Morne]

What's the cons of leaving secondary rays bias permanently on 0.001?

[svetlozar.draganov]

There aren't any cons with such low value as far as I know.
If you are using a greater value like 1.0 for example secondary rays calculation won't be very accurate for the finer details in the scene but 0.001 value is too small to notice any differences.