Should turning on GI affect what I see on the VrayLighting render element?

[irwit]

Hi all

Quick question I just need to sanity check.

I'm using Vray 3.1, max 2015, windows 7.

I create a teapot on a floor scene with an area light above. vray standard material. Create a vraylighting render element.

If I press render my lighting pass has x value on the top.

If I now turn on GI, brute force and light cache, and re-render, the lighting pass gets darker.

This shouldn't happen right? I've tested on a few machines and it keeps happening ?

I can post test renders if needed but maybe this is correct ?

Any help would be much appreciated.

Many thanks

Will.

[vlado]

This is correct and happens because of multiple importance sampling where parts of a light's contribution is computed through GI, and parts through direct sampling.

You can disable MIS for light sources, but this will generally produce more noisy renders and increased render times.

It may be possible to modify V-Ray to work differently and deposit a light's first hit of indirect contribution to the lighting render element, but I haven't looked into it yet.

Best regards,
Vlado