Exclude Object from Global Illumination?

[mbutler2]

Is there any way to exclude an object from global illumination?

For example, inside a big tube I have some objects and the camera. Unfortunately, the big tube around everything keeps the inside objects from being illuminated. So I'd like to exclude the tube from global illumination if possible.

[dotJack]

Can try adding a octane object tag and unticking Shadow Visibility?

The question itself is rather unclear, you could clarify it with some screenshots.

edit:
It's not perfect because you don't really have that much control over what the renderer uses and doesn't use for what it does because that's just how it works.

I'm also not sure you're really using the term Global Illumination correctly but I think here's what you're after.
(Shadow visiblity OFF)


(Shadow visiblity ON)

[mbutler2]

Sure, here's a screen shot of the rough mockup.

Its a tube of lava that the camera will fly through. I have rocks cloned along the tube. As you can see, the rocks showing on the outside get global illumination, so they're orange. But the rocks inside the tube are black because global illumination can't make it through the tube object.

So I was hoping to exclude the tube from global illumination in order to let the rocks inside be illuminated. Unchecking the "Shadow Visibility" in the octane tag doesn't help unfortunately.

Other things I've found:

As soon as the tube is long and skinny, it gets much darker inside. The large short tube in your very kind example, it allows much more light in.

Also, the Octane Sky doesn't seem to respond to Shadow Visibility in the same way as Octane Daylight. As youve shown above, Daylight is aware of shadow visibility. So are area lights. But I think HDRI Octane sky isn't.

[Rev]

Which render kernel are you using, direct light or path tracing? Direct light will not work well for things that need to receive light indirectly. Also Have you tried making your lava walls be the actual light source? Technically speaking if this was a realistic setup, the lava itself would be what is lighting the scene and otherwise if it were me, I'd look for ways to get the lights inside of the tube.

Try playing with the attached c4d file. It's super rough, but should give you an idea.
Should look like this