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This has gotta be a bug: exclusion selection for GI objects
Or I’m not using it right? (GI, standard render, R19)
If you have some HDRI (or anything really in the luma channel) on some objects – in my case planes and disks – and you use these for lighting a scene, you should be able to exclude or include specific “receiver” objects in the scene within the compositing tag. And this does work – until it doesn’t.
I haven’t been able to figure out why one “not seen by camera” softbox ( this is what I’ll call them) will successfully light one object but not another (as it should based on the composting tag on the softbox), but then a copy of that softbox that is set to light yet another object but not the first bunch , it ends up lighting up everything.
In trying to art direct a very reflecty shot, I’m ready to be fitted for a sports jacket with the sleeves in the back.
I’d understand if it didn’t work at all. But to have it work for some of the soft boxes and not others is just plain frustrating. -
2 Replies
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don’t have 19 here but in 20 I get the behaviour I expect, it can’t be turned off except at a global level – either the emitter contributes to GI yes/no or a receiver can receive yes/no – no inclusion/exclusion like with standard lights and that’s what I expect. Unchecking Seen By Camera should only make the object invisible but it should still contribute GI. Maybe someone knows better but I think GI (at least in Standard) behaves ‘real’ and you can’t pull the same tricks as you can without GI, I did a quick test with Redshift and I don’t see an easy way there either (but may be missing something). It’s definitely possible in Corona – not that that helps
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It worked for me initially too and then it didn’t. For objects where it always worked, it still does, but often new hidden but luminous objects light up everything even with an exclusion tag.
I thought perhaps I wasn’t using it right.
Normally we set up our “reflectors” or “bounce cards” and that’s it, but there’s so much reflecting stuff in this shot that the director is art directing it to the nth – ” I like that reflection there but not that one” even though its the same bounce card making both reflections.
At the moment we’ve had to do multiple renders with cards on in some passes and different cards on in other passes, and then generate masks to comp the multiples together. I tried using object buffers and doing multi passes but that didn’t work either.
We tried the argument that “if you did this in real life those are the reflections you would get.” But that backfired because the director said that’s why he wanted to use CGI and not shoot it, so he could have that kind of control.
Its just such a shame because it does work correctly for some of the “paired” luminous objects and lit objects, but not others. Very odd.
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