Forcing specific scene elements to not receive light?

SnowSultan

I think I already know the answer to this, but it never hurts to check. Is it currently not possible to have a spotlight *not* cast light on certain objects in a scene? I know we can use Canvases to make renders of only specularity and such, but I was wondering if there's a way to set which items in a scene are illuminated by a certain light source. Using a Light Group canvas seems like the right idea, but that just renders the single light (whichever is set to a node) as normal.

Thanks in advance for any information.

 

Bonus question: Does turning off Render Quality force Iray to render longer or at a higher quality than having it on? I watched a Dreamlight tutorial where they had it turned off, and I'm waiting for a render right now with Render Quality off that is already looking better than one I had at Render Quality 3 and it's only 71% done. Thanks.

Oso3D

The only unrealistic tricks I've seen in Iray is ghostlights and my Fantom effect ( https://www.daz3d.com/oso-master-shader1-for-iray )

Granted, Fantom is ... not what you're talking about at all, but hey.

 

SnowSultan

Hehe, sneaking that product plug in there...   ;)   Got to say though, Blendy is amazing and anyone who is making any sort of hybrid human/creature should be using it. We need more alpha maps for that thing.

Oso3D

Thank you!

Yeah, I need to use Blendy in a future product... mmm.

 

Zilvergrafix

SnowSultan said:

 

Bonus question: Does turning off Render Quality force Iray to render longer or at a higher quality than having it on? I watched a Dreamlight tutorial where they had it turned off, and I'm waiting for a render right now with Render Quality off that is already looking better than one I had at Render Quality 3 and it's only 71% done. Thanks.

from my experiencie and not being savvy with spec techs...YES.

but beware of artifacts (white pixels randomly) with Render Quality being OFF

Zilvergrafix

SnowSultan said:

I think I already know the answer to this, but it never hurts to check. Is it currently not possible to have a spotlight *not* cast light on certain objects in a scene? I know we can use Canvases to make renders of only specularity and such, but I was wondering if there's a way to set which items in a scene are illuminated by a certain light source. Using a Light Group canvas seems like the right idea, but that just renders the single light (whichever is set to a node) as normal.

Thanks in advance for any information

Render Passes, even Professionals uses that technique, why not?, + your mastery in Photoshop would be piece of cake such task!

I think can be doable with a plugin not created yet. SimTenero, Ncist where are you when needed?

SnowSultan

Thanks Zilver, I know I can render multiple times and paint in lighting with layer masks but was just hoping for an easier way.  After 20 years of doing this, I really want this year to be the one where I find a way to make more pictures more often and not have to render 30 masks and 4 full images to be combined in Photoshop for something that you could probably get done in a half hour.   ;)

Dave63

 You could try light path expressions canvases excluding surfaces to be illuminated( there is an operator/phrase structure for that). Somewhat complicated but more powerful than light groups canvases. 

 

SnowSultan

I thought of that too, but couldn't really find any sort of basic guide when I looked a while ago. It's ok, was just curious if I was missing something obvious. Thanks to everyone for the suggestions.

fred9803

I remember when I used to use Vue it was easy to set lights to affect specific objects only. Add this to the wishlist for the next version of DS.

Linwelly

Try giving it a geoshell with dark matter shader by Marshian turned to very low opacity?

I should try that myself at some point