C4D Multipass - Separate pass for material layer
  • I've posted this over on mograph (traitor!) but only because specific application questions like this haven't really been done over here much, is that something that's wanted over here? Or would people prefer to keep here more of a discussion place rather than a technical place?

    So I'm doing a multi-pass render in c4d, using object buffers and taking out different parts in order to have more control in post, as is the norm. 

    One of my materials is a foil, with shiny implanted bits. I've made this using a layer shader. 

    The base material is has a layer on top which is a form of noise used to create the areas I want to sparkle. 
    I would like to be able to send just these parts out in order to make them sparkle in post. Anybody know how I can send that out as a pass?

    I know I could turn of all the other materials and make the noise white and render it out then use that as a matte.. but I don't want to. There's lots of objects with this noise, tons of different renders and all of it could change a LOT so a pass would be brilliant.. Anybody got any good ideas?
  • Technical questions are more than welcome here. That's why we have the software areas.

    Regarding this specific question, have you tried any of the material passes? What channel is your "sparkle noise" in?

    Another option you might want to try is taking your object buffer to isolate the objects, then using the Threshold effect in After Effects.

    Could you post a still of your render so we have a little better reference to work from?
  • Yes, bring on the tech questions/requests! I think I understand what you're trying to do... trying come up with a solution here. A still would be a great help!
  • @conigs It's in the colour channel, but the thing is it's not the only thing that is.. Here's a render with all the other channels turned off, so it's just the colour one. The grey is a base texture and the white is a noise shader on top (I've turned off a few layers for clarity too).

    I could absolutely use threshold in after effects on each one, (though the final texture is a bit more complex) but I was just wondering if I could avoid that step.

    Maybe I'm going overboard with the multipass thing but it appeals to me to be able to dial down to each layer of a channel in post, especially of something that I think the client is gonna be funny about..

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    Intro_Timing and Movement.jpg 127K
  • This is actually the first time I've used multi-pass properly, and the first proper 3D project I've done really...

    So maybe I'm going over the top a bit, cos I really like it!
  • I'd make the noise a completely different colour to everything else (like full red) then use that as a colour matte in AE. There's a great book by Jeremy Birn that describes this process in a lot more detail.
  • Yeah that's what I was going to do initially but then I was wondering if I could do it as it's own pass, totally separate, just out of curiosity really.

    As it happens I ended up going for a sort of diffused, rough glossy look to make it more realistic and I didn't actually use this sort of look.. Still would like if you could dial down that far into the passes but I guess it would get complicated if you could..

    Thanks for the help, putting that book on my wishlist too @dan_hin ...
  • Yeah that's the sort of thing I want to see in future versions of Cinema, there's not really a quick way to set up multilayer (as in - completely separate plates) renders, or custom passes.

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