Author Topic: Can you include/exclude alpha in the same render?  (Read 127 times)

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Offline AdamAnt

Can you include/exclude alpha in the same render?
« on: February 23, 2021, 02:52:25 am »
Hey guys

I need to render my shot with the background, and without the background..is there a way to do this with render layers or something?
Or do I have to add to outputs to the render que (with and without alpha checked?).. because i have trying to to this.. but im getting render errors when I do this...

and additionally, is there a way to get a black/white matte from the render passes? So that my object is white, and the rest black?
oh and finally.... what render passes do I need to check to get a composite view without the denoising applied? I know RGB is the only one that has the denoising...but I also need the 'final' picture without...so I can tune/blend the denoising myself...

thanks!

thanks!
« Last Edit: February 23, 2021, 02:55:15 am by AdamAnt »

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Re: Can you include/exclude alpha in the same render?
« Reply #1 on: February 23, 2021, 09:45:29 pm »

Hello AdamAnt

Put the top parent node of the scene tree to a render layer. That will give you a) the entire render with a transparent background (so you can toggle off alpha in render settings) and b) the render layer file is not denoised. Also you can check every render pass and look, what’s useful for your post processes like the common ones, clown, diffuse, etc. You can use the occlusion render pass or render your own, if you need more control.

Hope that helps a bit


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Offline TGS808

Re: Can you include/exclude alpha in the same render?
« Reply #2 on: February 24, 2021, 10:29:01 am »
is there a way to get a black/white matte from the render passes? So that my object is white, and the rest black?

You don't need to use render passes for this. Apply a flat white material to the object(s) in your scene. Set your environment background color to black. This will render a matte quickly.

Online INNEO_MWo

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Re: Can you include/exclude alpha in the same render?
« Reply #3 on: February 24, 2021, 01:14:41 pm »
A clown pass has a black background. So you can quickly select this, invert selection and fill with white on another layer. No need for extra effort. The black background with flat white parts may worth when it comes to animations and post workflows.


There are many useful techniques depending on the needs. But can be solved with KeyShot.

Offline TGS808

Re: Can you include/exclude alpha in the same render?
« Reply #4 on: February 24, 2021, 01:28:00 pm »
A clown pass has a black background. So you can quickly select this, invert selection and fill with white on another layer. No need for extra effort. The black background with flat white parts may worth when it comes to animations and post workflows.

There are many useful techniques depending on the needs. But can be solved with KeyShot.

There's not really any extra effort. It takes minutes. It's more than worth it if you have DOF in the scene. Personally, I'm not a fan of selections from the clown pass and never use them. There's too great a chance for fringing on the edges where two colors meet which makes for imperfect selections.

Offline mattjgerard

Re: Can you include/exclude alpha in the same render?
« Reply #5 on: February 25, 2021, 05:52:16 am »
is there a way to get a black/white matte from the render passes? So that my object is white, and the rest black?

You don't need to use render passes for this. Apply a flat white material to the object(s) in your scene. Set your environment background color to black. This will render a matte quickly.

Multimaterials and studios make this super easy to setup and retain your original setup as well