Compositing w/ Render Layers 2.8 Instructions

[Cory Petkovsek]

Terminology:

Scene Layers -> Collections, found in the top right outliner.

Render Layers -> View layers, found in the very top right corner of your screen above the outliner.

Instructions:

1. Check Render settings, Film, Transparent (so objects render with alpha), and Transparent Glass since there is a glass in this scene. 
2. Make 4 Collections: Orb, Other objects, Backdrop, Lights/camera and move the objects into each. (Reuse the existing).
3. Make 3 Render Layers: Orb, Backdrop, Other objects render layers. (Reuse the existing).
4. Change to the Backdrop layer.
5. Right-click the Orb collection, go to View Layer, select Set Indirect Only. The orb disappears, but the shadow remains on the backdrop. If you don’t see this, go back over the instructions. This only works in Cycles, currently.
6. Repeat for the Other objects collection. Now you have a backdrop with light and shadows only.
7. Change to the Orb layer.
8. Uncheck (exclude) the Other objects and Backdrop collections. Leave the Orb and lights as is. Now you have an orb that is lit, on an alpha background.
9. Change to the Other objects layer.
10. Uncheck (exclude) the Orb and Backdrop collections. You have lit objects on an alpha background.
11. Render. In the render result you should have 3 layers exactly as described in #6, #8 and #10.
12. Switch to the Compositor and enable Use Nodes.
13. Add 3 Render Layer nodes and set them to Backdrop, Orb, Other objects.
14. Add a Color, Alpha Over node and connect Backdrop and Orb.
15. Add a second Alpha Over node and connect the output of the first, plus the Other objects. Connect that to the final Composite output note.
16. Render again and now you have four layers: The 3 described in #11, as well as a composite layer that should look as if you had rendered everything in one layer.

[Kent Trammell]

Thanks for taking the time to translate the 2.7x terminology + workflow to 2.8 @tinmanjuggernaut ! 🙇

[maxwildchild]

Thnx so much! Really helped me 

[Ukko-Pekka Kuivalainen]

I have the whole scene split up in separe view layers but would like to view the whole scene in 3d viewport. Do I just toggle the Collections on and off and hope I remembered to toggle the correct ones each time I render the scene again? Is there a better way to do that? Can I view multiple view layers at once in the viewport?

[spikeyxxx]

@ukkis what I would do is make another View Layer with all Collections enabled and use that to view the whole scene in the viewport and only render all the other layers by un-checking Use for Rendering for that View Layer:

[Christian Pohrer]

Thanks you so much. My only problem is that when i go to the composite layer Blender only shows me only the backdrop layer: 

Download_my_Blender_file

[spikeyxxx]

Hi @pohrerhub ,

there are two things missing: an  Output > Viewer Node and the Backdrop needs to be enabled (I didn’t do any rendering, so the Bacdrop is just black here):

[Christian Pohrer]

Hi @spikeyxxx 

It still renders just the backdrop. 

The other layers work perfectly:

Do you have any other ideas? 

[spikeyxxx]

@pohrerhub I think you have the order mixed up; the ‘background’ goes into the top socket of the Alpha Over:

I must admit that I can never remember this and always switch them untill it works 🙂

[Christian Pohrer]

thank youuu that worked

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