Of Multiple Node Systems and Render Layers

I’ve been playing with blender for nearly four years now. I JUST got into making things with the Node Editor. I think I have a good feel for how it works, but there’s a major problem I’ve run into.

I’m making a sea (well a sea of light), and there will be bubbles coming out of it. The sea requires a massive node system (Kirsch filters, defocus, etc). The bubbles require only a few. But I can’t figure out how to get more than one node system into the compositor. Is there a way to do that? Do I need to use Render layers? If so, could someone please help me figure it out?

I need one node tree for the sea, and another for the bubble, but they BOTH need to be there in the final image. Thank you all.

Each scene can have it’s own node system, I think.

You can use render layers to create different processing paths within a single node system as well. Perhaps having the terminator of each path end up as file output for later compositiing. Or end up as mix nodes for a final composite.

You can reference render layers from different scenes from another scene. So you can setup a scene just for the sky and another just for the sea. Then in another scene bring both of those render layers in and composite them together.

once clarification to Atom’s post: the Renderlayer brings in the pre-composite rendered scene, not the result of the composite from that scene. So if you composite in one scene and composite in a second, you can use the third scene only with the VSE to alphaover or mix the two.

You know. I know you guys are right. But I have no clue what you’re saying. I’m not a programmer, or anyone with great skills in computing languages. Everything I’ve learned about Blender I’ve learned through hard, hard experience.

So. . . .could you guys maybe explain in more dumb terms. Please? I don’t mean to insult your intelligence. I just learn things much slower.

Any node setup from another scene (not the current scene) will not be taken into account during post render action (when the scene has been rendered and Blender begins compositing your nodes chain setup) if you import a render layer from another scene into the current scene. Only the nodes chain setup in the current scene gets composited.

In VSE however, IFF (if and only if) you have “Do Sequence” AND “Do Composite” enabled then, the nodes chain setups from BOTH scenes will be composited as separate operations.

You import different scenes into Blender’s compositor via the little set of arrows on the lower left hand corner of any render layer node and select the desired scene from the popup menu that appears, then you can select a render layer from that scene via the normal process.

You import separate scenes into VSE via “Scene” strips.

You know what. Let me post the file tomorrow, and see if you guys can give me some suggestions. I think having a visual might help us all.

Basically, “render layers” are a mechanism that lets you select what is, and is not, going to be an input at a particular stage in the rendering pipeline. (The word “layer” is unfortunately very over-used in the Blender world.)

When faced with a complicated scene like that, I instinctively break down the task into several different steps, each one of which produces intermediate files that are subsequently used “downstream.” That is, I’m going to first produce the sea (files), then produce the bubbles (files), then as an entirely distinct third step, merge them.

This is from my book “Foundation Blender Compositing”, Chapter 10 Figure 1. The compositor can pull in any scene, via the Render Layer node, as it is rendered from the 3D view. It can also pull in images.

The sequencer can pull in any scene, but if Do Composite is enabled for that scene, it pulls in the Compositor output…otherwise it pulls in the 3D View render. Like the compositor, the sequencer can also pull in images directly.

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