Blender Layers vs Render Layers

Hi all

I am wanting to know Blenders Layers (The dots)
Separating the objects onto other layers

Does this provide a more stable render?

Or am I confusing Render Layers?
Where you configure a render layer to a bunch of layers
And another render layer for other layers?


For blender layers

For Render Layers

… these are the first I’ve found, but will hopefully be quite helpful.


Still not really explaining if the layers provide better stability while rendering
EG: move all objects onto 1 layer and render
vs separate multiple objects to other layers
such as having 10 objects that have approx 80,000 triangles each
would blender be more stable having 800,000 Triangles on 1 layer vs 80,000 triangles for each visible layer?

or try and separate objects with large triangles to separate layers
I am not referring to render layers…

I have been in a habit to keep objects onto many layers for thinking it will help reduce memory usage.

I would also like to add a sort of PSA Notice, Explanations of ‘Render Layers’

Render layers, is sometimes not helpful especially if lighting needs to interact with other layers… if your thinking I will exclude layers with high verts/tris to save memory cost etc… it wont work because lighting completely skips the objects

when you exclude layers in render layers your basically turning off that layer so casting a shadow onto that object will be nonexsistant. Of if an object is suppose to cast a shadow etc…

in most scenarios memory usage is actually higher compared to rendering the objects in 1 render layer!
because the renderlayers which do not exclude layers are also loading those objects into VRAM/MEMORY and have seen HWINFO show as more memory usage.

Render Layers is very tricky to have lighting show up correctly and often spend more time then should be necessary setting it up.
Keeping meshes and objects clean and try to be as efficient and conservative about sub surfacing objects… if your Hardware is not up to scratch for Big scenes.

I have often spent hours trying Render Layers for it to give the same output and still causes blender to crash.

I personally don’t find renderlayers ever speed anything up… It often means that parts of the screen have to be rendered twice - once on each layer.

What I often do use it for(which does speed up rendering) is… if you’ve got a scene with a still camera, you can pre-render out a background and maybe a foreground, and then set up the moving part of your scene with shadow catchers and maybe invisible shadow catchers.

An object or a light can be on several layers. Render layers are sets of layers. So, it is a way to define collections of objects influenced by collections of lights.
The goal is to mix results at compositing level. It is not to be more efficient in realism of render.

If you have a huge scene rendered at once or several scenes rendered and them composited, one choice or the other may be faster depending of what you try to accomplish.

There is no general rule. It is dependent of your resources, quality your try to reach, your compositing knowledge.
You are not supposed to render 2 times same objects for no benefit.
Renderlayers are not supposed to represent same things.

And basically, splitting of your final render is not limited to renderlayers. You can composite renderlayers of different scenes. And those scenes should not necessary be build under same blend file.

The gain in memory is supposed to happen when final blend file running is calling linked others files that are not directly loaded.

Thanks for your knowledgeable response.

Can you verify if layers them selves…
Not the renderlayers. But the layers.

Do splitting objects to layers provide blender a more manageable render?
To try and render scenes with heaps of triangles
Does splitting to seperate layers help at all?

That never was the goal. The system was created for first open movie project : Elephant dreams.
So, basically, Blender had to respond to the needs of the movie.
At that period, blender foundation did not have manpower to reach heaps of triangles for sequences of movie. And movie plot was made to avoid that.
What was possible was light linking of some properties of lamps.
Shadowing of objects or illumination from some lamps could be limited to objects sharing same layer.
But that was Blender Internal features. Gain was not made on polycount but on shadow quality.
Replacing a distant light source producing costly ray shadows by several close spots doing fast shadow mapping.

Except that, one goal of layers is to have a more manageable scene, blend file.
And the other one, is to have a more manageable compositing in combination of use of renderlayers.

If you only separate objects on several layers, you can hide some layers and work on only one.
But if you render them all at once, there is no reason to expect a benefit compared to a render of all objects put on same layer.

But if your scene can be split into a foreground, a middle ground and a background, you can create a renderlayer corresponding to each ground ; and composite them into an image that could be impossible to render as a unique renderlayer.

For example, it is not rare to render an ocean as separated objects.
Highest picks of waves of ocean object at foreground being able to mask boundary of ocean object of background masking horizon of sky texture.
But if you try to render a unique Ocean object of several km with a close-up on one wave, you may not have enough power to create such mesh.

So, for renderlayers the answer is : yes , that helps.
But for layers, the answer is : we did not really care and it will no longer matter. In 2.8, layers are replaced by collections.

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