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I have a question about the Geometry to Instance node.

I read in the online Blender manual that this node can be much faster than the join geometry node when the inputs are large geometries. Here is the link (it in the 'tip' text): Geometry to Instance Node

Now I'm wondering: if it can be so much faster, in which cases exactly would you use the regular "Join Geometry" node and why?

Why not just always just use the "Geometry to Instance Node" instead?

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The Join Geometry node joins the specified objects and outputs a single object.

If you use this node with two or more meshes, their indices are changed and all elements of all domains are treated as one object.

For example, if you have two cubes that have eight points with indices 0-7, you will end up with one object with 16 points, with all points renumbered from 0-15. For this reason, additional computing power is necessary.

So this node behaves like Join.

Of course you can join any geometry with Join Geometry. You can also mix instances with meshes and curves, for example, if you want to output all your objects to the Group Output.

Geometry to Instances, on the other hand, only creates a reference to an existing object, so that the elements it contains (points, edges, faces, etc.) always remain unchanged.

This also speeds up any further processing, because the mesh does not have to be recalculated each time.

However, you cannot edit the contained elements unless you use the Realize Instances node, which converts your instance back into an editable mesh.

So you can't say exactly when you should use which node, because it simply depends on your particular use case.

But basically:

  • Use Join Geometry whenever you want to combine several objects and process them as one object (for example, if you want to change all points of all joined objects afterwards).
  • Use Geometry to Instances if your objects do not require any further manipulation other than their transformation.
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  • $\begingroup$ Thanks a lot Stephan for this very clarifying answer! This is useful. Now the 'realize instances" node also makes sense suddenly. They could actually put your answer in the Blender manual. :-) $\endgroup$ Jul 9, 2023 at 15:50

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