Before you can start using Atoms in your 3D application, you have to initialize your scene.
Some tools (i.e. Atoms UI) require your scene to be initialized, in case you haven't done that before opening such tools you will be prompted a dialog asking if you want to intialize it.
Alternatively you can initialize your scene manually via the shelf or the Atoms Menu: Atoms > Scene > Init Scene.
When a scene is initialized one or more nodes (depending on which 3D application you're working with) will be created.
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