Does ARKit ever automatically update or "detect"/add a pure ARAnchor by itself? (Like how it generates ARPlaneAnchors?)

Question

What is the point of a "pure" ARAnchor (that isn't an ARPlaneAnchor)?

Does ARKit ever automatically update/track or add/detect a pure ARAnchor? (Like how it does with ARPlaneAnchor?)

Why would anyone want to add a custom ARAnchor to ARKit, if they are not being tracked?

Can a pure ARAnchor ever be automatically "upgraded" to an ARPlaneAnchor by ARKit?

Answer 1

The main reason why you might use ARAnchor.....

1. ARAnchor is suitable for non-SceneKit engine (SpriteKit, Metal, etc), for SceneKit it is the same (since ARKit derived from SceneKit and has the same world coordinate)

2. If you're using ARSKView, you need a way to reference positions / orientations in 3D (real-world) space, because SpriteKit isn't 3D. You need ARAnchor to keep track of positions in 3D so that they can get mapped into 2D.

3. If you're building your own non-SceneKit engine with Metal (or GL)... that's not a 3D scene description API — it's a GPU programming API — so it doesn't really have a notion of world space. You can use ARAnchor as a bridge between ARKit's notion of world space and whatever you build.

What's the difference between using ARAnchor to insert a node and directly insert a node?