iOS ARKit: Why Are Saturn's Rings Clipped in AR View but Fully Visible in SceneKit Preview?

Below is one likely explanation and approach to try:

What's Likely Happening

Even though SceneKit’s preview shows the full rings, RealityKit (which you’re using in your AR app) may be “clipping” parts of your model when its automatically computed bounds or pivot don’t include the full extent of the rings. In other words, if the USDZ’s node hierarchy or collision bounds aren’t centered or large enough to cover the rings, then the AR view may end up “cutting” that geometry.

What You Can Do

• Check the Model’s Pivot and Bounds:
  When you load a USDZ file, RealityKit computes a default collision shape and bounding volume. If the rings extend beyond that volume, parts of the model might not be rendered in AR. Open your USDZ file in your 3D modeling tool or in Xcode’s preview editor and verify its pivot. If needed, re-center or offset the model so that the rings fall within the intended bounds.

• Generate Collision Shapes Manually:
  Instead of relying on the default collision shape, you can generate or supply one that fully encloses your Saturn model. For example, try generating collision shapes recursively:

  SWIFTCopied
  bodyEntity.generateCollisionShapes(recursive: true)

  This can help RealityKit understand the full extents of your model.

• Check Material Settings (Double-Sided Geometry):
  Although less likely if the central sphere is visible, also verify that the ring geometry is not set to a one‑sided material by mistake. In USDZ files, if a material is single‑sided, it might not render properly when viewed from certain angles.

Summary

Because the SceneKit preview and the AR app can treat model bounds differently, re-centering your model’s pivot or explicitly generating a collision shape that encloses the full model (rings and all) can resolve the clipping. Also, double‑check the material settings in your USDZ so that the ring geometry is correctly rendered.

Give these approaches a try and see if the rings display fully in your AR view.