What is the reason the hand-tracking joints have these axes? I'm trying to create a virtual hands model and that's a mess.

I’ve been having some issues removing anchors. I can add anchors with no issue. They will be there the next time I run the scene. I can also get updates when ARKit sends them. I can remove anchors, but not all the time. The method I’m using is to call removeAnchor() on the data provider. worldTracking.removeAnchor(forID: uuid) // Yes, I have also tried `removeAnchor(_ worldAnchor: WorldAnchor)` This works if there are more than one anchor in a scene. When I’m down to one remaining anchor, I can remove it. It seems to succeed (does not raise an error) but the next time I run the scene the removed anchor is back. This only happens when there is only one remaining anchor. do { // This always run, but it doesn't seem to "save" the removal when there is only one anchor left. try await worldTracking.removeAnchor(forID: uuid) } catch { // I have never seen this block fire! print("Failed to remove world anchor \(uuid) with error: \(error).") } I posted a video on my website if you want to see it happening. https://stepinto.vision/labs/lab-051-issues-with-world-tracking/ Here is the full code. Can you see if I’m doing something wrong? Is this a bug? struct Lab051: View { @State var session = ARKitSession() @State var worldTracking = WorldTrackingProvider() @State var worldAnchorEntities: [UUID: Entity] = [:] @State var placement = Entity() @State var subject : ModelEntity = { let subject = ModelEntity( mesh: .generateSphere(radius: 0.06), materials: [SimpleMaterial(color: .stepRed, isMetallic: false)]) subject.setPosition([0, 0, 0], relativeTo: nil) let collision = CollisionComponent(shapes: [.generateSphere(radius: 0.06)]) let input = InputTargetComponent() subject.components.set([collision, input]) return subject }() var body: some View { RealityView { content in guard let scene = try? await Entity(named: "WorldTracking", in: realityKitContentBundle) else { return } content.add(scene) if let placementEntity = scene.findEntity(named: "PlacementPreview") { placement = placementEntity } } update: { content in for (_, entity) in worldAnchorEntities { if !content.entities.contains(entity) { content.add(entity) } } } .modifier(DragGestureImproved()) .gesture(tapGesture) .task { try! await setupAndRunWorldTracking() } } var tapGesture: some Gesture { TapGesture() .targetedToAnyEntity() .onEnded { value in if value.entity.name == "PlacementPreview" { // If we tapped the placement preview cube, create an anchor Task { let anchor = WorldAnchor(originFromAnchorTransform: value.entity.transformMatrix(relativeTo: nil)) try await worldTracking.addAnchor(anchor) } } else { Task { // Get the UUID we stored on the entity let uuid = UUID(uuidString: value.entity.name) ?? UUID() do { try await worldTracking.removeAnchor(forID: uuid) } catch { print("Failed to remove world anchor \(uuid) with error: \(error).") } } } } } func setupAndRunWorldTracking() async throws { if WorldTrackingProvider.isSupported { do { try await session.run([worldTracking]) for await update in worldTracking.anchorUpdates { switch update.event { case .added: let subjectClone = subject.clone(recursive: true) subjectClone.isEnabled = true subjectClone.name = update.anchor.id.uuidString subjectClone.transform = Transform(matrix: update.anchor.originFromAnchorTransform) worldAnchorEntities[update.anchor.id] = subjectClone print("🟢 Anchor added \(update.anchor.id)") case .updated: guard let entity = worldAnchorEntities[update.anchor.id] else { print("No entity found to update for anchor \(update.anchor.id)") return } entity.transform = Transform(matrix: update.anchor.originFromAnchorTransform) print("🔵 Anchor updated \(update.anchor.id)") case .removed: worldAnchorEntities[update.anchor.id]?.removeFromParent() worldAnchorEntities.removeValue(forKey: update.anchor.id) print("🔴 Anchor removed \(update.anchor.id)") if let remainingAnchors = await worldTracking.allAnchors { print("Remaining Anchors: \(remainingAnchors.count)") } } } } catch { print("ARKit session error \(error)") } } } }

After upgrading to Xcode 16 my app, which utilizes imported project files from my iPad's Reality Composer app, now has two issues that I have found so far. I am using an ARView as a UIViewRepresentable with SwiftUI. (Prior to upgading to Xcode 16 everything worked well.) First, there are now several duplicate rcp_export.usdz resources in the "Copy Bundle Resources" build phase section. Even though each file is in a separate folder with a unique UUID, it was causing a compile error saying there are duplicate files. I was able to open the RC project folder and delete the older rcp_project versions which now allows the app to compile. I mention it as it may or may not be related to the second issue. Second, Xcode isn't generating the project code for rcproject, so when I call the RCProject.loadSceneAsync function I am getting an error that says "Cannot find 'RCProject' in scope"