Inserted models appear bigger than expected and on the back of camera

Question

Here is the properties of model that appears fine.

And here is the properties of model that has problems and appears bigger and above the camera view:

Here is my code to insert the model:

func updateUIView(_ uiView: ARView, context: Context) {
    // My Custom Class
    guard let model = modelConfirmedForPlacement else { return } 

    if let modelEntity = model.modelEntity {
        print("Adding model to scene: \(model.modelName)")
        let anchorEntity = AnchorEntity(plane: .any)
        let readyModelEntity = modelEntity.clone(recursive: true)
        //Add Gestures Support for Model
        readyModelEntity.generateCollisionShapes(recursive: true)
        anchorEntity.addChild(readyModelEntity)
        uiView.scene.addAnchor(anchorEntity)
        // Install Gestures
        uiView.installGestures([.all], for: readyModelEntity)
    } else {
        print("Unable to load modelEntity for: \(model.modelName)")
    }

    DispatchQueue.main.async {
        modelConfirmedForPlacement = nil
    }
}

Answer 1

Working units of RealityKit and SceneKit are meters, but default working units of some 3D apps are centimeters. Your metrics show the size of a huge RealityKit model's bounding box:

SIMD<Float>(x: 54.915, y: 45.507, z: 28.351)

To assign a new scale for an anchor entity or for a model entity (100...200 times smaller) use this:

let anchorEntity = AnchorEntity()
anchorEntity.scale = [1, 1, 1] * 0.01

To control model's position you must take into consideration a location of model's pivot point. Usually you can do it in 3D authoring app (like Maya or Blender) – a position of pivot point should be at a bottom of a model. In case you can't change pivot's position in 3D authoring app, just move a model's corresponding anchor:

anchorEntity.position.y = -0.5

...or if you want to move a model entity use children's deep hierarchy to get to it:

print(modelEntity)

modelEntity.children[0]..........children[0].position.y = -0.5