How to keep ARKit SCNNode in place

Question

Hey I'm trying to figure out. How to keep a simple node in place. As I walk around it in ARKit

Code:

 func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {

    if let planeAnchor = anchor as? ARPlaneAnchor {

    if planeDetected == false { // Bool only allows 1 plane to be added
            planeDetected = true
        self.addPlane(node: node, anchor: planeAnchor)
    }

    }
}

This adds the SCNNode

    func addPlane(node: SCNNode, anchor: ARPlaneAnchor) {

    // We add the anchor plane here

    let showDebugVisuals = Bool()
    let plane = Plane(anchor, showDebugVisuals)
    planes[anchor] = plane
    node.addChildNode(plane)



    // We add our custom SCNNode here 

    let scene = SCNScene(named: "art.scnassets/PlayerModel.scn")!
    let Body = scene.rootNode.childNode(withName: "Body", recursively: true)!

    Body.position = SCNVector3.positionFromTransform(anchor.transform)
    Body.movabilityHint = .movable
    wrapperNode.position = SCNVector3.positionFromTransform(anchor.transform)

    wrapperNode.addChildNode(Body)

    scnView.scene.rootNode.addChildNode(wrapperNode)

Ive tried adding a Plane/Anchor Node and putting the "Body" node in that but it still moves. I thought maybe it has something to do with the update function.

 func renderer(_ renderer: SCNSceneRenderer, didUpdate node: SCNNode, for anchor: ARAnchor) {
 }

Or most likely the position setting

wrapperNode.position = SCNVector3.positionFromTransform(anchor.transform)

Iv'e looked through every source / project file / video on the internet and nobody has a simple solution to this simple problem.

user_10002969 · Answer

To keep an SCNNode in place you can disable sceneView plane detection once you get the result you desired.

let configuration = ARWorldTrackingConfiguration(); configuration.planeDetection = [] self.sceneView.session.run(configuration)

The reason for this is that ARKit constantly reestimates the position of the detected plane resulting in your SCNNode moving around.

How to keep ARKit SCNNode in place

2 Answers