Resetting ARKit coordinates

Question

I have a simple question. If I wanted to start a game and place the board right in front of me:

gameBoard!.position = SCNVector3(0, 0, -0.6)

This works until I leave the game and come back again. Can I show the game board in exact same position in front of camera or 0.6m in front of me? I might have physically moved to another position.

You need to place the gameBoard 0.6m from where the camera is looking. Either reset the camera, or calculate the position of the board based on the camera's position. — allenh, Jul 14 '17 at 14:41
@AllenHumphreys My app freezes when this happens. Have you seen any documentation for this? — Jches, Jul 14 '17 at 19:05
My comment was based on working with SceneKit, but my assumption is that ARKit has a notion of a camera very similar to SceneKit. — allenh, Jul 14 '17 at 19:06
@AllenHumphreys can you give me a sample code of how to reset camera or position? — Lim Thye Chean, Jul 16 '17 at 09:28

score 9 · Accepted Answer · edited Sep 02 '18 at 14:19

9

If you want to reset you ARSession, you have to pause, remove all nodes and rerun your session by resetting tracking and removing anchors.

I made a reset button that does it whenever i want to reset:

@IBAction func reset(_ sender: Any) {

    sceneView.session.pause()
    sceneView.scene.rootNode.enumerateChildNodes { (node, stop) in
        node.removeFromParentNode()
    }
    sceneView.session.run(configuration, options: [.resetTracking, .removeExistingAnchors])
}

Or put it in your session was interrupted function!

edited Sep 02 '18 at 14:19

Andy Jazz

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answered Jul 19 '17 at 14:45

slimboy

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This seems to work fine. I put the reset in UIApplicationWillEnterForeground notification though, so every time the user comes back it will reset the game board position. – Lim Thye Chean Jul 20 '17 at 01:59

score 2 · Answer 2 · answered Feb 01 '18 at 13:45

This should be possible using the option resetTracking when you call run on your ARSession again.

Example:

if let configuration = sceneView.session.configuration {
    sceneView.session.run(configuration,
                          options: .resetTracking)
}

score 1 · Answer 3 · edited Jul 18 '17 at 01:41

1

"This works until I leave the game and come back again."

You can't track camera position in the background. Whenever your app goes to the background and camera turns off, you're losing your position, and sessionWasInterrupted(_:) will be called.

A session is interrupted when it fails to receive camera or motion sensing data. Session interruptions occur whenever camera capture is not available—for example, when your app is in the background or there are multiple foreground apps—or when the device is too busy to process motion sensor data.

edited Jul 18 '17 at 01:41

rmaddy

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answered Jul 17 '17 at 15:11

Vasilii Muravev

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how do you reset the camera? – slimboy Jul 19 '17 at 14:14
@slimboy What do you mean? Camera resets automatically, after app returns from the background. – Vasilii Muravev Jul 19 '17 at 14:17

score 1 · Answer 4 · answered Apr 09 '19 at 18:34

To reset ARSession in ARKit framework is quite easy:

class ViewController: UIViewController, ARSCNViewDelegate, ARSessionDelegate {

    @IBOutlet var arView: ARSCNView!
    @IBOutlet weak var sessionInfoLabel: UILabel!

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        let configuration = ARWorldTrackingConfiguration()
        configuration.planeDetection = [.horizontal, .vertical]
        arView.session.run(configuration)
        arView.session.delegate = self
    }
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        arView.session.pause()
    }
    func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
        guard let planeAnchor = anchor as? ARPlaneAnchor else { 
            return 
        }
        let plane = Plane(anchor: planeAnchor, in: arView)
        node.addChildNode(plane)
    }
    func sessionInterruptionEnded(_ session: ARSession) {
        resetSessionTracking()
        sessionInfoLabel.text = "ARSession's interruption has ended" 
    }
    private func resetSessionTracking() {
        let config = ARWorldTrackingConfiguration()
        config.planeDetection = [.vertical, .horizontal]
        arView.scene.rootNode.enumerateChildNodes { (childNode, _) in
            childNode.removeFromParentNode()
        }
        arView.session.run(config, options: [.removeExistingAnchors, 
                                             .resetTracking, ])
    }
}

Hope this helps.

Resetting ARKit coordinates

4 Answers4

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