Using Multiple AR Image Anchors to display dynamic 3D Overlay - ios

Question

I'm working on a project wherein we have to detect a certain number of custom QR codes (as ARImageAnchors) and then using the position of these anchors to dynamically display a 3D overlay. To be exact, we are planning to dynamically display a 3D model of human anatomy over the anchors which will be placed on a mannequin. For example, the mannequin we are placing the QR codes on is smaller or bigger than the default size of the 3D model, we would like it to adapt based on the distances between the images. Below is the sample code I'm thinking of working off from (source: https://www.appcoda.com/arkit-image-recognition/).
import UIKit
import ARKit
class ViewController: UIViewController {
#IBOutlet weak var sceneView: ARSCNView!
#IBOutlet weak var label: UILabel!
let fadeDuration: TimeInterval = 0.3
let rotateDuration: TimeInterval = 3
let waitDuration: TimeInterval = 0.5
lazy var fadeAndSpinAction: SCNAction = {
return .sequence([
.fadeIn(duration: fadeDuration),
.rotateBy(x: 0, y: 0, z: CGFloat.pi * 360 / 180, duration: rotateDuration),
.wait(duration: waitDuration),
.fadeOut(duration: fadeDuration)
])
}()
lazy var fadeAction: SCNAction = {
return .sequence([
.fadeOpacity(by: 0.8, duration: fadeDuration),
.wait(duration: waitDuration),
.fadeOut(duration: fadeDuration)
])
}()
lazy var treeNode: SCNNode = {
guard let scene = SCNScene(named: "tree.scn"),
let node = scene.rootNode.childNode(withName: "tree", recursively: false) else { return SCNNode() }
let scaleFactor = 0.005
node.scale = SCNVector3(scaleFactor, scaleFactor, scaleFactor)
node.eulerAngles.x = -.pi / 2
return node
}()
lazy var bookNode: SCNNode = {
guard let scene = SCNScene(named: "book.scn"),
let node = scene.rootNode.childNode(withName: "book", recursively: false) else { return SCNNode() }
let scaleFactor = 0.1
node.scale = SCNVector3(scaleFactor, scaleFactor, scaleFactor)
return node
}()
lazy var mountainNode: SCNNode = {
guard let scene = SCNScene(named: "mountain.scn"),
let node = scene.rootNode.childNode(withName: "mountain", recursively: false) else { return SCNNode() }
let scaleFactor = 0.25
node.scale = SCNVector3(scaleFactor, scaleFactor, scaleFactor)
node.eulerAngles.x += -.pi / 2
return node
}()
override func viewDidLoad() {
super.viewDidLoad()
sceneView.delegate = self
configureLighting()
}
func configureLighting() {
sceneView.autoenablesDefaultLighting = true
sceneView.automaticallyUpdatesLighting = true
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
resetTrackingConfiguration()
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
sceneView.session.pause()
}
#IBAction func resetButtonDidTouch(_ sender: UIBarButtonItem) {
resetTrackingConfiguration()
}
func resetTrackingConfiguration() {
guard let referenceImages = ARReferenceImage.referenceImages(inGroupNamed: "AR Resources", bundle: nil) else { return }
let configuration = ARWorldTrackingConfiguration()
configuration.detectionImages = referenceImages
let options: ARSession.RunOptions = [.resetTracking, .removeExistingAnchors]
sceneView.session.run(configuration, options: options)
label.text = "Move camera around to detect images"
}
}
extension ViewController: ARSCNViewDelegate {
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
DispatchQueue.main.async {
guard let imageAnchor = anchor as? ARImageAnchor,
let imageName = imageAnchor.referenceImage.name else { return }
// TODO: Comment out code
// let planeNode = self.getPlaneNode(withReferenceImage: imageAnchor.referenceImage)
// planeNode.opacity = 0.0
// planeNode.eulerAngles.x = -.pi / 2
// planeNode.runAction(self.fadeAction)
// node.addChildNode(planeNode)
// TODO: Overlay 3D Object
let overlayNode = self.getNode(withImageName: imageName)
overlayNode.opacity = 0
overlayNode.position.y = 0.2
overlayNode.runAction(self.fadeAndSpinAction)
node.addChildNode(overlayNode)
self.label.text = "Image detected: \"\(imageName)\""
}
}
func getPlaneNode(withReferenceImage image: ARReferenceImage) -> SCNNode {
let plane = SCNPlane(width: image.physicalSize.width,
height: image.physicalSize.height)
let node = SCNNode(geometry: plane)
return node
}
func getNode(withImageName name: String) -> SCNNode {
var node = SCNNode()
switch name {
case "Book":
node = bookNode
case "Snow Mountain":
node = mountainNode
case "Trees In the Dark":
node = treeNode
default:
break
}
return node
}
}
I know that the 3D overlay is displayed in the renderer function above, but it is only displaying on top of a single detected image anchor. Now my question is, is it possible to reference multiple ARImage anchors to dynamically display a single 3D model?
Being a novice in ARKit and Swift in general, I'm not sure how to go about this problem yet. I'm hoping someone might have an idea of how to work around this and point me to the right direction. Any help will be greatly appreciated!
Thanks in advance!