Distinguish between multiple tracked images at the same time? - swift

Question

I currently have a group of 5 reference images that my app is tracking. However, I want it to be able distinguish between the reference images (i.e. if the image is of image A, image B, or image C. Tracking real photos I print out on postcards).
Currently, my code is able to detect the image and put a plane (i.e. a simple rectangle) over it. However, my question is, is it possible to distinguish whether the app has detected a picture of picture A vs picture B? If so, how?
I know there's an option to use ML, but wanted to see if there were any easier options in SceneKit/ARKit that I haven't considered; especially since I'm using the exact image and not trying to have the app guess an object.
class ViewController: UIViewController, ARSCNViewDelegate {
#IBOutlet var sceneView: ARSCNView!
override func viewDidLoad() {
super.viewDidLoad()
sceneView.delegate = self
}
//MARK-: WHERE I CONFIGURE MY APP TO DETECT AN IMAGE
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
let configuration = ARImageTrackingConfiguration()
guard let trackedImages = ARReferenceImage.referenceImages(inGroupNamed: "Photos", bundle: Bundle.main) else {
print("No images available")
return
}
configuration.trackingImages = trackedImages
configuration.maximumNumberOfTrackedImages = 7
sceneView.session.run(configuration)
}
//MARK-: WHERE I PLACE A PLANE OVER THE DETECTED IMAGE
func renderer(_ renderer: SCNSceneRenderer, nodeFor anchor: ARAnchor) -> SCNNode? {
let node = SCNNode()
if let imageAnchor = anchor as? ARImageAnchor {
let plane = SCNPlane(width: imageAnchor.referenceImage.physicalSize.width, height: imageAnchor.referenceImage.physicalSize.height)
plane.firstMaterial?.diffuse.contents = UIColor(white: 1, alpha: 0.8)
let planeNode = SCNNode(geometry: plane)
planeNode.eulerAngles.x = -.pi / 2
node.addChildNode(planeNode)
}
return node
}
}

Answer 1

You can easily do it using such instance properties as referenceImage and name.
// The detected image referenced by the image anchor.
var referenceImage: ARReferenceImage { get }
and:
// A descriptive name for your reference image.
var name: String? { get set }
Here's how they look like in code:
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
guard let imageAnchor = anchor as? ARImageAnchor,
let _ = imageAnchor.referenceImage.name
else { return }
anchorsArray.append(imageAnchor)
if imageAnchor.referenceImage.name == "apple" {
print("Image with apple is successfully detected...")
}
}

Answer 2

As per Andy's solution, I used the code below, and used the variable imageName as a reference.
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
guard let imageAnchor = anchor as? ARImageAnchor else { return }
let referenceImage = imageAnchor.referenceImage
let imageName = referenceImage.name ?? "no name"
}