Place image from Gallery on a Wall using ARKit - swift

I have a list of images coming from server and stored in gallery. I want to pick any image and place on live wall using ARKit and want to convert images into 3d images tp perform operation like zooming , moving image etc.
Can anybody please guide how can I create custom object in AR?

To detect vertical surfaces (e.g walls) in ARKit you need to firstly set up ARWorldTrackingConfiguration and then enable planeDetection within your app.
So under your Class Declaration you would create the following variables:
#IBOutlet var augmentedRealityView: ARSCNView!
let augmentedRealitySession = ARSession()
let configuration = ARWorldTrackingConfiguration()
And then initialise your ARSession and in ViewDidLoad for example e.g:
override func viewDidLoad() {
super.viewDidLoad()
//1. Set Up Our ARSession
augmentedRealityView.session = augmentedRealitySession
//2. Assign The ARSCNViewDelegate
augmentedRealityView.delegate = self
//3. Set Up Plane Detection
configuration.planeDetection = .vertical
//4. Run Our Configuration
augmentedRealitySession.run(configuration, options: [.resetTracking, .removeExistingAnchors])
}
Now that you are all set to detected vertical planes you need to hook into the following ARSCNViewDelegate Method:
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) { }
Which simply:
Tells the delegate that a SceneKit node corresponding to a new AR
anchor has been added to the scene.
In this method we are going to explicitly look for any ARPlaneAnchors which have been detected which provide us with:
Information about the position and orientation of a real-world flat
surface detected in a world-tracking AR session.
As such placing an SCNPlane onto a detected vertical plane is a simple as this:
//-------------------------
//MARK: - ARSCNViewDelegate
//-------------------------
extension ViewController: ARSCNViewDelegate{
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
//1. Check We Have Detected An ARPlaneAnchor
guard let planeAnchor = anchor as? ARPlaneAnchor else { return }
//2. Get The Size Of The ARPlaneAnchor
let width = CGFloat(planeAnchor.extent.x)
let height = CGFloat(planeAnchor.extent.z)
//3. Create An SCNPlane Which Matches The Size Of The ARPlaneAnchor
let imageHolder = SCNNode(geometry: SCNPlane(width: width, height: height))
//4. Rotate It
imageHolder.eulerAngles.x = -.pi/2
//5. Set It's Colour To Red
imageHolder.geometry?.firstMaterial?.diffuse.contents = UIColor.red
//4. Add It To Our Node & Thus The Hiearchy
node.addChildNode(imageHolder)
}
}
Applying This To Your Case:
In your case we need to do some additional work, as you want to be able to allow the user to apply an image to the vertical plane.
As such your best bet is to make the node you have just added a variable e.g.
class ViewController: UIViewController {
#IBOutlet var augmentedRealityView: ARSCNView!
let augmentedRealitySession = ARSession()
let configuration = ARWorldTrackingConfiguration()
var nodeWeCanChange: SCNNode?
}
As such your Delegate Callback might look like so:
//-------------------------
//MARK: - ARSCNViewDelegate
//-------------------------
extension ViewController: ARSCNViewDelegate{
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
//1. If We Havent Create Our Interactive Node Then Proceed
if nodeWeCanChange == nil{
//a. Check We Have Detected An ARPlaneAnchor
guard let planeAnchor = anchor as? ARPlaneAnchor else { return }
//b. Get The Size Of The ARPlaneAnchor
let width = CGFloat(planeAnchor.extent.x)
let height = CGFloat(planeAnchor.extent.z)
//c. Create An SCNPlane Which Matches The Size Of The ARPlaneAnchor
nodeWeCanChange = SCNNode(geometry: SCNPlane(width: width, height: height))
//d. Rotate It
nodeWeCanChange?.eulerAngles.x = -.pi/2
//e. Set It's Colour To Red
nodeWeCanChange?.geometry?.firstMaterial?.diffuse.contents = UIColor.red
//f. Add It To Our Node & Thus The Hiearchy
node.addChildNode(nodeWeCanChange!)
}
}
}
Now you have a reference to the nodeWeCanChange setting it's image at anytime is simple!
Each SCNGeometry has a set of Materials which are a:
A set of shading attributes that define the appearance of a geometry's
surface when rendered.
In our case we are looking for the materials diffuse property which is:
An object that manages the material’s diffuse response to lighting.
And then the contents property which are:
The visual contents of the material property—a color, image, or source
of animated content.
Obviously you need to handle the full logistics of this, however a very basic example might look like so assuming you stored your Images into an Array of UIImage e.g:
let imageGallery = [UIImage(named: "StackOverflow"), UIImage(named: "GitHub")]
I have created an IBAction which will change the image of our SCNNode's Geometry based on the tag of the UIButton pressed e.g:
/// Changes The Material Of Our SCNNode's Gemeotry To The Image Selected By The User
///
/// - Parameter sender: UIButton
#IBAction func changeNodesImage(_ sender: UIButton){
guard let imageToApply = imageGallery[sender.tag], let node = nodeWeCanChange else { return}
node.geometry?.firstMaterial?.diffuse.contents = imageToApply
}
This is more than enough to point you in the right direction... Hope it helps...

Related

Can I do ARKit "Continuous Image Tracking" in a World Tracking Configuration with RealityKit?

UPDATE: My premise that "continuous image tracking" is not possible out of the box with RealityKit ARViews was incorrect. All I needed to do was correctly create the AnchorEntity for the continuously tracked reference image.
The anchor entity needs to be created using the init(anchor: ARAnchor) initializer. (The init(world: SIMD3<Float>) initializer is correct for anchors stuck to the real world, but not ones that should track the reference image.)
Using ARKit and RealityKit with an ARWorldTrackingConfiguration, I am trying to do "continuous image tracking" (where the reference image is tracked each frame, and virtual objects can be anchored to it, appearing to be attached to and move with the reference image). Because reference images are only recognized once in world tracking (as opposed to ARImageTrackingConfiguration, where reference images are continuously tracked as long as they are in frame), this is not possible out of the box.
To get the same results in a world tracking configuration, I am anchoring virtual objects to the reference image in the session(_:didAdd:) delegate method, and using the session(_:didUpdate:) delegate method as an opportunity to remove the ARImageAnchor after each time it is identified. This causes the reference image to be re-recognized over and over, allowing virtual objects to be anchored to the image and appear to track it frame-to-frame.
In the example below, I am placing two ball markers to track the position of the reference image. First marker is placed only once, at the location where the reference image is initially detected. The other marker is re-positioned each time the reference image is re-detected, appearing to follow it.
This works. Virtual content tracks the reference image in the ARWorldTrackingConfiguration the same way it would in an image tracking config. But while the "animation" in ARImageTrackingConfiguration is very smooth, the animation in world tracking is much less smooth, more jumpy, as if it was running at 10 or 15 frames per second. (Actual FPS as reported by .showStatistics stays near 60 FPS in both configurations.)
I assume the difference in smoothness results from the time it takes ARKit to do the work of repeatedly re-recognizing and removing the reference image anchor on each didAdd/didUpdate cycle.
I would like to know if there is a better technique to get "continuous image tracking" in an ARWorldTrackingConfiguration, and/or if there is any way I can improve the code in the delegate methods to achieve this affect.
import ARKit
import RealityKit
class ViewController: UIViewController, ARSessionDelegate {
#IBOutlet var arView: ARView!
// originalImageAnchor is used to visualize the first-detected location of reference image
// currentImageAnchor should be continuously updated to match current position of ref image
var originalImageAnchor: AnchorEntity!
var currentImageAnchor: AnchorEntity!
let ballRadius: Float = 0.02
override func viewDidLoad() {
super.viewDidLoad()
guard let referenceImages = ARReferenceImage.referenceImages(inGroupNamed: "AR Resources",
bundle: nil) else { fatalError("Missing expected asset catalog resources.") }
arView.session.delegate = self
arView.automaticallyConfigureSession = false
arView.debugOptions = [.showStatistics]
arView.renderOptions = [.disableCameraGrain, .disableHDR, .disableMotionBlur,
.disableDepthOfField, .disableFaceOcclusions, .disablePersonOcclusion,
.disableGroundingShadows, .disableAREnvironmentLighting]
let configuration = ARWorldTrackingConfiguration()
configuration.detectionImages = referenceImages
configuration.maximumNumberOfTrackedImages = 1 // there is one ref image named "coaster_rb"
arView.session.run(configuration)
}
func session(_ session: ARSession, didAdd anchors: [ARAnchor]) {
guard let imageAnchor = anchors[0] as? ARImageAnchor else { return }
// Reference image detected. This will happen multiple times because
// we delete ARImageAnchor in session(_:didUpdate:)
if let imageName = imageAnchor.name, imageName == "coaster_rb" {
// If originalImageAnchor is nil, create an anchor and
// add a marker at initial position of reference image.
if originalImageAnchor == nil {
originalImageAnchor = AnchorEntity(world: imageAnchor.transform)
let originalImageMarker = generateBallMarker(radius: ballRadius, color: .systemPink)
originalImageMarker.position.y = ballRadius + (ballRadius * 2)
originalImageAnchor.addChild(originalImageMarker)
arView.scene.addAnchor(originalImageAnchor)
}
// If currentImageAnchor is nil, add an anchor and marker at reference image position
// If currentImageAnchor has already been added, adjust it's position to match ref image
if currentImageAnchor == nil {
currentImageAnchor = AnchorEntity(world: imageAnchor.transform)
let currentImageMarker = generateBallMarker(radius: ballRadius, color: .systemTeal)
currentImageMarker.position.y = ballRadius
currentImageAnchor.addChild(currentImageMarker)
arView.scene.addAnchor(currentImageAnchor)
} else {
currentImageAnchor.setTransformMatrix(imageAnchor.transform, relativeTo: nil)
}
}
}
func session(_ session: ARSession, didUpdate anchors: [ARAnchor]) {
guard let imageAnchor = anchors[0] as? ARImageAnchor else { return }
// Delete reference image anchor to allow for ongoing tracking as it moves
if let imageName = imageAnchor.name, imageName == "coaster_rb" {
arView.session.remove(anchor: anchors[0])
}
}
func generateBallMarker(radius: Float, color: UIColor) -> ModelEntity {
let ball = ModelEntity(mesh: .generateSphere(radius: radius),
materials: [SimpleMaterial(color: color, isMetallic: false)])
return ball
}
}
Continuous image tracking does work out of the box with RealityKit ARViews in world tracking configurations. A mistake in my original code lead me to think otherwise.
Incorrect anchor entity initialization (for what I was trying to accomplish):
currentImageAnchor = AnchorEntity(world: imageAnchor.transform)
Since I wanted to track the ARImageAnchor assigned to the matched reference image, I should have done it like this:
currentImageAnchor = AnchorEntity(anchor: imageAnchor)
The corrected example below places one virtual marker that is fixed to the reference image's initial position, and another that smoothly tracks the reference image in a world tracking configuration:
import ARKit
import RealityKit
class ViewController: UIViewController, ARSessionDelegate {
#IBOutlet var arView: ARView!
let ballRadius: Float = 0.02
override func viewDidLoad() {
super.viewDidLoad()
guard let referenceImages = ARReferenceImage.referenceImages(
inGroupNamed: "AR Resources", bundle: nil) else {
fatalError("Missing expected asset catalog resources.")
}
arView.session.delegate = self
arView.automaticallyConfigureSession = false
arView.debugOptions = [.showStatistics]
arView.renderOptions = [.disableCameraGrain, .disableHDR,
.disableMotionBlur, .disableDepthOfField,
.disableFaceOcclusions, .disablePersonOcclusion,
.disableGroundingShadows, .disableAREnvironmentLighting]
let configuration = ARWorldTrackingConfiguration()
configuration.detectionImages = referenceImages
configuration.maximumNumberOfTrackedImages = 1
arView.session.run(configuration)
}
func session(_ session: ARSession, didAdd anchors: [ARAnchor]) {
guard let imageAnchor = anchors[0] as? ARImageAnchor else { return }
if let imageName = imageAnchor.name, imageName == "target_image" {
// AnchorEntity(world: imageAnchor.transform) results in anchoring
// virtual content to the real world. Content anchored like this
// will remain in position even if the reference image moves.
let originalImageAnchor = AnchorEntity(world: imageAnchor.transform)
let originalImageMarker = makeBall(radius: ballRadius, color: .systemPink)
originalImageMarker.position.y = ballRadius + (ballRadius * 2)
originalImageAnchor.addChild(originalImageMarker)
arView.scene.addAnchor(originalImageAnchor)
// AnchorEntity(anchor: imageAnchor) results in anchoring
// virtual content to the ARImageAnchor that is attached to the
// reference image. Content anchored like this will appear
// stuck to the reference image.
let currentImageAnchor = AnchorEntity(anchor: imageAnchor)
let currentImageMarker = makeBall(radius: ballRadius, color: .systemTeal)
currentImageMarker.position.y = ballRadius
currentImageAnchor.addChild(currentImageMarker)
arView.scene.addAnchor(currentImageAnchor)
}
}
func makeBall(radius: Float, color: UIColor) -> ModelEntity {
let ball = ModelEntity(mesh: .generateSphere(radius: radius),
materials: [SimpleMaterial(color: color, isMetallic: false)])
return ball
}
}

ARKit detecting intersection between planes

I am using ARKit (with Scene Kit) and am trying to find a way to get the intersection between an ARReference image and a Horizontal ARPlaneDetection to display a 3D character on the surface directly in front of the detected image, e.g., Spawn inside the red circle see image below
At the moment I am able to get the character to spawn in front of the detected image, however, the character is floating in the air instead of standing on the surface.
let realWorldPositon = SCNVector3Make(anchor.transform.columns.3.x, anchor.transform.columns.3.y, anchor.transform.columns.3.z)
let hitTest = self.sceneView.scene.rootNode.hitTestWithSegment(from: self.sceneView.scene.rootNode.worldPosition, to: realWorldPositon, options: nil)
overlayNode.position = SCNVector3Make((hitTest.first?.worldCoordinates.x)!, 0, (hitTest.first?.worldCoordinates.z)!)
self.sceneView.scene.rootNode.addChildNode(overlayNode)
Any help on this would be greatly appreciated, thanks!
Example project
I think you were on the right lines using the hitTestWithSegment function to detect an intersection between the ARImageAnchor and the ARPlaneAnchor.
Rather than trying to explain each step of my attempt at an answer, I have provided code which is fully commented, so it should be fairly self explanatory.
My example works fairly well (although its certainly not perfect) and will definitely need some tweaking.
For example, you will need to look at determining more accurately the distance from the ARReferenceImage to the ARPlaneAnchor etc.
I can get the model (a Pokemon) to place at the correct level and fairly close to the front of the ARReferenceImage, although it will need tweaking.
Having said this, I think this will be a fairly good base for you to start refining the code and getting more accurate results.
Of note however, is that I have just enabled one ARPlaneAnchor to be detected (just for simplicities sake) and have assumed that you will be detecting a plane infront of your image marker.
I haven't taken into account rotation or anything like that. And of course, based on your proposed scenario; it also assumes your image would be on a desk or some other flat surface.
Anyway, here is my answer (hopefully it should be fairly self explanatory):
import UIKit
import ARKit
//-----------------------
//MARK: ARSCNViewDelegate
//-----------------------
extension ViewController: ARSCNViewDelegate{
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
//1. If We Have Detected Our ImageTarget Then Create A Plane To Visualize It
if let currentImageAnchor = anchor as? ARImageAnchor {
createReferenceImagePlaneForNode(currentImageAnchor, node: node)
allowTracking = true
}
//2. If We Have Detected A Horizontal Plane Then Create One
if let currentPlaneAnchor = anchor as? ARPlaneAnchor{
if planeNode == nil && !createdModel{ createReferencePlaneForNode(currentPlaneAnchor, node: node) }
}
}
func renderer(_ renderer: SCNSceneRenderer, didUpdate node: SCNNode, for anchor: ARAnchor) {
//1. Check To See Whether An ARPlaneAnchor Has Been Updated
guard let anchor = anchor as? ARPlaneAnchor,
//2. Check It Is Our PlaneNode
let existingPlane = planeNode,
//3. Get The Geometry Of The PlaneNode
let planeGeometry = existingPlane.geometry as? SCNPlane else { return }
//4. Adjust It's Size & Positions
planeGeometry.width = CGFloat(anchor.extent.x)
planeGeometry.height = CGFloat(anchor.extent.z)
planeNode?.position = SCNVector3Make(anchor.center.x, 0.01, anchor.center.z)
}
func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
//1. Detect The Intersection Of The ARPlaneAnchor & ARImageAncho
if allowTracking { detectIntersetionOfImageTarget() }
}
}
//---------------------------------------
//MARK: Model Generation & Identification
//---------------------------------------
extension ViewController {
/// Detects If We Have Intersected A Valid Image Target
func detectIntersetionOfImageTarget(){
//If We Havent Created Our Model Then Check To See If We Have Detected An Existing Plane
if !createdModel{
//a. Perform A HitTest On The Center Of The Screen For AnyExisting Planes
guard let planeHitTest = self.augmentedRealityView.hitTest(screenCenter, types: .existingPlaneUsingExtent).first,
let planeAnchor = planeHitTest.anchor as? ARPlaneAnchor else { return }
//b. Get The Transform Of The ARPlane Anchor
let x = planeAnchor.transform.columns.3.x
let y = planeAnchor.transform.columns.3.y
let z = planeAnchor.transform.columns.3.z
//b. Create The Anchors Vector
let anchorVector = SCNVector3(x,y, z)
//Perform Another HitTest From The ImageAnchor Vector To The Anchors Vector
if let _ = self.augmentedRealityView.scene.rootNode.hitTestWithSegment(from: imageAnchorVector, to: anchorVector, options: nil).first?.node {
//a. If We Havent Created The Model Then Place It As Soon As An Intersection Occures
if createdModel == false{
//b. Load The Model
loadModelAtVector(SCNVector3(imageAnchorVector.x, y, imageAnchorVector.z))
createdModel = true
planeNode?.removeFromParentNode()
}
}
}
}
}
class ViewController: UIViewController {
//1. Reference To Our ImageTarget Bundle
let AR_BUNDLE = "AR Resources"
//2. Vector To Store The Position Of Our Detected Image
var imageAnchorVector: SCNVector3!
//3. Variables To Allow Tracking & To Determine Whether Our Model Has Been Placed
var allowTracking = false
var createdModel = false
//4. Create A Reference To Our ARSCNView In Our Storyboard Which Displays The Camera Feed
#IBOutlet weak var augmentedRealityView: ARSCNView!
//5. Create Our ARWorld Tracking Configuration
let configuration = ARWorldTrackingConfiguration()
//6. Create Our Session
let augmentedRealitySession = ARSession()
//7. ARReference Images
lazy var staticReferenceImages: Set<ARReferenceImage> = {
let images = ARReferenceImage.referenceImages(inGroupNamed: AR_BUNDLE, bundle: nil)
return images!
}()
//8. Scrren Center Reference
var screenCenter: CGPoint!
//9. PlaneNode
var planeNode: SCNNode?
//--------------------
//MARK: View LifeCycle
//--------------------
override func viewDidLoad() {
super.viewDidLoad()
//1. Get Reference To The Center Of The Screen For RayCasting
DispatchQueue.main.async { self.screenCenter = CGPoint(x: self.view.bounds.width/2, y: self.view.bounds.height/2) }
//2. Setup Our ARSession
setupARSessionWithStaticImages()
}
override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() }
//---------------------------------
//MARK: ARImageAnchor Vizualization
//---------------------------------
/// Creates An SCNPlane For Visualizing The Detected ARImageAnchor
///
/// - Parameters:
/// - imageAnchor: ARImageAnchor
/// - node: SCNNode
func createReferenceImagePlaneForNode(_ imageAnchor: ARImageAnchor, node: SCNNode){
//1. Get The Targets Width & Height
let width = imageAnchor.referenceImage.physicalSize.width
let height = imageAnchor.referenceImage.physicalSize.height
//2. Create A Plane Geometry To Cover The ARImageAnchor
let planeNode = SCNNode()
let planeGeometry = SCNPlane(width: width, height: height)
planeGeometry.firstMaterial?.diffuse.contents = UIColor.white
planeNode.opacity = 0.5
planeNode.geometry = planeGeometry
//3. Rotate The PlaneNode To Horizontal
planeNode.eulerAngles.x = -.pi/2
//4. The Node Is Centered In The Anchor (0,0,0)
node.addChildNode(planeNode)
//5. Store The Vector Of The ARImageAnchor
imageAnchorVector = SCNVector3(imageAnchor.transform.columns.3.x, imageAnchor.transform.columns.3.y, imageAnchor.transform.columns.3.z)
let fadeOutAction = SCNAction.fadeOut(duration: 5)
planeNode.runAction(fadeOutAction)
}
//-------------------------
//MARK: Plane Visualization
//-------------------------
/// Creates An SCNPlane For Visualizing The Detected ARAnchor
///
/// - Parameters:
/// - imageAnchor: ARAnchor
/// - node: SCNNode
func createReferencePlaneForNode(_ anchor: ARPlaneAnchor, node: SCNNode){
//1. Get The Anchors Width & Height
let width = CGFloat(anchor.extent.x)
let height = CGFloat(anchor.extent.z)
//2. Create A Plane Geometry To Cover The ARImageAnchor
planeNode = SCNNode()
let planeGeometry = SCNPlane(width: width, height: height)
planeGeometry.firstMaterial?.diffuse.contents = UIColor.white
planeNode?.opacity = 0.5
planeNode?.geometry = planeGeometry
//3. Rotate The PlaneNode To Horizontal
planeNode?.eulerAngles.x = -.pi/2
//4. The Node Is Centered In The Anchor (0,0,0)
node.addChildNode(planeNode!)
}
//-------------------
//MARK: Model Loading
//-------------------
/// Loads Our Model Based On The Resulting Vector Of Our ARAnchor
///
/// - Parameter worldVector: SCNVector3
func loadModelAtVector(_ worldVector: SCNVector3) {
let modelPath = "ARModels.scnassets/Scatterbug.scn"
//1. Get The Reference To Our SCNScene & Get The Model Root Node
guard let model = SCNScene(named: modelPath),
let pokemonModel = model.rootNode.childNode(withName: "RootNode", recursively: false) else { return }
//2.Add It To Our SCNView
augmentedRealityView.scene.rootNode.addChildNode(pokemonModel)
//3. Scale The Scatterbug
pokemonModel.scale = SCNVector3(0.003, 0.003, 0.003)
pokemonModel.position = worldVector
augmentedRealityView.scene.rootNode.addChildNode(pokemonModel)
}
//---------------
//MARK: ARSession
//---------------
/// Sets Up The AR Session With Static Or Dynamic AEImages
func setupARSessionWithStaticImages(){
//1. Set Our Configuration
configuration.detectionImages = staticReferenceImages
configuration.planeDetection = .horizontal
//2. Run The Configuration
augmentedRealitySession.run(configuration, options: [.resetTracking, .removeExistingAnchors])
//3. Set The Session & Delegate
augmentedRealityView?.session = augmentedRealitySession
self.augmentedRealityView?.delegate = self
}
}
Hope it points you in the right direction...

Check whether the ARReferenceImage is no longer visible in the camera's view

I would like to check whether the ARReferenceImage is no longer visible in the camera's view. At the moment I can check if the image's node is in the camera's view, but this node is still visible in the camera's view when the ARReferenceImage is covered with another image or when the image is removed.
func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
guard let node = self.currentImageNode else { return }
if let pointOfView = sceneView.pointOfView {
let isVisible = sceneView.isNode(node, insideFrustumOf: pointOfView)
print("Is node visible: \(isVisible)")
}
}
So I need to check if the image is no longer visible instead of the image's node visibility. But I can't find out if this is possible. The first screenshot shows three boxes that are added when the image beneath is found. When the found image is covered (see screenshot 2) I would like to remove the boxes.
I managed to fix the problem! Used a little bit of Maybe1's code and his concept to solving the problem, but in a different way. The following line of code is still used to reactivate the image recognition.
// Delete anchor from the session to reactivate the image recognition
sceneView.session.remove(anchor: anchor)
Let me explain. First we need to add some variables.
// The scnNodeBarn variable will be the node to be added when the barn image is found. Add another scnNode when you have another image.
var scnNodeBarn: SCNNode = SCNNode()
// This variable holds the currently added scnNode (in this case scnNodeBarn when the barn image is found)
var currentNode: SCNNode? = nil
// This variable holds the UUID of the found Image Anchor that is used to add a scnNode
var currentARImageAnchorIdentifier: UUID?
// This variable is used to call a function when there is no new anchor added for 0.6 seconds
var timer: Timer!
The complete code with comments below.
/// - Tag: ARImageAnchor-Visualizing
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
guard let imageAnchor = anchor as? ARImageAnchor else { return }
let referenceImage = imageAnchor.referenceImage
// The following timer fires after 0.6 seconds, but everytime when there found an anchor the timer is stopped.
// So when there is no ARImageAnchor found the timer will be completed and the current scene node will be deleted and the variable will set to nil
DispatchQueue.main.async {
if(self.timer != nil){
self.timer.invalidate()
}
self.timer = Timer.scheduledTimer(timeInterval: 0.6 , target: self, selector: #selector(self.imageLost(_:)), userInfo: nil, repeats: false)
}
// Check if there is found a new image on the basis of the ARImageAnchorIdentifier, when found delete the current scene node and set the variable to nil
if(self.currentARImageAnchorIdentifier != imageAnchor.identifier &&
self.currentARImageAnchorIdentifier != nil
&& self.currentNode != nil){
//found new image
self.currentNode!.removeFromParentNode()
self.currentNode = nil
}
updateQueue.async {
//If currentNode is nil, there is currently no scene node
if(self.currentNode == nil){
switch referenceImage.name {
case "barn":
self.scnNodeBarn.transform = node.transform
self.sceneView.scene.rootNode.addChildNode(self.scnNodeBarn)
self.currentNode = self.scnNodeBarn
default: break
}
}
self.currentARImageAnchorIdentifier = imageAnchor.identifier
// Delete anchor from the session to reactivate the image recognition
self.sceneView.session.remove(anchor: anchor)
}
}
Delete the node when the timer is finished indicating that there was no new ARImageAnchor found.
#objc
func imageLost(_ sender:Timer){
self.currentNode!.removeFromParentNode()
self.currentNode = nil
}
In this way the currently added scnNode wil be deleted when the image is covered or when there is found a new image.
This solution does unfortunately not solve the positioning problem of images because of the following:
ARKit doesn’t track changes to the position or orientation of each detected image.
I don't think this is currently possible.
From the Recognizing Images in an AR Experience documentation:
Design your AR experience to use detected images as a starting point for virtual content.
ARKit doesn’t track changes to the position or orientation of each detected image. If you try to place virtual content that stays attached to a detected image, that content may not appear to stay in place correctly. Instead, use detected images as a frame of reference for starting a dynamic scene.
New Answer for iOS 12.0
ARKit 2.0 and iOS 12 finally adds this feature, either via ARImageTrackingConfiguration or via the ARWorldTrackingConfiguration.detectionImages property that now also tracks the position of the images.
The Apple documentation to ARImageTrackingConfiguration lists advantages of both methods:
With ARImageTrackingConfiguration, ARKit establishes a 3D space not by tracking the motion of the device relative to the world, but solely by detecting and tracking the motion of known 2D images in view of the camera. ARWorldTrackingConfiguration can also detect images, but each configuration has its own strengths:
World tracking has a higher performance cost than image-only tracking, so your session can reliably track more images at once with ARImageTrackingConfiguration.
Image-only tracking lets you anchor virtual content to known images only when those images are in view of the camera. World tracking with image detection lets you use known images to add virtual content to the 3D world, and continues to track the position of that content in world space even after the image is no longer in view.
World tracking works best in a stable, nonmoving environment. You can use image-only tracking to add virtual content to known images in more situations—for example, an advertisement inside a moving subway car.
The correct way to check if an image that you are tracking is not currently tracked by ARKit is by using the "isTracked" property in the ARImageAnchor on the didUpdate node for anchor function.
For that, I use the next struct:
struct TrackedImage {
var name : String
var node : SCNNode?
}
And then an array of that struct with the name of all the images.
var trackedImages : [TrackedImage] = [ TrackedImage(name: "image_1", node: nil) ]
Then in the didAdd node for anchor, set the new content to the scene and also add the node to the corresponding element in the array of trackedImages
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
// Check if the added anchor is a recognized ARImageAnchor
if let imageAnchor = anchor as? ARImageAnchor{
// Get the reference ar image
let referenceImage = imageAnchor.referenceImage
// Create a plane to match the detected image.
let plane = SCNPlane(width: referenceImage.physicalSize.width, height: referenceImage.physicalSize.height)
plane.firstMaterial?.diffuse.contents = UIColor(red: 1, green: 1, blue: 1, alpha: 0.5)
// Create SCNNode from the plane
let planeNode = SCNNode(geometry: plane)
planeNode.eulerAngles.x = -.pi / 2
// Add the plane to the scene.
node.addChildNode(planeNode)
// Add the node to the tracked images
for (index, trackedImage) in trackedImages.enumerated(){
if(trackedImage.name == referenceImage.name){
trackedImage[index].node = planeNode
}
}
}
}
Finally in the didUpdate node for anchor function we search for the anchor name in our array and check if the property isTracked is false.
func renderer(_ renderer: SCNSceneRenderer, didUpdate node: SCNNode, for anchor: ARAnchor) {
var trackedImages : [TrackedImage] = [ TrackedImage(name: "image_1", node: nil) ]
if let imageAnchor = anchor as? ARImageAnchor{
// Search the corresponding node for the ar image anchor
for (index, trackedImage) in trackedImages.enumerated(){
if(trackedImage.name == referenceImage.name){
// Check if track is lost on ar image
if(imageAnchor.isTracked){
// The image is being tracked
trackedImage.node?.isHidden = false // Show or add content
}else{
// The image is lost
trackedImage.node?.isHidden = true // Hide or delete content
}
break
}
}
}
}
This solution works when you want to tracked multiple images at the same time and know when any of them is lost.
Note: For this solution to work the maximumNumberOfTrackedImages in the AR configuration must be set to a nonzero number.
For what its worth, I spent hours trying to figure out how to constantly check for image references. The didUpdate function was the answer. Then you just need to test of the reference image is being tracked using the .isTracked property. At that point, you can set the .isHidden property to true or false. Heres my example:
func renderer(_ renderer: SCNSceneRenderer, didUpdate node: SCNNode, for anchor: ARAnchor) {
let trackedNode = node
if let imageAnchor = anchor as? ARImageAnchor{
if (imageAnchor.isTracked) {
trackedNode.isHidden = false
print("\(trackedNode.name)")
}else {
trackedNode.isHidden = true
//print("\(trackedImageName)")
print("No image in view")
}
}
}
I'm not entirely sure I have understood what your asking (so apologies), but if I have then perhaps this might help...
It seems that for insideOfFrustum to work correctly, that their must be some SCNGeometry associated with the node for it to work (an SCNNode alone will not suffice).
For example if we do something like this in the delegate callback and save the added SCNNode into an array:
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
//1. If Out Target Image Has Been Detected Than Get The Corresponding Anchor
guard let currentImageAnchor = anchor as? ARImageAnchor else { return }
//2. Print The Anchor ID & It's Associated Node
print("""
Anchor With ID Has Been Detected \(currentImageAnchor.identifier)
Associated Node Details = \(node)
""")
//3. Store The Node
imageTargets.append(node)
}
And then use the insideOfFrustum method, 99% of the time it will say that the node is in view even when we know it shouldn't be.
However if we do something like this (whereby we create a transparent marker node e.g. one that has some geometry):
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
//1. If Out Target Image Has Been Detected Than Get The Corresponding Anchor
guard let currentImageAnchor = anchor as? ARImageAnchor else { return }
//2. Print The Anchor ID & It's Associated Node
print("""
Anchor With ID Has Been Detected \(currentImageAnchor.identifier)
Associated Node Details = \(node)
""")
//3. Create A Transpanrent Geometry
node.geometry = SCNSphere(radius: 0.1)
node.geometry?.firstMaterial?.diffuse.contents = UIColor.clear
//3. Store The Node
imageTargets.append(node)
}
And then call the following method, it does detect if the ARReferenceImage is inView:
func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
//1. Get The Current Point Of View
guard let pointOfView = augmentedRealityView.pointOfView else { return }
//2. Loop Through Our Image Target Markers
for addedNode in imageTargets{
if augmentedRealityView.isNode(addedNode, insideFrustumOf: pointOfView){
print("Node Is Visible")
}else{
print("Node Is Not Visible")
}
}
}
In regard to your other point about an SCNNode being occluded by another one, the Apple Docs state that the inViewOfFrostrum:
does not perform occlusion testing. That is, it returns
true if the tested node lies within the specified viewing frustum
regardless of whether that node’s contents are obscured by other
geometry.
Again, apologies if I haven't understood you correctly, but hopefully it might help to some extent...
Update:
Now I fully understand your question, I agree with #orangenkopf that this isn't possible. Since as the docs state:
ARKit doesn’t track changes to the position or orientation of each
detected image.
From the Recognizing Images in an AR Experience documentation:
ARKit adds an image anchor to a session exactly once for each
reference image in the session configuration’s detectionImages array.
If your AR experience adds virtual content to the scene when an image
is detected, that action will by default happen only once. To allow
the user to experience that content again without restarting your app,
call the session’s remove(anchor:) method to remove the corresponding
ARImageAnchor. After the anchor is removed, ARKit will add a new
anchor the next time it detects the image.
So, maybe you can find a workaround for your case:
Let's say we are that structure which saves our ARImageAnchor detected and the virtual content associated:
struct ARImage {
var anchor: ARImageAnchor
var node: SCNNode
}
Then, when the renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) is called, you save the image detected into a temporary list of ARImage:
...
var tmpARImages: [ARImage] = []
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
guard let imageAnchor = anchor as? ARImageAnchor else { return }
let referenceImage = imageAnchor.referenceImage
// If the ARImage does not exist
if !tmpARImages.contains(where: {$0.anchor.referenceImage.name == referenceImage.name}) {
let virtualContent = SCNNode(...)
node.addChildNode(virtualContent)
tmpARImages.append(ARImage(anchor: imageAnchor, node: virtualContent))
}
// Delete anchor from the session to reactivate the image recognition
sceneView.session.remove(anchor: anchor)
}
If you understood, while your camera's view point out of the image/marker, the delegate function will loop endlessly... (because we removed the anchor from the session).
The idea will be to combine the image recognition loop, the image detected saved into the tmp list and the sceneView.isNode(node, insideFrustumOf: pointOfView) function to determine if the image/marker detected is no longer view.
I hope it was clear...
This code works only if You hold the device strictly horizontally or vertically. If You hold iPhone tilted or starting to tilt if, this code doesn't work:
func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
//1. Get The Current Point Of View
guard let pointOfView = augmentedRealityView.pointOfView else { return }
//2. Loop Through Our Image Target Markers
for addedNode in imageTargets{
if augmentedRealityView.isNode(addedNode, insideFrustumOf: pointOfView){
print("Node Is Visible")
}else{
print("Node Is Not Visible")
}
}
}

ARAnchor for SCNNode

I'm trying to get a hold of the anchor after adding an SCNNode to the scene of an ARSCNView. My understanding is that the anchor should be created automatically, but I can't seem to retrieve it.
Below is how I add it. The node is saved in a variable called testNode.
let node = SCNNode()
node.geometry = SCNBox(width: 0.5, height: 0.1, length: 0.3, chamferRadius: 0)
node.geometry?.firstMaterial?.diffuse.contents = UIColor.green
sceneView.scene.rootNode.addChildNode(node)
testNode = node
Here is how I try to retrieve it. It always prints nil.
if let testNode = testNode {
print(sceneView.anchor(for: testNode))
}
Does it not create the anchor? If it does: is there another method I can use to retrieve it?
If you have a look at the Apple Docs it states that:
To track the positions and orientations of real or virtual objects
relative to the camera, create anchor objects and use the add(anchor:)
method to add them to your AR session.
As such, I think that since your aren't using PlaneDetection you would need to create an ARAnchor manually if it is needed:
Whenever you place a virtual object, always add an ARAnchor representing its position and orientation to the ARSession. After moving a virtual object, remove the anchor at the old position and create a new anchor at the new position. Adding an anchor tells ARKit that a position is important, improving world tracking quality in that area and helping virtual objects appear to stay in place relative to real-world surfaces.
You can read more about this in the following thread What's the difference between using ARAnchor to insert a node and directly insert a node?
Anyway, in order to get you started I began by creating an SCNNode called currentNode:
var currentNode: SCNNode?
Then using a UITapGestureRecognizer I created an ARAnchor manually at the touchLocation:
#objc func handleTap(_ gesture: UITapGestureRecognizer){
//1. Get The Current Touch Location
let currentTouchLocation = gesture.location(in: self.augmentedRealityView)
//2. If We Have Hit A Feature Point Get The Result
if let hitTest = augmentedRealityView.hitTest(currentTouchLocation, types: [.featurePoint]).last {
//2. Create An Anchore At The World Transform
let anchor = ARAnchor(transform: hitTest.worldTransform)
//3. Add It To The Scene
augmentedRealitySession.add(anchor: anchor)
}
}
Having added the anchor, I then used the ARSCNViewDelegate callback to create the currentNode like so:
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
if currentNode == nil{
currentNode = SCNNode()
let nodeGeometry = SCNBox(width: 0.2, height: 0.2, length: 0.2, chamferRadius: 0)
nodeGeometry.firstMaterial?.diffuse.contents = UIColor.cyan
currentNode?.geometry = nodeGeometry
currentNode?.position = SCNVector3(anchor.transform.columns.3.x, anchor.transform.columns.3.y, anchor.transform.columns.3.z)
node.addChildNode(currentNode!)
}
}
In order to test that it works, e.g being able to log the corresponding ARAnchor, I changed the tapGesture method to include this at the end:
if let anchorHitTest = augmentedRealityView.hitTest(currentTouchLocation, options: nil).first,{
print(augmentedRealityView.anchor(for: anchorHitTest.node))
}
Which in my ConsoleLog prints:
Optional(<ARAnchor: 0x1c0535680 identifier="23CFF447-68E9-451D-A64D-17C972EB5F4B" transform=<translation=(-0.006610 -0.095542 -0.357221) rotation=(-0.00° 0.00° 0.00°)>>)
Hope it helps...

Unable to differentiate between plane detected by ARKit and a digital object to be placed using HitTest

I'm fairly new to iOS Swift programming. I'm using ARKit to build a very basic app to detect a horizontal plane and place,translate,rotate,modify or delete an object on it.
My main concern is to differential between the plane detected by ARKit and a digital object that I've placed. My thinking was to use hitTest(:options:) to select the object (if any) and hitTest(:types:) to select the plane through a tap gesture. I'm attaching the relevant code snippet below.
#objc func tapped(_ gesture: UITapGestureRecognizer){
let sceneView = gesture.view as! ARSCNView
let location = gesture.location(in: sceneView)
let hitTestOptions: [SCNHitTestOption: Any] = [.boundingBoxOnly: true]
let existingNodeHitTest = sceneView.hitTest(location, options: hitTestOptions)
if let existingNode = existingNodeHitTest.first?.node {
// Move, rotate, modify or delete the object
} else {
// Option to add other objects
let hitTest = sceneView.hitTest(location, types: .existingPlaneUsingExtent)
if !hitTest.isEmpty {
let node = findNode(at: location)
if node !== selectedNode {
self.addItems(hitTestResult: hitTest.first!)
}
}
}
}
func addItems(hitTestResult: ARHitTestResult) {
let scene = SCNScene(named: "BuildingModels.scnassets/model/model.scn")
let itemNode = (scene?.rootNode.childNode(withName: "SketchUp", recursively: false))!
let transform = hitTestResult.worldTransform
let position = SCNVector3(transform.columns.3.x,transform.columns.3.y,transform.columns.3.z)
itemNode.position = position
// self.sceneView.scene.lightingEnvironment.contents = scene.lightingEnvironment.contents
self.sceneView.scene.rootNode.addChildNode(itemNode)
selectedNode = itemNode
}
func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
guard let planeAnchor = anchor as? ARPlaneAnchor else {return}
let gridNode = createGrid(planeAnchor: planeAnchor)
node.addChildNode(gridNode)
}
func renderer(_ renderer: SCNSceneRenderer, didUpdate node: SCNNode, for anchor: ARAnchor) {
guard let planeAnchor = anchor as? ARPlaneAnchor else {return}
node.enumerateChildNodes { (childNode, _) in
childNode.removeFromParentNode()
}
let gridNode = createGrid(planeAnchor: planeAnchor)
node.addChildNode(gridNode)
}
When I run the code, the hitTest(_:options:) returns the plane detected. Are there any ways to select only the SCNNodes (objects) that I place and not the plane detected. Am I missing something? Any help is highly appreciated.
Thanks,
Sourabh.
Looking at your question you are already half way there.
The way to handle this in it's entirety, is to make use of the following HitTest functions within your UITapGestureRecognizer function:
(1) An ARSCNHitTest which:
Searches for real-world objects or AR anchors in the captured camera image corresponding to a point in the SceneKit view.
(2) AnSCNHitTest which:
Looks for SCNGeometry objects along the ray you specify. For each intersection between the ray and and a geometry, SceneKit creates a hit-test result to provide information about both the SCNNode object containing the geometry and the location of the intersection on the geometry’s surface.
Using your UITapGestureRecognizer as an example therefore, you can differentiate between an ARPlaneAnchor (detectedPlane) and any SCNNode within your scene like so:
#objc func handleTap(_ gesture: UITapGestureRecognizer){
//1. Get The Current Touch Location
let currentTouchLocation = gesture.location(in: self.augmentedRealityView)
//2. Perform An ARNSCNHitTest To See If We Have Hit An ARPlaneAnchor
if let planeHitTest = augmentedRealityView.hitTest(currentTouchLocation, types: .existingPlane).first,
let planeAnchor = planeHitTest.anchor as? ARPlaneAnchor{
print("User Has Tapped On An Existing Plane = \(planeAnchor.identifier)")
return
}
//3. Perform An SCNHitTest To See If We Have Hit An SCNNode
if let nodeHitTest = augmentedRealityView.hitTest(currentTouchLocation, options: nil).first {
let nodeTapped = nodeHitTest.node
print("An SCNNode Has Been Tapped = \(nodeTapped)")
return
}
}
If you make use of the name property for any of your SCNNode’s this will also help you further e.g:
if let name = nodeTapped.name{
print("An SCNNode Named \(name) Has Been Tapped")
}
Additionally, if you ONLY want to detect objects you have added e.g SCNNodes then you can simply remove part two of the getureRecognizer function.
Hope it helps...
To fix this issue, you should loop through your scene nodes, after that you can manipulate with your wanted node. Example:
for node in sceneView.scene.rootNode.childNodes {
if node.name == "yorNodeName" {
// do your manipulations
}
}
Don't forget to add name to your nodes. Example:
node.name = "yorNodeName"
I hope it helped!