Resolved Extended image tracking ARKit

I am using ARKit's image tracking to place an object at a certain position. If the image is lost, I want the object to stay in the same position as it got tracked initially. But unfortunately the extended tracking is no success. When the image is lost, the object takes in a different position farther away from where it was initially tracked. What should I do in this script?

Code (CSharp):

1. using System.Collections.Generic;
2. using System.Linq;
3. using UnityEngine;
4. using UnityEngine.UI;
5. using UnityEngine.Events;
6. using UnityEngine.XR.ARFoundation;
7. using UnityEngine.XR.ARSubsystems;
8.  
9. public class ARImageAnchor : MonoBehaviour
10. {
11.    public string ReferenceImageName;
12.    private ARTrackedImageManager _TrackedImageManager;
13.    public Text text_;
14.  
15.    public ARTrackedImageManager arTracked;
16.  
17.    private void Awake()
18.    {
19.        _TrackedImageManager = FindObjectOfType<ARTrackedImageManager>();
20.    }
21.  
22.    private void OnEnable()
23.    {
24.        if (_TrackedImageManager != null)
25.        {
26.            _TrackedImageManager.trackedImagesChanged += OnTrackedImagesChanged;
27.        }
28.    }
29.  
30.    private void OnDisable()
31.    {
32.        if (_TrackedImageManager != null)
33.        {
34.            _TrackedImageManager.trackedImagesChanged -= OnTrackedImagesChanged;
35.        }
36.    }
37.  
38.    private void OnTrackedImagesChanged(ARTrackedImagesChangedEventArgs e)
39.    {
40.  
41.        foreach (var trackedImage in e.added)
42.        {
43.            Debug.Log($"Tracked image detected: {trackedImage.referenceImage.name} with size: {trackedImage.size}");
44.  
45.            if(trackedImage.referenceImage.name == this.ReferenceImageName)
46.            {
47.                this.gameObject.GetComponent<MeshRenderer>().enabled = true;
48.            }
49.        }
50.  
51.        UpdateTrackedImages(e.added);
52.        UpdateTrackedImages(e.updated);
53.    }
54.  
55.    private void UpdateTrackedImages(IEnumerable<ARTrackedImage> trackedImages)
56.    {
57.        // If the same image (ReferenceImageName)
58.        var trackedImage =
59.            trackedImages.FirstOrDefault(x => x.referenceImage.name == ReferenceImageName);
60.        if (trackedImage == null)
61.        {
62.            return;
63.        }
64.  
65.        if (trackedImage.trackingState != TrackingState.None)
66.        {
67.            var trackedImageTransform = trackedImage.transform;
68.            transform.SetPositionAndRotation(new Vector3(trackedImageTransform.position.x + 0.5f, trackedImageTransform.position.y, trackedImageTransform.position.z), Quaternion.Euler(0, 0, 0));
69.        }
70.    }
71.  
72.  
73.  
74. }

 

Try to update image's position only if trackingState == TrackingState.Tracking.

 

But I want the image to stay in the same position after the tracking is lost. How can I achieve this?

 

Your image will stay on the last position which had TrackingState.Tracking state.

 

I tried it like this:

Code (CSharp):

1. if (trackedImage.trackingState == TrackingState.Tracking)
2.        {
3.            var trackedImageTransform = trackedImage.transform;
4.            transform.SetPositionAndRotation(new Vector3(trackedImageTransform.position.x + 0.5f, trackedImageTransform.position.y, trackedImageTransform.position.z), Quaternion.Euler(0, 0, 0));
5.        }

Unfortunately when I hide the image, the object gets move further away.

 

Tracking drift may occur if there is not enough tracking information available. Please try to move your phone further from the image and ensure there are enough landmark features in your environment.
For example, ARKit/ARCore has a hard time tracking camera position against solid-color walls or floor.

 

Yes initially I tried it on different surfaces. But I just feel it sets a new position when the image is no longer in view.

 

Maybe you should try a different approach. When you've detected an image, ask a user to confirm the placement and remember the current position.

 

Hmm but from this forum: https://forum.unity.com/threads/image-tracking-extended.618202/
There has been some luck. Dont know how to apply it in my code.

 

Hey it works. My mistake was I had given higher size of the image to be tracked. It was suppose to be 5 cm and I gave it as 15cm. Now it works well

 

Hello,
I'm trying to achieve extended image tracking using ARKit.
Can anyone tell how to enable extended image tracking in ARKit like as in Vuforia we simply select the extended tracking option.

 

//********************************************************************************************************************** //
Hello @saifshk17, I'm new to Unity working on Extended Image Tracking POC using ARFoundation follow the script that you've shared. But I'm getting one compile below error:

*error CS1061: 'IEnumerable<ARTrackedImage>' does not contain a definition for 'FirstOrDefault' and no accessible extension method 'FirstOrDefault' accepting a first argument of type 'IEnumerable<ARTrackedImage>' could be found (are you missing a using directive or an assembly reference?)*

I crossed check multiple times like if I missing any thing but it's not.

Could you please help me here. I'm using Unity 2021.3.2f1.

Thanks in advance.
Amit