Fixed Position for 3D Model on ImageTarget with Vuforia

Question

I am developing an AR application, with Vuforia ImageTarget I added a QR code to be scanned. When scan the qr code I want my 3d model appear with fixed point and scale on the screen and do not track ImageTarget anymore.

Default Observer Event Handler script at Vuforia Package has 3 options which Tracked, Tracked or Extended Tracked and Tracked,Extenden Tracked or Limited but non of these options are not satisfy what I want. I just want to scan QR code once the model should appears on screen with fixed point and scale then 3d model should not track ImageTarget anymore. Also I read Vuforia Images&Objects Library but can not find a useful tip.

Answer 1

First of all thanks to all who contribute to solve this problem. With help of @charanvendra I revise the code and finally solve the problem. For those who is faced with similar problems like I do the code :

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Vuforia;

public class QRTrackerHandler : MonoBehaviour
{
    private ObserverBehaviour mObserverBehaviour;
    private bool isModelDisplayed = false;

    public GameObject model;  // Assign 3D model in the inspector

    private GameObject modelContainer; // Create a container which positioned according to camera

    void Start()
    {
        mObserverBehaviour = GetComponent<ObserverBehaviour>();
        if (mObserverBehaviour)
        {
            mObserverBehaviour.OnTargetStatusChanged += OnTargetStatusChanged;
        }

        if (model != null)
        {
            model.SetActive(false);  // Initially hide the model
            CreateModelContainer();
        }
    }

    private void OnDestroy()
    {
        if (mObserverBehaviour)
        {
            mObserverBehaviour.OnTargetStatusChanged -= OnTargetStatusChanged;
        }
    }

    private void OnTargetStatusChanged(ObserverBehaviour behaviour, TargetStatus targetStatus)
    {
        if (!isModelDisplayed && (targetStatus.Status == Status.TRACKED ||
                                  targetStatus.Status == Status.EXTENDED_TRACKED))
        {
            DisplayModel();
            isModelDisplayed = true;
            DisableTracking();
        }
    }

    private void CreateModelContainer()
    {
        modelContainer = new GameObject("ModelContainer");
        modelContainer.transform.SetParent(Camera.main.transform);
        modelContainer.transform.localPosition = new Vector3(0, 0, 275);  // Adjust the Z value as needed
        modelContainer.transform.localRotation = Quaternion.Euler(-90, 0, 0); // RotateModel to show as needed
        modelContainer.transform.localScale = Vector3.one;

        model.transform.SetParent(modelContainer.transform);
        model.transform.localPosition = Vector3.zero;
        model.transform.localRotation = Quaternion.identity;
        model.transform.localScale = Vector3.one;
    }

    private void DisplayModel()
    {
        if (model != null)
        {
            model.SetActive(true);  // Show the model
        }
    }

    private void DisableTracking()
    {
        if (mObserverBehaviour)
        {
            mObserverBehaviour.OnTargetStatusChanged -= OnTargetStatusChanged;
        }
    }
}

Do not need to use System.Collections;