AR Foundation place object at a different position on Image Detection

[TheIntellify-Pankaj]

I am working on an app that spawns a model when an image is detected, I need an object to spawn at a different position and also face the camera but i am unable to do that and i am searching on all the site for this but i can't find anything so is there any way to place the 3d model on a different position on image tracking?

[tdmowrer]

Sure, you can do this. Spawning an object a particular position and orientation is straightforward using Instantiate. If you want it to face the camera, you can use the Quaternion.LookAt helper method.

To do this in response to a detected image, you can subscribe to the ARTrackedImageManager's trackedImagesChanged event. This event provides a list of newly detected images, among other things.

[TheIntellify-Pankaj]

i have tried that way but unable to achieve that so i am providing you my code so you can easily understand.

with this code, i am able to instantiate gameobject at the different positions but the gameobject is not steady as you move the device it will also move with the device.

using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using UnityEngine;
using UnityEngine.Networking;
using UnityEngine.XR.ARFoundation;
using UnityEngine.XR.ARSubsystems;
using UnityEngine.UI;

[Serializable]
public class ImageTargetData {
    public string imageTargetName;
    public Vector3 position;
    public Quaternion rotation;
}

public class ImageTrackingController : MonoBehaviour
{

    public ARTrackedImageManager m_ImageManager;

    [SerializeField]
    private GameObject m_ArObjectsToPlace;

    [SerializeField]
    private Vector3 m_ScaleFactor = Vector3.one;

    [SerializeField]
    private Transform rootObject;

    bool isFirstTime = false;

    GameObject m_SpawnedPrefab;
    public GameObject spawnedPrefab
    {
        get => m_SpawnedPrefab;
        set => m_SpawnedPrefab = value;
    }

    public List<ImageTargetData> Pose = new List<ImageTargetData>();

    void Start()
    {
        Init();

    }

    void Init()
    {

        m_ImageManager = GetComponent<ARTrackedImageManager>();
        m_ImageManager.requestedMaxNumberOfMovingImages = 1;
        m_ImageManager.enabled = true;

    }

    void OnEnable()
    {
        m_ImageManager.trackedImagesChanged += ImageManagerOnTrackedImagesChanged;
    }

    void OnDisable()
    {

        m_ImageManager.trackedImagesChanged -= ImageManagerOnTrackedImagesChanged;
    }

    void ImageManagerOnTrackedImagesChanged(ARTrackedImagesChangedEventArgs obj)
    {
        // added, spawn prefab
        foreach (ARTrackedImage image in obj.added)
        {
            Debug.Log("Image ready to tracked : "+image.referenceImage.guid);
        }

        // updated, set prefab position and rotation
        foreach (ARTrackedImage image in obj.updated)
        {
            // image is tracking or tracking with limited state, show visuals and update it's position and rotation
            if (image.trackingState == TrackingState.Tracking)
            {

                if (isFirstTime == false)
                {

                    Debug.Log("IMAGE TARGET NAME : " + image.referenceImage.name);

                    UI_.text = image.referenceImage.name;

                    spawnedPrefab = Instantiate(m_ArObjectsToPlace);
                    spawnedPrefab.transform.SetParent(rootObject);
                    spawnedPrefab.transform.localPosition = Vector3.zero;
                    spawnedPrefab.transform.localScale = Vector3.one;
                    spawnedPrefab.transform.localRotation = Quaternion.Euler(0, 0, 0);

                    rootObject.transform.SetPositionAndRotation(image.transform.position, image.transform.rotation);

                    rootObject.transform.position = new Vector3(0, 0, 10);

                    // spawnedPrefab.transform.localScale = new Vector3(25, 25, 25);

                    //  UI_Rot.text = "After_Position:" + rootObject.transform.position.ToString();

                    //  UI_Rot.text = ("Rotation:"  + rootObject.transform.rotation.x.ToString() +","+ rootObject.transform.rotation.y.ToString() + "," + rootObject.transform.rotation.z.ToString());

                    m_ImageManager.GetComponent<ARTrackedImageManager>().enabled = false;

                    isFirstTime = true;
                }

            }

        }

        // removed, destroy spawned instance
        foreach (ARTrackedImage image in obj.removed)
        {
           // Destroy(rootObject.gameObject);
        }
    }

    public Text UI_;

    public Text UI_Rot;

    public void ReloadScene()
    {
        isFirstTime = false;

        Destroy(spawnedPrefab);

        UI_.text = "Rescan";

        m_ImageManager.GetComponent<ARTrackedImageManager>().enabled = true;
    }
}

[tdmowrer]

What is rootObject?

[TheIntellify-Pankaj]

rootObject Parent object of spawnedPrefab.

i instantiate the spawnedPrefab and make it a child of rootObject.

[tdmowrer]

I understand how it is used in your code, but I was asking what it is set to in the inspector.

However, this issues page is more suitable for issues with the ARFoundation-related packages -- e.g., how to use them, or bug reporting. Your question seems less like an AR specific issue and more of a general Unity usage issue. You might want to peruse some of Unity's learning resources or try a more general Unity forum.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.