Marker Tracker Example
This section includes an example of detecting Fiducial Markers on the Magic Leap 2 headset.
Simple Example
This script detects markers and creates a cube at each of the target's location. The script does not handle runtime changes to the Marker Tracker settings.
caution
This feature requires the MARKER_TRACKING permission to be enabled in your project's Manifest Settings. (Edit > Project Settings > Magic Leap > Manifest Settings)
using System.Collections.Generic;
using System.Text;
using UnityEngine;
using UnityEngine.XR.MagicLeap;
public class MarkerTrackerExample : MonoBehaviour
{
public float QrCodeMarkerSize = 0.1f;
public float ArucoMarkerSize = 0.1f;
public MLMarkerTracker.MarkerType Type = MLMarkerTracker.MarkerType.QR;
public MLMarkerTracker.ArucoDictionaryName ArucoDict = MLMarkerTracker.ArucoDictionaryName.DICT_5X5_100;
public MLMarkerTracker.Profile Profile = MLMarkerTracker.Profile.Default;
private Dictionary<string, GameObject> _markers = new Dictionary<string, GameObject>();
private ASCIIEncoding _asciiEncoder = new System.Text.ASCIIEncoding();
#if UNITY_ANDROID
private void OnEnable()
{
MLMarkerTracker.OnMLMarkerTrackerResultsFound += OnTrackerResultsFound;
}
private void Start()
{
MLMarkerTracker.TrackerSettings trackerSettings = MLMarkerTracker.TrackerSettings.Create(
true, Type, QrCodeMarkerSize, ArucoDict, ArucoMarkerSize, Profile);
_ = MLMarkerTracker.SetSettingsAsync(trackerSettings);
}
private void OnDisable()
{
MLMarkerTracker.OnMLMarkerTrackerResultsFound -= OnTrackerResultsFound;
_ = MLMarkerTracker.StopScanningAsync();
}
private void OnTrackerResultsFound(MLMarkerTracker.MarkerData data)
{
string id = "";
float markerSize = .01f;
switch (data.Type)
{
case MLMarkerTracker.MarkerType.Aruco_April:
id = data.ArucoData.Id.ToString();
markerSize = ArucoMarkerSize;
break;
case MLMarkerTracker.MarkerType.QR:
id = _asciiEncoder.GetString(data.BinaryData.Data, 0, data.BinaryData.Data.Length);
markerSize = QrCodeMarkerSize;
break;
case MLMarkerTracker.MarkerType.EAN_13:
case MLMarkerTracker.MarkerType.UPC_A:
id = _asciiEncoder.GetString(data.BinaryData.Data, 0, data.BinaryData.Data.Length);
Debug.Log("No pose is given for marker type " + data.Type + " value is " + data.BinaryData.Data);
break;
}
if (!string.IsNullOrEmpty(id))
{
if (_markers.ContainsKey(id))
{
GameObject marker = _markers[id];
marker.transform.position = data.Pose.position;
marker.transform.rotation = data.Pose.rotation;
}
else
{
//Create a primitive cube
GameObject marker = GameObject.CreatePrimitive(PrimitiveType.Cube);
//Render the cube with the default URP shader
marker.AddComponent<Renderer>();
marker.GetComponent<Renderer>().material = new Material(Shader.Find("Universal Render Pipeline/Lit"));
marker.transform.position = data.Pose.position;
marker.transform.rotation = data.Pose.rotation;
marker.transform.localScale = new Vector3(markerSize, markerSize, markerSize);
_markers.Add(id, marker);
}
}
}
#endif
}
Custom Profile Example
An example scripts that detects markers using a custom profile.
caution
This feature requires the MARKER_TRACKING permission to be enabled in your project's Manifest Settings. (Edit > Project Settings > Magic Leap > Manifest Settings)
using System.Collections.Generic;
using System.Text;
using UnityEngine;
using UnityEngine.XR.MagicLeap;
public class MarkerTrackerExample : MonoBehaviour
{
[Header("Marker Tracker Settings")]
// QR Code marker size to use (in meters).
public float QRCodeSize = 0.1f;
// Aruco marker size to use (in meters).
public float ArucoMarkerSize = 0.1f;
// The marker types that are enabled for this scanner. Enable markers by
// combining any number of <c> MarkerType </c> flags using '|' (bitwise 'or').
public MLMarkerTracker.MarkerType MarkerTypes = MLMarkerTracker.MarkerType.Aruco_April| MLMarkerTracker.MarkerType.QR;
// Aruco dictionary to use.
public MLMarkerTracker.ArucoDictionaryName ArucoDicitonary = MLMarkerTracker.ArucoDictionaryName.DICT_5X5_100;
// Represents the different tracker profiles used to optimize marker tracking in difference use cases.
public MLMarkerTracker.Profile TrackerProfile = MLMarkerTracker.Profile.Custom;
[Header("Marker Tracker Custom Profile")]
// A hint to the back-end the max frames per second hat should be analyzed.
public MLMarkerTracker.FPSHint FPSHint;
// A hint to the back-end the resolution that should be used.
public MLMarkerTracker.ResolutionHint ResolutionHint;
// A hint to the back-end for the cameras that should be used.
public MLMarkerTracker.CameraHint CameraHint;
// In order to improve performance, the detectors don't always run on the full
// frame.Full frame analysis is however necessary to detect new markers that
// weren't detected before. Use this option to control how often the detector may
// detect new markers and its impact on tracking performance.
public MLMarkerTracker.FullAnalysisIntervalHint FullAnalysisIntervalHint;
// This option provides control over corner refinement methods and a way to
// balance detection rate, speed and pose accuracy. Always available and
// applicable for Aruco and April tags.
public MLMarkerTracker.CornerRefineMethod CornerRefineMethod;
// Run refinement step that uses marker edges to generate even more accurate
// corners, but slow down tracking rate overall by consuming more compute.
// Aruco/April tags only.
public bool UseEdgeRefinement;
private Dictionary<string, GameObject> _markers = new Dictionary<string, GameObject>();
private ASCIIEncoding _asciiEncoder = new System.Text.ASCIIEncoding();
private MLMarkerTracker.TrackerSettings _markerSettings;
//Enable scanning on start?
private bool _enableMarkerScanning = true;
#if UNITY_ANDROID
private void OnEnable()
{
MLMarkerTracker.OnMLMarkerTrackerResultsFoundArray += OnMLMarkerTrackerResultsFoundArray;
}
private void Start()
{
// Unity has it's own value for Enum called Everything and sets it to -1
MarkerTypes = (int)MarkerTypes == -1 ? MLMarkerTracker.MarkerType.All : MarkerTypes;
// If we are using a custom profile, create the profile before creating the tracker settings
if (TrackerProfile == MLMarkerTracker.Profile.Custom)
{
MLMarkerTracker.TrackerSettings.CustomProfile customProfile = MLMarkerTracker.TrackerSettings.CustomProfile.Create(FPSHint, ResolutionHint, CameraHint, FullAnalysisIntervalHint, CornerRefineMethod, UseEdgeRefinement);
_markerSettings = MLMarkerTracker.TrackerSettings.Create(
_enableMarkerScanning, MarkerTypes, QRCodeSize, ArucoDicitonary, ArucoMarkerSize, TrackerProfile, customProfile);
}
else
{
_markerSettings = MLMarkerTracker.TrackerSettings.Create(
_enableMarkerScanning, MarkerTypes, QRCodeSize, ArucoDicitonary, ArucoMarkerSize, TrackerProfile);
}
MLMarkerTracker.SetSettingsAsync(_markerSettings).GetAwaiter().GetResult();
}
private void OnDisable()
{
MLMarkerTracker.OnMLMarkerTrackerResultsFoundArray -= OnMLMarkerTrackerResultsFoundArray;
}
private void OnMLMarkerTrackerResultsFoundArray(MLMarkerTracker.MarkerData[] dataArray)
{
foreach (MLMarkerTracker.MarkerData data in dataArray)
{
ProcessSingleMarker(data);
}
}
private void ProcessSingleMarker(MLMarkerTracker.MarkerData data)
{
string id = "";
float markerSize = .01f;
switch (data.Type)
{
case MLMarkerTracker.MarkerType.Aruco_April:
id = data.ArucoData.Id.ToString();
markerSize = ArucoMarkerSize;
break;
case MLMarkerTracker.MarkerType.QR:
id = _asciiEncoder.GetString(data.BinaryData.Data, 0, data.BinaryData.Data.Length);
markerSize = QRCodeSize;
break;
case MLMarkerTracker.MarkerType.EAN_13:
case MLMarkerTracker.MarkerType.UPC_A:
id = _asciiEncoder.GetString(data.BinaryData.Data, 0, data.BinaryData.Data.Length);
Debug.Log("No pose is given for marker type " + data.Type + " value is " + data.BinaryData.Data);
break;
}
if (!string.IsNullOrEmpty(id))
{
if (_markers.ContainsKey(id))
{
GameObject marker = _markers[id];
marker.transform.position = data.Pose.position;
marker.transform.rotation = data.Pose.rotation;
}
else
{
//Create a primitive cube
GameObject marker = GameObject.CreatePrimitive(PrimitiveType.Cube);
//Render the cube with the default URP shader
marker.AddComponent<Renderer>();
marker.GetComponent<Renderer>().material = new Material(Shader.Find("Universal Render Pipeline/Lit"));
marker.transform.localScale = new Vector3(markerSize, markerSize, markerSize);
_markers.Add(id, marker);
}
}
}
#endif
}
See also
MLMarkerTracker- API to scan markers and obtain additional data such as 6DOF poses.
MLMarkerTracker.ArucoData- API that contains the data that belongs to Aruco Markers.
MLMarkerTracker.Settings- Marker Tracker Settings API that contains information such as what type of markers, their sizes, and if the Marker tracker is enabled.