In MRUK, QR codes are considered a type of trackable object. The QR code Detection feature enables identification and tracking of QR codes in real-world environments.

Prerequisites

Before starting this tutorial, ensure you have the following:

Hardware requirements

Development machine running one of the following:

Windows 10+ (64-bit)

macOS Sierra 10.10+ (x86 or ARM)

Headset preview requirements

Supported Meta Quest headsets:

Quest 3

Quest 3S and 3S Xbox Edition

Connection between your headset and development machine using one of the following:

USB-C data cable (recommended)

Wi-Fi connection, with both devices on the same network

Account requirements

Unity ID: Create or log in to your Unity account⁠

Meta Horizon developer account: Register a Meta account

SDK requirements

Meta XR Core SDK v83 or later.

Meta MR Utility Kit v83 or later.

Limitations

Design customizations, such as logos, are not supported.

Micro QR codes are not supported.

Works best in well-lit environments.

QR codes should be relatively large and positioned close to the device.

Supports QR code versions up to and including version 10.

When using PC Link, QR code detection may only work properly the first time the PC app is executed (such as entering Play Mode in the Unity Editor). Rebooting the Quest device may resolve the issue. This will be fixed in a future release.

Enable QR code detection in MRUK

To enable QR code detection in MRUK:

Enable Spatial Data Permission on your Meta Quest.

Use Building Blocks to add the Camera Rig and Passthrough Layer to your scene.

Navigate to Meta > Tools > Building Blocks.

Find the Camera Rig and Passthrough Layer Building Blocks and select the Add block to current scene button.

QR code detection requires that Scene, Anchor, and experimental features to be enabled.

Click on Camera Rig > OVR Manager > General > Scene Support and select Required.

Click on Camera Rig > OVR Manager > General > Anchor Support and select Enabled.

Click on Camera Rig > OVR Manager > Experimental and check the Experimental Features Enabled checkbox. This adds the <uses-feature android:name="com.oculus.experimental.enabled" /> tag to the AndroidManifest.xml, as described in Experimental Features

Enable the experimentalEnabled property as described in Experimental Features.

Add an MRUK component to a GameObject in your scene. Then, expand the Scene Settings > Tracker Configuration foldouts and check the QR Code Tracking Enabled box.

Subscribe to the Trackable Added and Trackable Removed events as shown below.

This will have three effects at runtime:

Enables QR code detection. This consumes system resources, so you should disable it when not needed. Quitting the app will also disable QR code tracking and clear detected QR codes.

Periodically checks for newly detected QR codes and invokes the Trackable Added callback.

Updates the poses and dimensions of all detected QR codes.

Representation in Unity

QR codes are a type of trackable (MRUKTrackable). Trackables have a pose and optional data provided as properties. QR codes have the following data:

A 6 degree-of-freedom pose (position and rotation) represented by a UnityEngine.Transform.

A 2D bounding box, accessible from MRUKAnchor.PlaneRect.

A 2D polygon, accessible from MRUKAnchor.PlaneBoundary2D.

A payload (the data encoded in the QR code), accessible from MRUKTrackable.MarkerPayloadString and MRUKTrackable.MarkerPayloadBytes.

Trackable events

When a new trackable is detected, MRUK creates a new GameObject and invokes the TrackableAdded event. Use the MRUKTrackable.TrackableType property to determine what type of trackable was detected:

public void OnTrackableAdded(MRUKTrackable trackable)
{
    if (trackable.TrackableType == OVRAnchor.TrackableType.QRCode)
    {
        // New QR code detected!
    }
}

Use this callback to add your own logic to handle QR codes. MRUK will continue to update the transform of the GameObject it created to represent the QR code.

QR code payload

A QR code payload consists of an array of bytes, accessible via the MRUKTrackable’s MarkerPayloadBytes property. If the byte array is a valid UTF8-encoded string, then the MRUKTrackable’s MarkerPayloadString property will be a valid string representing the payload:

public void OnTrackableAdded(MRUKTrackable trackable)
{
    if (trackable.TrackableType == OVRAnchor.TrackableType.QRCode &&
        trackable.MarkerPayloadString != null)
    {
        Debug.Log($"Detected QR code: {trackable.MarkerPayloadString}");
    }
}

Moving QR codes

When a detected physical QR code moves, the QR code tracker updates its reported pose. However, this is not frame-perfect, as poses are updated at a lower frequency. This means the tracker is not suitable for tracking moving objects in real time, but it will eventually update the pose if the QR code is moved from one location to another within the environment.

QR code sample scene

There is a sample scene called “QRCodeDetection” in the Mixed Reality Utility Kit samples⁠ GitHub repository. It demonstrates the ability to identify and track QR codes using MRUK.

This sample scene enables QR code detection in MRUK’s tracker configuration, and includes scripts that respond to the TrackableAdded and TrackableRemoved callbacks (see QRCodeManager.cs in the Scripts folder). When a QR code is detected, the sample’s QRCodeManager creates a child GameObject with MonoBehaviours that display the payload — either as a string (if possible) or as a subset of the raw bytes — and render the 2D boundary of the QR code.

Within the scene, an information log and control panel are attached to the left controller. You can use the control panel buttons to toggle the QR code tracker on or off and to request Scene permission. Begin by requesting Scene permission; the information panel will indicate when permission has been granted.

QR code detection is part of the Scene API and it requires the spatial data permission.

Once the Spatial Data permission has been granted, point your Quest at any QR code. For example, you can view https://en.wikipedia.org/wiki/QR_code⁠ on a computer screen. You should see an image from the HMD like the one below, where the anchor position and the text encoded in the QR code are displayed by the app when it detects the QR code on the page. The text in white is the text encoded by the QR code, also called the “payload”.