QR Code Tracking Sample

This sample demonstrates how to detect and track QR codes in the real world. In order to use this feature it must be enabled in the OpenXR plugin settings located under Project Settings > XR Plug-in Management > OpenXR (> Android Tab).

How the sample works

Adding the SpacesQrCodeManager component to the AR Session Origin GameObject will enable the QR code Tracking Subsystem included in the Snapdragon Spaces package. The component provides six (6) fields:

• The Marker Prefab object is instantiated every time a QR code is detected. Tracking will work only if Marker Tracking is enabled.
• The Marker Tracking Mode is set for all tracked markers. For more information on what each Tracking Mode does, see the Image Tracking documentation.

TRACKING MODE LIMITATION

Only the dynamic tracking mode is supported by the Snapdragon Spaces Services 0.19.1.

Tracking Mode	Added	Updated	Removed
Dynamic (default)	Marker detected	Every frame	Marker detection lost
Static	Marker detected	Never	New marker tracked
Adaptive	Marker detected	Immediately with head movement and periodically for marker movement	Marker detection lost

• The Marker Tracking field enables and disables the tracking capabilities of the feature. QR code detection will run continuously, but tracking can be disabled if not needed.
• Marker Size is the width and height in meters of the physical markers to be detected. Correct measurements are essential for accurate pose estimation and subsequent placement of any augmentations.
• Minimum QR Version and Maximum QR Version are the versions of QR codes which will be detected. Any QR codes outside of this range will not be detected or tracked.

Subscribing to the SpacesQrCodeManager::OnMarkersChanged method allows developers to use a familiar ARFoundation pattern to get the position, orientation, and string data of the tracked marker, as seen in the simplified code example below.

    private override void Start() {
        FindObjectOfType<SpacesQrCodeManager>().markersChanged += OnMarkersChanged;
    }

    private void OnMarkersChanged(SpacesMarkersChangedEventArgs args) {
        foreach (var marker in args.added) {
            ...
        }

        foreach (var marker in args.updated) {
            ...
        }

        foreach (var marker in args.removed) {
            ...
        }
    }

RECOMMENDATIONS AND LIMITATIONS

• Maximum recognition distance decreases with higher QR code versions.
• To ensure recognition from a distance of 1 meter or more, it is recommended to use QR codes with a version number between 1 and 6.
• QR codes can be detected at a viewing angle of up to 45 degrees.
• There is limited support for artistic QR codes. Standard black on white rectangular module patterns are recognized most easily. Logo's are supported but GenAI QR codes are unlikely to work.
• Printing the QR code on non-reflective paper improves detection and decoding of QR codes.
• The QR code size should be measured without including silent regions, using the finder pattern as boundaries.

Decoding a QR Code

The decoded QR code string is stored in SpacesARMarker.Data. The SpacesARMarker is created every time a QR code is detected, and destroyed when the QR code tracking is lost. Before accessing the SpacesARMarker.Data value, make sure that SpacesARMarker.IsMarkerDataAvailable is true since tracking could run before the QR code is decoded.

Tracking a QR Code

Turning on Marker Tracking in the SpacesQRCodeManager will enable the subsystem to track the pose of any detected QR codes. Turn it off in order to increase performance when not in use.

Enabling and Disabling the SpacesQrCodeManager

Enabling and disabling the SpacesQrCodeManager component will Start and Stop the subsystem respectively. A restart of the subsystem will be required if there are any modifications for the SpacesQrCodeManager variables. To restart simply disable and then re-enable the SpacesQrCodeManager component.

tip

Enabling or disabling Marker Tracking does not need a subsystem restart to take effect.

SpacesQrCodeManager manager;

manager.enabled = false;
manager.markerSize = new Vector2(20.0f, 20.0f);
manager.markerTrackingMode = MarkerTrackingMode.Dynamic;
manager.enabled = true;