Extras

This section describes additional functions of the VIRNECT Track Framework for Android.

Get Framework Log Messages

The internal framework logs can be dumped to the console with the following command:

Track.dumpLog() 

Regardless of the internal log level, the dumpLog method will always use Android log level Info

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Get Target Meta Information

Meta information about targets, like their type or physical size, can be retrieved by calling getTargetInfo. The method requires an array of types, TargetInformation that is pre-initialized with the requested target names.

// Assuming targetNames is of type String[] 
val targetInfos = targetNames.map{Common.TargetInformation(it)}.toTypedArray()
Track.getTargetInfo(targetInfos)

Modify Trackable Targets at Runtime

The tracking of each target can be activated or deactivated during runtime by modifying the target meta information. To do so, set the mIgnore property of the target information accordingly. The information about whether a target is static or dynamic in a scene can be provided with the mStatic property. By default targets are always considered as dynamic, which means that they can move relative to their environment. Providing the information that a target is static in its environment, will improve the tracking performance.

// Assuming targetNames is of type String[] 
val targetInfos = targetNames.map{Common.TargetInformation(it)}.toTypedArray()

// Get target meta information
Track.getTargetInfo(targetInfos)

// Deactivate tracking for first target
targetInfos[0].ignore = true

// Specify that "TRACK_IMAGE_000" is static in the scene
targetInfos[0].mStatic = true;

// Apply target meta information
trackingFramework.setTargetInformation(targetInfos)

Changing any other property of the target meta information will not affect the framework.

Get 3D Model data

In case a CAD model is used as a target, the 3D mesh information of this model can be loaded from the framework:

// Pre-initialize CAD model instance
var cadModel = Common.CADModel()

// Retrieve model information
Track.getCADModel(cadModel)

The returned CADModel contains the vertex data and vertex IDs, which can be used for visualization of the tracked model.

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Retrieve Image from Image Source

You can retrieve a shallow copy of the latest processed image as an RGBA ByteBuffer for visualization purposes.

// Get last processed image as ByteBuffer
val RGBAImage = Track.getFrame()

Use a File Sequence as Image Source

For development and debugging purposes, the Track framework can also be used with a file sequence instead of camera input. Therefore the path to the file sequence needs to be specified before calling the initialization method.

// Set file sequence path before initializing Track framework
Track.setFileSequencePath("/sdcard/fileSequence/")
Track.initialize(context)

When the file sequence is active, the camera does not invoke the processing methods. Since the process or processWithCallback method should not be called on UI/Main thread, a separate thread is needed:

Thread {
    while (Track.processWithCallback()) {
        SystemClock.sleep(16) // Limit to 60 FPS
    }
Log.e(TAG, "File sequence finished")
}.start()

Record a file sequence

VIRNECT Track provides the functionality to record a file sequence. The startRecording method needs to be called when the framework is initialized and already running. It takes the path to save the images as a first parameter and a boolean flag to choose between JPG and PGM format as a second.

fun toggleRecording(){
    if(Track.isRecording())
        Track.stopRecording()
    else
        Track.startRecording("/sdcard/recording/",false) // Record JPG images
}

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Use the map recorder

To record a Map target, the map recording mode needs to be enabled before the initialization of the framework. To initialize the recording, one image target needs to be set as well. Once the recording is finished, the map can be saved by calling saveMapTarget.

// Enable map recording
Track.enableMapTargetGeneration(true, "mapTargetName", targetDataPath)

// Set Image target for initialization
Track.setTargetNames(arrayOf("ImageTargetName"))

// Initialize framework
Track.initialize(context)

// Listen for user interaction to save map target
saveMapButton.setOnClickListener { Track.saveMapTarget() }

Get 3D Map points

To visualize Map targets, the tracked 3D points can be loaded from the framework. To reduce the amount of data retrieved with this command, the version of the Map should be checked beforehand. When the Map data updates internally, the version number will be increased.

// Save latest retrieved version
var lastRetrievedVersion = 0;

void renderMap(){
    // Check MAP data version
    val currentVersion = Track.getMapPointsVersion(targetName)
    if( currentVersion > lastRetrievedVersion){

        // Update version
        lastRetrievedVersion = currentVersion;

        // Retrieve tracked MAP points
        val points:Common.Vec3[] = Track.getMapPoints(targetName)

        // Visualize points
        ...

    }
}