Track Markers

First, make sure you have calibrated your camera: read the Calibrate a Camera page. You need to have a calibration file to track some aruco objects.

Also, print and place in the environment the aruco objects you want to track. Read the Create Markers page for details.

To track your aruco objects:

• Open the Assets/ArucoUnity/Scenes/TrackMarkers.unity scene.
• Configure the camera:
  1. For a webcam, use the ArucoWebcamCalibrated object already in the scene. Otherwise, drag the prefab corresponding to your camera : Assets/ArucoUnity/Prefabs/Cameras/<CameraType>Calibrated.prefab.
  2. Fill CameraParametersFilename with the camera parameters XML file from the calibration of the camera (Fig.1).

Fig.1: ArucoWebcamCalibrated configured with camera parameters from a calibration.

• Create each aruco objects to track:
  • Configure it with what you measure on the printed aruco object. Units are in meters for tracking, not in pixels.
  • Use a ArucoObjectDisplayer to visualize the aruco object, not a ArucoObjectCreator.
  • Simply add any game object as child of the aruco object e.g. the red cube in Fig.2.

Fig.2: ArucoMarker configured to track a physical aruco marker with a 5.4 cm side length. The ArucoObjectDisplayer helps to visualize in the editor the physical object that will be tracked.

• Configure the tracker ArucoObjectsTracker:
  1. Drag all the aruco objects to track in ArucoObjects.
  2. Set ArucoCameraDisplay with the camera prefab you use (Fig.3).

Fig.3: ArucoObjectsTracker configured to track three objects for the ArucoCameraCalibrated we configured.

• Run the scene! The ArucoTracker will place (position, rotation, scale) any detected aruco object in the ArucoObjects list relative to the camera (Fig.4).

Fig.4: Roll a ball set as child of an aruco board: the game follows the board movements.

To understand the algorithm used, read this tutorial: Detection of ArUco Markers.