As we discussed, the track.yaml file contains ROS parameters, which are required by face_tracker_node. Here are the contents of track.yaml:

    image_input_topic: "/usb_cam/image_raw" 
    face_detected_image_topic: "/face_detector/raw_image" 
    haar_file_face: 
    "/home/robot/chapter_12_ws/src/face_tracker_pkg/data/face.xml" 
    face_tracking: 1 
    display_original_image: 1 
    display_tracking_image: 1 

You can change all of the parameters according to your needs. In particular, you may need to change haar_file_face, which is the path of the haar face file (this will be your package path). If we set face_tracking:1, it will enable face tracking, otherwise, it will not. Also, if you want to display the original face-tracking image, you can set the flag here.