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Getting started with the ViSP moving edge tracker
Description: How to track an object using a recorded video sequence.Tutorial Level: BEGINNER
Next Tutorial: Tracking your own model
Contents
Starting the video sequence
The package comes with a sample bag file in bag/tutorial-static-box.bag.
It stores synchronized messages for a monocular camera and its associated camera information.
You can launch rosbag replay, the tracker node and a client by typing:
# If you are using ROS Groovy or later: roslaunch visp_tracker tutorial.launch # If you are using ROS Fuerte or later: roslaunch visp_tracker tutorial-fuerte.launch # If you are using ROS Diamondback or before: roslaunch visp_tracker tutorial.launch
Setting the initial pose
The client will launch automatically and display the following image.
- You must first right-click to enter in the manual pose initialization stage, then left-click on four of the box corners in the order illustrated by the following screenshot:
- If the initial pose is satisfactory (ie. the green lines of the model match the object edges) you have to validate the initial pose with a left-click. Note that with a right-click you enter again in the previous stage where you have to left-click on the four points.
- Before validating the initial pose, you can tune the tracking parameters:
rosrun rqt_reconfigure rqt_reconfigure /tracker_mbt_client
- Finally a new left-click closes the initialization stage and start the tracker.
Monitoring the tracking
You can then monitor the tracker by running:
rosrun visp_tracker visp_tracker_viewer _camera_prefix:=/wide_left/camera
The viewer should display a result similar to this screenshot: 
To plot the object position, type:
rqt_plot topics /object_position/transform/translation/x:y:z
Fine tuning the tracking parameters
Additionally, the tracking parameters can be changed online using rqt_reconfigure:
rosrun rqt_reconfigure rqt_reconfigure /tracker_mbt
