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Note: Start here if you want to learn how to track an object.
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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

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.

ViSP box tracking

- 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:

ViSP box tracking

- 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: ViSP box tracking

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


2019-10-12 13:16