“Tracker is a free video analysis and modeling tool built on the Open Source Physics (OSP) Java framework. It is designed to be used in physics education.”

Workshop details

Event: ICTLT 2012

Date: 30th March 2012 (Friday)

Time: 8:30 am to 9:30 am

Venue: MR305, Suntec Convention Centre

Link: http://tinyurl.com/Tracker-ICTLT12

Why video analysis in Physics? How to use in lesson?

Important information on Tracker

  • Straightforward technical stuff on the software can be found at here.
  • Internet help can be accessed from here.
  • Installation file can be downloaded (Win, Mac, Linux). The installation file includes some videos. Further mechanics videos are found here.
  • For deployment without raising a change request or TA, download an older stable version (4.05) and put on your desktop. As long as the Java Runtime is version 1.5 (1.6 for Mac) and above, it should work nicely.
  • Professional development videos (video 1, video 2)
  • Resources from Loo Kang under OSP (Resource 1)
  • There are many schools who are using Tracker in multitude of ways. Loo Kang (ETD) and Tat Leong (RVHS) were among the pioneers in Singapore schools. Loo Kang’s blog (http://weelookang.blogspot.com/) on use of open source tools is rich in information and lesson ideas, do make a bookmark on your browser 🙂

How to film videos for Tracker

If you like to film your own videos for students to use in Tracker or you would like your students to film some phenomena for a project, please instruct them the following:

  • Any video camera or digital camera capable of filming decent resolution videos can be used. The better the visual quality of the object being tracked, the easier it can be used in Tracker.
  • The output format should be the in the format available in major OS such as mov/avi/mp4/wmv.
  • A visible standard length (a metre rule, measuring tape, etc) serves as a reference for Tracker to determine the position of the object. It must be placed parallel to the plane of motion of the object and if possible it should lie along the same plane or very close to it to avoid parallax.
  • The camera must have its sensor parallel to the plane of motion of the object. It should not be too close to minimise the error due to lens distortion.
  • The camera should not be panned (shift left or right) or moved or zoomed during the entire filming process.
  • For high speed camera footage, it should be indicated at the opening frame of the video. User should check the video setting in Tracker to determine that the framerate setting matches the video.

Material for sharing

Physics of Sports

Does the birds in the game Angry Bird obey the law of physics?

Angry Bird video (mov, motion tracking file, motion modelling file) – The video is recorded on my mac using airplay from my iPad. There seems to be some frame drop. Recommended time step to use for analysis is 3 or more.

To record the game as a movie file for tracker, you will need to be able to stream your iPhone/iPad game to your mac (yes mac only). Do plan out what you want to record.

  • You will need to buy the ReflectionApp for your mac which will set you back by USD14.99.
  • Fire up your mac Reflection App and set your iPhone/iPad to airplay to your mac. Enter the full screen mode on your mac.
  • Run Quicktime Player, select “New Screen Recording” and quicktime player. Start your recording and switch to the Reflection App.
  • After you are done recording, switch back to Quicktime Player and stop the recording. You will need to trim the video (Command + T).
  • Export your video as 480p or 720p in .mov format (higher resolution is not recommended because the resulting clip is very large. However it is really your choice in this matter)
  • Check that the birds are flying without pause, otherwise I would suggest you recommend your students to analyse the video in frame steps of 3 or more instead of just 1.

Spectroscopy with Tracker

Reference points on spectroscopy videos found on Tracker website – 543.5 nm and 632.8 nm.

Read the article by Douglas Brown for more information such as creating the images/videos for spectroscopy.

Possible questions you may pose to your students

  • Why do objects lit by fluorescent lamp appear green on camera?
  • What elements are present in our sun?

Mercury spectrum

Fluorescent spectrum

Training material for your school

Instructions (pdf version, word version) to guide you through the basic functionalities of Tracker (screen captures are from version 4.62, however almost all info should be fine in the slightly older version of Tracker). The video used in the worksheet can be downloaded from here (372kb).

If you want to conduct a similar activity with your students, you may want to use the following resources:


Your feedback is important for the workshop to be more constructive in the future. Thank you.