Video Measurement Tools

I started out doing measurements of the 9/11 videos using a tool called Physics Toolkit. More recently I have been using a much more capable and easy-to-use tool called Tracker, part of the Open Source Physics project.

Tracker allows you to mark multiple tracks with an unlimited number of points on a full-screen video, and it allows you to zoom in while placing the marks. No more magnifying glass to the screen! It also has a large collection of analysis tools. You need a little physics background to be able to use it intelligently, but no particular background to use the software.

If anyone wants to get into doing these kinds of measurements for themselves, I recommend three pieces of software (all free and downloadable):

1. Tracker, from Open Source Physics.
This is written in Java and is cross-platform. You will need to use either .mov video files or sequentially numbered jpg files. I opt for the latter.

2. To get my sequences of jpgs I use Avidemux. When you import a video into Avidemux you can check its properties with the info button. You can also set the frame rate for the output video under the video settings, for slow motion, etc. then save in a range of video formats or choose to save the video as a sequence of jpg images.

3. To do bulk processing of the still images I use Irfanview. When in the program, type "B" to get to the bulk processing option. Import the videos you want to work on, rename them, resize them, or filter them in any way you want.

There may be a bit of a learning curve but if you're interested, give it a try.

Other websites by David Chandler: lcurve.org / progressivewritersbloc.com / co.quaker.org

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