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Tuesday, December 22, 2015

Video Analysis: A Powerful technique using video cameras of any kind, even your phone's, with Tracker software

A game changer for high school research has been the advent of decent digital cameras that are widely available and affordable, such as those on smartphones or standalone cameras purchased for $100 or less at Target or Best Buy. More and more of these cameras even have high-speed capabilities of several hundred frames per second (fps), as compared to the standard 30 fps of a general camcorder. Using video as a data collection device for any type of experiment where motion or change is occurring can allow even high school students and teachers to do a good analysis of the experiment.

Video data collection and analysis has become a standard part of my classroom labs for several years, and students quickly learn the benefits of video to enhance their datasets and analysis sections of lab reports. They embrace it on an everyday basis since it is part of their phones, and often they do this for events outside of the classroom (they want to do science and analysis on their own! Great buy-in leading up to possible research projects for your students).

Some phones, such as the new iPhones (6th generation) have settings up to 240 fps or 480 fps. They also allow for frame-by-frame viewing, where the time between frames is on order of 0.0042 sec and 0.0021 sec, respectively. This allows high school students to do an analysis where one can watch time development of the system being studied at a millisecond scale. Also, for better, fuller analysis, one can use a free software package called Tracker to analyze video or still digital photos. Download Tracker onto a school computer or your own computer, and the world of video analysis is now yours!

Below is an introductory video for Tracker, by the author of the software, Douglas Brown. A second video has an introduction of how to use the autotracking feature of Tracker. There are numerous videos on YouTube about using this type of software. Note that some schools may have Vernier's Logger Pro software, which also has photo and video analysis features. An introductory video for using Logger Pro for video analysis is here. What is so nice about these is one can calibrate distances and times within the video and make measurements right from the still frames you've captured. What you may want to do is be sure a meterstick is in the video, and/or a stopwatch. This allows you to have good calibrations whether you use Tracker or not.

Here is an introduction into Tracker software:



And now to learn how to use Autotracking features in Tracker:




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