Tracker Video Analysis of Falling
In this assignment you will be using a video analysis program called "Tracker" to study motion. Start by downloading a copy of the program from the Tracker website:
Next you'll shoot some video reference of an object falling from a height of about 4 feet. You have to be the person in the video dropping the object. Make sure that the object is clearly visible as it falls; avoid cluttered backgrounds that make it hard to see the object when there's motion blur. Use good lighting and keep the camera fixed and steady (set it on a table if you don't have a tripod). Do not rotate the camera from landscape to portrait (i.e., don't turn it sideways) since you probably won't be able to rotate the video.
Drop the object at least five times and then analyze the best take. If your camera's frame rate is 15 fps or lower then consider using a different video camera. The higher the frame rate the easier it will be for you to analyze the video in Tracker.
Run the Tracker program on your computer and import the video clip of the falling object. You may need to convert your clip into a format that Tracker can import (either MOV or AVI), if it's not already in that format (this is unlikely).
In the "Tracks" menu select "New -> Point Mass"; a Track Control window should appear.Press the [Select Trail Length] button on the bar and select the “All Steps" option. Optional: Right click on the video to zoom in or out.
Go to the first frame in your clip that you want to analyze, hold down the shift key to change the cursor into cross-hairs, then click on the center of your object. The program will mark that position and advance one frame. Continue holding down the shift and marking the position of the object until it hits the ground (which should be after 15 to 20 frames if your camera's frame rate is 30 fps). Due to motion blur the object will visually "stretch" as it falls and it may be difficult to locate the exact center but just do your best to estimate the center of the blur.
Click on the “Choose a View” button at the upper corner of the table and switch from Table view to Plot view. Click on the “x” on the plot axis to bring up a menu; change selection to “y: Position y-component”. Your screen should look something like this:
In the "Edit" menu select "Copy Image -> Frame" to copy the whole window to the clipboard. Open your favorite graphics program, such as Paint or PhotoShop, paste the image, then save it to a file. Finally, upload that image to your blog into a post called "Tracker Video Analysis of Falling". Also upload your original reference video with all of your takes.
Here are some examples from previous semesters:
* Shoot video reference of an object falling from a height of about 4 feet; you have to be the person in the video dropping the object
* Open your video reference in Tracker and pick the best take (need at least 5 takes in your video).
* Track the falling object from about the time of release until it hits the ground. You may continue tracking bounces (optional).
* Show plots for both horizontal (x) position versus time and vertical (y) position versus time.
* Graph of vertical position versus time is roughly a parabolic arc.
* Post your screen shot in a blog entry entitled "Tracker Video Analysis of Falling"
* Also upload your original reference video with all your takes onto your blog posting.
* Complete the assignment by submitting the URL address of your blog posting using the Canvas system.
IF YOU ARE HAVING TROUBLE WITH TRACKER, LET ME KNOW ASAP!
30 points (15 points if late)
Have a question? Go here.