Video Analysis How To
You can use the video
analysis tools to create a graphical representation of the
motion you see in a movie or picture. This is ideal for mathematically
analyzing real world events. Instead of marking one object across
frames (time) as you would in a movie, analysis of a picture allows you
to mark many points on one frame. This is useful in getting the points
along a curve, for example.
Note: A tutorial covering video analysis is
available. Choose Open from the File
menu, then look in Experiments > Tutorials
to access it. More information about video analysis is also available
on our web site at http://www.vernier.com/til/1925/.
Basic Procedure for Video Analysis
- Before you can analyze a video, you must add a movie to
your experiment file. Choose Movie from the Insert
menu, and select the movie you want to add to your page. Supported movie formats include .mp4, .mpg, and .mpeg files.
- Click in the movie
player. The video analysis
tools will appear on the right side of the movie player. A graph will
also be displayed. By default, the graph will display both the x and y
positions versus time. If necessary, resize and move the graph to a
desired position.
- Set a scale for the analysis. For this, it is important to
have something in the movie to set the distance. You could include a
meter stick in the movie to function as a reference. Click then click and drag the mouse
from one end of the reference to the other end. A pop-up dialog box
will appear. Enter the Distance and the appropriate Unit for the object
you are using. For example, for a meter stick, enter 1
as the Distance and m as the Units.
- Click .
- Click the Play button, and just before the object in the
movie begins its motion, click the Stop button. Click the Next Frame
button and advance the movie until the object is in motion.
- Move the mouse over the movie and use the cross hairs to
identify a recognizable point on the object.
- Click the mouse. A mark is left on the screen and the movie
advances one frame.
- Repeat until you have marked the point you want to analyze.
- Click the Play button to see the object move and the record
of its horizontal and vertical position displayed on the graph. Use
Logger Pro's various analysis
features (including Curve Fits)
to study the object's motion.
See Also: