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Unformatted text preview: IS BASICS – USING MOTIONLAB
Open the video analysis application by
clicking the icon labeled MotionLAB
located in the PhysLab folder on the
desktop. You should take a moment to
identify several elements of the program.
As a whole the application looks
complex, once it is broken down it is
easy to use.
The application will prompt you to open
a movie (or previously saved session) as
shown here. The upper left corner displays a dialog box with instructions for each step during your movie
analysis. To the right of the video screen is the progress indicator. It will highlight the step
you are currently performing. Below the video display is the Video Controls for moving within your AVI movie. The slider
bar indicating the displayed frame can also be used to move within the movie. Directly to
the right of the Video Controls is the Main Controls. The Main Control box is your primary
session control. Use the Main Control buttons to navigate back and forth through the steps
shown in the progress box. The red Quit Motion Lab button closes the program. 213 APPENDIX: SOFTWARE During the course of using MotionLAB, larger resolution screens pop up to allow you to
calibrate your movie and take data as accurately as possible. The calibration screen has an
instructions box to the right of the video with Main Controls and Video Controls directly
below. The calibration screen automatically opens once an AVI movie has been loaded. 214 APPENDIX: SOFTWARE The data acquisition screen appears onlyafter you enter predictions (the progress indicator
will display which step you are at.) More will be said about predictions in a bit. The data
acquisition screen has the same instructions box and Video Controls, along with a Data
Acquisition Control box. The Data Acquisition controls allow you to take and remove data
points. The red Quit Data Acq button exits the data collection subroutine and returns to the
main screen once your data has been collected. The red cursor will be moved around to take
position data from each frame using your mouse.
Be careful not to quit without printing and saving your data! You will have to go
back and analyze the data again if you fail to select Print Results before selecting Quit.
There are just a few more items to point out before getting into calibration, making
predictions, taking data and matching your data in more detail. To the right the picture
shows the equation box for entering predictions and matching data. Directly above this and
below the progress indicator you have controls for setting the range of the graph data and
controls for printing and saving. The graphs that display your collected data are shown on
the next page. Your predictions are displayed with red lines; fits are displayed with blue
lines. 215 APPENDIX: SOFTWARE CALIBRATION
While the computer is a very handy tool, it is not smart enough to identify objects or the sizes
of those objects in the videos that you take and analyze. For this reason, you will need to
enter this information into the computer. If you are not careful in the calibration process,
your analysis will not make any sense.
After you open the video that you wish to analyze the calibration screen will open
automatically. Advance the video to a frame where the first data point will be taken. To
advance the video to where you want time t=0 to be, you need to use the video control
buttons. This action is equivalent to starting a stopwatch.
When you are ready to continue with the calibration, locate the object you wish to use to
calibrate the size of the video. You must do your best to use an object that is in the plane of
motion of your object being analyzed. At times the object under motion can be used, but
often placing an additional object in the plane of motion is required.
Follow the direction in the Instructions box and define the length of an object that you have
measured for the computer. Once this is completed, input the scale length with proper units.
Read the directions in the Instructions box carefully.
Lastly, decide if you want to rotate your coordinate axes. If you choose not to rotate the axes,
the computer will use the first calibration point as the origin with positive x to the right and
positive y up. If you choose to rotate your axis, follow the directions in the Instructions box
very carefully. Your chosen axes will appear on the screen once the process is complete. This 216 APPENDIX: SOFTWARE option may also be used to reposition the origin of the coordinate system, should you require
it, however it might be best to start completely over.
Once you have completed this process, select Quit Calibration.
This video analysis relies on your graphical skills to interpret the data from the videos.
Before doing your analysis, you should be familiar with the Review of Graphs and
Accuracy, Precision and Uncertainties appendices..
Before analyzing the data, enter your prediction of how you expect the data to behave. This
pattern of making predictions before...
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This document was uploaded on 02/23/2014 for the course MANAGMENT 2201 at University of Michigan.
- Spring '14