How to do video capture.

  1. Open Logger Pro.
  2. Attach your camera via a USB cable.
  3. Select “Insert”, “Video capture”.
  4. A screen will pop up. Hit play on your video camera. You should see what is showing.
  5. If not, click on “Set up camera.” Select O.K.
  6. When you see what you want from the camera, click “Start Capture.” When you are done, select “Stop Capture.”
  7. Note: Video capture takes up a lot of memory. In fact, you will want to make sure that you do not try to capture more than 10 seconds, because that is the limit of the software.

Importing video.

1.  Open Logger Pro.

2.  Select “Insert”, “Movie”

3.  Browse and find your video.

Notes on shooting video

1.  Stay still. Although the natural tendency is to follow the action, it is imperative that the screen remain still during the entire event. Essentially, you are using the background as frame of reference, if you move the camera, you are resetting frame of reference mid problem. BAD.

2.  Include some visual scale reference. If you are close enough, include a meter stick in the picture somewhere. If not, try to have some other measured distance. IT IS ESSENTIAL that your visual scale reference is at the same distance from you as the object you are filming, since distance is essentially measured in pixels, and a meter stick close in the foreground takes up many more pixels (and will be “seen” as bigger) than one in the background.

3.  Back up, and use big/contrasting objects. Because the field of view of your camera is relatively narrow, you will have to back up 15m to shoot a 15m motion. As you back up, your object will get smaller and smaller. A white golf ball against a white wall will not show up.

4.  Try to place yourself at the middle of the task to avoid errors at the far end in perceived distances.


Analysis

  1. Once you get your video on the screen, you need to click on the menu on the bottom right of the picture (“enable/disable video analysis”).
  1. The 4th icon down on the right allows you to set your scale. Do this first. Click this icon, then click and drag along your scale reference. When you let go, it will ask you what that distance is supposed to be. Enter the distance and the unit.
  1. The 5th icon down on the right allows you to measure photo distance. It is a good way to check your scale. Click this button, then click and drag to measure something, say, the person in the picture standing at the same distance as the meter stick. Does that 5th grader come out to 1.4m? Great. 2.3m or 0.5m, you have a problem somewhere.
  1. Move the movie forward and back until it is just where the motion is ready to start.
  1. Click the 2nd icon down (“add point”). Click on the object you are analyzing. It should then advance the movie one frame, and you can continue to click on the object until you have completed the analysis. After clicking on the last point, make sure to click on the 1st icon “select point” to turn it off, otherwise, you will start placing points everywhere! If you get a bad point, you can “Undo” under the dropdown menu on “experiment”. However, it is easier to just start over than to redo point #2 out of 50, so keep an eye on your graph as you plot your points, and fix any bad points immediately.
  1. If you have more than one set of points to add, you will need to rewind the video to the appropriate spot, then click the 6th icon down (“Set Active Point”). You can then select “Add point series”, then “add point” and then start adding your second series as in #5 above.
  1. Once you have finished adding all your points and they look good, you can then minimize your movie window by dragging a corner of it smaller.
  1. The first thing I like to do is to go to the top toolbar and select “analyze” and then “examine”. After doing this when you move your cursor back and forth on the graph, it shows the motion on the movie, a useful tool for pointing out the V is zero at the top of the ball’s path, or that A is still -9.8m/s/s, even at the top.
  1. By clicking on the variables on the left side (Y-axis) you can choose X and/or Y positions and/or velocities for your objects. Select those you want.
  1. Double clicking on an axis will allow you to modify the scale. There is also an “autoscale” button on the top toolbar.
  1. While it does have cool features like tangents and integrals, the two most useful functions in my opinion are “stats” (min, max, mean, median and standard deviation) and “linear fit” which gives a line of best fit through the selected points. To select points, go to your graph and click and hold from the beginning of your area of interest to the end.