High Speed Video Analysis

625 bytes added, 11:31, 26 January 2020
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[[File:Kinovea1.jpg|right|thumb|300px|An example of the analysis from Kinovea. You can see a number of markers being tracked. The blue elbow marker has the circle of movement shown, and the knee and shoulder have acceleration displayed.]]
High Speed Video is a great way of analyzing your [[Running Form]]. While high end equipment is extremely expensive, the latest smartphones are quite capable and the software is freely available. I'll focus on using the Kinovea software, though I'll look at some of the mobile apps in the near future. I believe you can use Kinovea to evaluate [[Foot Strike]] (initial and maximum force), [[Vertical Oscillation]], [[Overstriding]], [[Arm Position| Arm Swing]], Forward lean, and Impact. I'll add details of how to do this in the near future.
* The first thing to do is to adjust playback speed so that you're playing the video in slow motion. There is a slider bar just above and right of the playback buttons, so slide this to the left to slow things down.
* You normally set up a "working window" as a subset of the video clip. For performance, only a small subset of the video can be loaded into memory for analysis. Play video, or click on the main timeline to choose your starting point, then click the "[" button to mark the start. Likewise, at the end of your chosen section use the "]" button.
* If you want to measure distances, you will need to add a line and calibrate it. Simply click on the line tool just below the video window and draw a line over your known measurement. Then right click and select "calibrate", setting the correct distance. The measure should be adjusted for the perspective difference if the known distance is offset from the thing you are measuring. * To track movement, moved to the beginning of your working window. You'll want to right click on a marker, and select "track path". It's easier to click the middle of your marker if you're zoomed in, which you do using control and the mouse wheel.
* Once you'd set your track point you'll see two concentric rectangles and a small cross. The cross marks of the center of the object being tracked, and the inner rectangle should surround your marker, with a little bit of the background included. The larger rectangle is the search window. For each frame, the software looks for the image in the small rectangle within the area defined by the larger rectangle. Getting these areas right is critical to successful tracking. If you right-click near the cross and select "configuration…" You'll get a dialogue that will allow you to tweak the size of the two rectangles. <br/>[[File:KinoveaConfigure.jpg|none|thumb|400px|]]
* If you click play, or frame advance, you'll see the line made by the marker recorded on the playback window. If the line doesn't track your marker, but jumps around, it's a sign that the software is finding a better match for your object window within the search window. Tweaking these can often, but not always resolve the problem. The first time you play after asking Kinovea to track an object it will do the analysis, thereafter it will replay the track it recorded. You can see this analyzed section of the video as a pink bar in the time window.