From, Running tips
Jump to: navigation, search

High Speed Video Analysis

3,259 bytes added, 20:43, 22 January 2017
no edit summary
[[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, there the latest smartphones are a number quite capable and the software is freely available. I'll focus on using the Kinovea software, though I'll look at some of options for relatively inexpensive cameras with this abilitythe mobile apps in the near future.  =Cameras with High Speed VideoEquipment={| class="wikitable"! =Camera==! Resolution! Pixel Count! Resolution|You'll need a camera capable of recording high-| rowspan="3"|[http://wwwspeed video at a reasonable resolution.amazonIn the past, I've used a GoPro, but their fisheye distortion is a less than Casio EX-ZR100] The iPhone 6 & 7, and the Samsung Galaxy S7 will all record HD ($3601280x720)Casio EX-ZR10| 432 x 320| 138.2K| at 240|-| 224 x 160| 35.8K| 480|-| 224 x 64| 14.3K| 1000|-| rowspan="4"|Casio EX-ZR1000Casio EX-ZR700Casio EX-ZR400[ Casio EX-ZR300] Frames Per Second ($369FPS)[http://www, which is eight times as fast as typical video. I found that this resolution and frame rate is perfectly adequate for analyzing a runner.amazonUsing a lower frame rate and a high resolution did not produce as good found that using the zoom lens on my iPhone 7+ from further away produced better results than the wide-Exilim-Ex-zr200-Digital-Ex-zr200we/dp/B006596OUA Casio EX-ZR200] ($320)Casio EX-ZR20Casio EX-ZR15| 640x480| 307angle lens, as there is less perspective distortion.2K| 120|-| 512x384| 196You'll also need a tripod and an adapter for your phone.6K| 240|I'm lucky enough to have a professional grade, heavy-| 224x160| 35duty tripod, but something far simpler should suffice.8K| 480|-| 224x64| 14I purchased a cheap tripod adapter and Bluetooth remote control at the same time.3K| 1000|-| rowspan(<jfs id="B00PMDSEXK" noreferb="2true"|[ Nikon J1] ($400)| 640 x 240| 153.6K| 400 (5 second max)|-| 320 x 120| 38.4K| 1200 (5 second max)|-| rowspann="3Tripod adapter and remote control"|[ GoPro Hero3 Black Edition] ($400>) | 1280x960| 1228.8K| 100|-| 1280x720| 921.6K| 120|-| 848x480| 407K| 240|-| [ GoPro Hero3 Silver Edition] ($300)| 848x480| 407K| 120|} =Camera Recommendations=Treadmill==There are pros and cons It should be perfectly possible to the various cameras. * Ivideo a runner outside, but you've used the Casio cameras ll only get a small number of timesstrides, and they are easy it can be tricky to use and work wellanalyze the motion as effectively as you can when recording on a treadmill. The resolution and quality main downside of a treadmill is that most runners have a slightly different running form compared with running outside. Ideally, you want a treadmill that doesn't have a side rail that gets in the way of the camera's view of the higher frame rates it too poor to be runner. This is mostly an issue with measuring movement of much usethe hip from the side, so donit't expect to be able to use the 1000 fps modes not a huge deal. * You can sometimes get [ Kinovea software tracks motion using visual markers.ebayThese markers should be round, as the software doesn't understand a rotating, if you put a red square on your ankle, as that square turns with your leg movement, the software will lose track.html%3F_from%3DR40%26_nkw%3Dcasio%2Bexilim%2Bhigh%2Bspeed%26_sop%3D1 used High Speed EXILIM cameras You also want the marker to be on ebay] for a reasonable costplain background that has good contrast with the marker.* The Nikon J1 I've used ping-pong balls attached to black running tights with sticky tape which provides high contrast and the spherical ping-pong ball looks the same to the camera even if there is crippled by its 5 second maximum record timesome twisting motion.* The GoPro For my upper body, I use a good frame rate white, long-sleeved compression top and I'm experimenting with various markers. I've found that a round piece of tape can work, but the twisting of my upper body can rotate the marker too much. Tracking motion on shoes is a nice resolutionlittle trickier, as most shoes have complex patterns. I put some black tape over a mostly black shoe, and glued on ping-pong balls which worked reasonably well . I'll add more details as a WiFi remote control* There I try different markers. My aim is no LCD screen for replay of to track the video on the GoProforefoot, heel, ankle, knee, hip, shoulder, wrist, so you need to by the [http://wwwand LCD Screen] for $80As I experiment more, I'll give some feedback on what markers are most useful.  =Evaluating the video=Room==The simplest approach is room you use to step through take the video frame by framemeasurements is surprisingly important. It's critical you have lots of light, which so that the cameras shutter speed is possible with many software video playersfast enough to freeze the motion. For a more detailed analysis You also need enough distance between the treadmill and where you can extract each frame into a separate photo file using set up the free open source software [http://wwwcamera that you're not getting perspective FFMpeg]. You can use A plain background behind the following command to extract separate imagestreadmill is best, but though you probably want can get the software to extract work against a short relevant clip before you run this command or you will end up with too many image files to handlevisually noisy background. ffmpeg -i input(Some functions, like tracking angles, may not work quite right.avi -f image2 image-%4d.jpegWhere:* Input) The room should also have a fairly solid floor, so that the running doesn't balance the camera.avi is the name Adding something of your input video file* image-%4d.jpeg is a known size into the name of frame at the output files, with %4d replaced by same distance as the frame numberrunner can help calibrate size. =Sample OutputRecording =Below are four consecutive frames from It's worth spending a recording at 120 fps little time to get the camera positioned correctly. You want the runner to give a sense fill most of the frame so that you're not wasting resolution . If you want to evaluate the runner with the treadmill at an incline, don't forget to allow for this when positioning the camera. You want the camera positioned perpendicular to the runner, and timing as level as possible. Ensure the camera has the near edge of the available video from treadmill in view so that it can see each foot strike. I used a Casio camera. These pictures look identical on first glanceBluetooth remote control to record my running, but there is slight movement visible and I'd recommend using the remote control even if you rapidly swap between have a friend helping you. You don't want to touch the imagesphone when starting and stopping recording as any camera shake will cause problems. {| class="wikitable" |I'd recommend recording several relatively short clips (~30 seconds), as high- valign="top"|[[File:HSVA-Sample-0413speed video takes up a lot of memory.jpg|none|thumb|x300px]]|[[File:HSVA-Sample-0414.jpg|none|thumb|x300px]]|[[File:HSVA-Sample-0415.jpg|none|thumb|x300px]]|[[File:HSVA-Sample-0416The more powerful your PC, the longer the segment you'll be able to process.jpg|none|thumb|x300px]]|}  =Automated Analysis SoftwareEvaluation=I am hoping Kinovea is fairly easy to write some software that will perform some automated analysisuse, and there's a good online help section. Here are my current thoughts on the algorithm That said, there's a few caveats that could you should be used. * Capture:** Shoot aware of, so that let me walk you through the runner is shown from the waist downprocess.** Use good light If you recorded your video in portrait mode, you'll need to ensure a fast shutter speedrotate it before importing into Kinovea.** The runner should be against a relatively plain background, I used "Rotate & Flip" on flatthe iPhone prior to transferring it, level groundwhich worked okay. ** Put markers on Hopefully the runner over next version of the hipKinovea will understand rotated video, knee, ankle, heel and forefootas this is a pain.* Processing:** Scan The next step is to transfer the videoto your PC. I used Dropbox, extracting each framebut there are many other solutions.*** This may be I'd recommend using the trickiest partexperimental version of Kinovea 0.8.25, as working with video in code is rather nasty. ** Scan each frame to detect the five markers it has some nice additional functionality, and reduce them appears to the x/y coordinatesbe completely stable.** For each set of five markers, identify the body positionsDownload from [http:*** The hip will be the highest//www.*** The knee will be next]*** The forefoot will be furthest away first time you start up Kinovea, I'd recommend changing some of the remaining threepreferences. (Options menu, then select preferences.) *** The heel and ankle can be found based Click on drawings, then the tracking tab. I find setting the angle between then object window to 30x30 pixels and the forefootsearch window to 90x90 pixels is a good starting point. The default uses a percentage of the overall video window and is too big, causing tracking problems.** Find If you have a powerful PC, click playback, then the frames that represent the first contactmemory tab. This will be Increase the first frame where either the forefoot or heel ceases working zone to 30 seconds and memory to move1024 Mb.*It's fairly obvious how to open your file.* Find the frames that represent the last contact. This will be the The first frame thing to do is to adjust playback speed so that follows first contact where both you're playing the forefoot and heel are video in slow motion.** For There is a slider bar just above and right of the playback buttons, so slide this to the first contact frame:left to slow things down. *** Measure You normally set up a "working window" as a subset of the angle video clip. For performance, only a small subset of the heel/forefoot line to estimate strike angle and therefore strike index. This video can be categorized loaded into FFSmemory for analysis. Play video, MFSor click on the main timeline to choose your starting point, RFSthen click the "[" button to mark the start. Likewise, at the end of your chosen section use the "]" button.*** Find To track movement, moved to the horizontal distance from 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 foot to the hip to check for [[Overstriding|overstriding]]mouse wheel. *** Look at Once you'd set your track point you'll see two concentric rectangles and a small cross. The cross marks of the angle between center of the hip/knee object being tracked, and the knee/ankle to determine how straight inner rectangle should surround your marker, with a little bit of the leg background included. The larger rectangle isthe search window. A straighter leg may indicate a higher impact force. ** Evaluate For each frame, the software looks for the image in the small rectangle within the frames between first and last contact:*** Determine if area defined by the heel touches down at any pointlarger rectangle. This can further categorize FFSGetting these areas right is critical to successful tracking.*** Look at If you right-click near the change in knee angle cross and select "configuration…" You'll get a dialogue that will allow you to see how tweak the landing force is absorbed. ** Evaluate size of the frames between two first contact points:*** Measure rectangles.<br/>[[CadenceFile:KinoveaConfigure.jpg|none|thumb|400px|]].*** Measure If you click play, or frame advance, you'll see the line made by the marker recorded on the playback window. If the contact timeline 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 float timesearch window. Tweaking these can often, and the ratio between but not always resolve the twoproblem. *** Try Within the configuration window, you can also set the software to display a metric such as acceleration, speed, etc. You can use this to determine paw back from the maximum horizontal distance from frame with the midfoot to highest acceleration, or the hip slowest speed, or whatever else it is you're interested in. For instance, tracking vertical acceleration of a torso marker and looking for the frame with the maximum value would tell you when the horizontal distance at contactgreatest landing forces are likely to be. *** Try to determine There is another option on the probable horizontal speed of configuration dialog called "display rotation circle." This will show the foot at contactcircle around which a market is moving.*** Try You can measure angles by clicking the angle icon and then clicking on the video window. You then move the three points so they line up with the joint you're trying to evaluate measure, and it will display the angle. With the peak deceleration experimental version, you can right click on one of the hip on landing to determine impact forcespoints and select "track path" and the software will track the three markers, showing the changing angle as things progress. ** Output metrics and possibly key images The problem I found with overlays of this functionality is that you can't tweak the angles object and linessearch windows for each point, so it easily gets confused unless you have a really clear marker.

Navigation menu