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High speed swing analysis camera setup

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  • High speed swing analysis camera setup

    I just finished up adding 2 high speed cameras to my garage golf sim (here's my original sim build). One cam is capturing side view and the other is capturing overhead. The swing captures trigger on the sound of the ball being hit and automatically play in slow motion on my side tv. I was able to get virtually no blurring on the club head and ball.

    Here's a look at my father in law hitting and the swing replays that got captured: https://www.youtube.com/watch?v=RVMW7QyRIvQ

    Below are the details of the setup and some lessons learned to hopefully help others...

    CAMERA SPECS
    Here's a link to the cams. The cams can do 120fps at 1280x720 or 260fps at 640x360. I found the 120fps at 1280x720 was much clearer. I went into this project thinking fps were the key to getting clear swings without motion blur, but it's not really. High fps are important for having a smooth swing to analyze in slow motion, but getting the motion blur out has to do with opening up the camera shutter speed. In theory you can get rid of motion blur at 30fps just as easily, you'd just has less frames to see so it would jump more in the video and you could miss exactly where contact is happening. I was on a budget for this part of my project so I couldn't invest in super high end cameras but these surprised me with how nice they work. The price was $75 per camera. The same camera is sold with a case but I could only find it at https://www.aliexpress.com/item/33017488541.html so I won't get those for another few weeks based on shipping times out of China.

    SOFTWARE
    I'm using Kinovea for the swing captures and replays. It's free and it's awesome! The software allows me to trigger the captures when a certain sound decibel level is reached (i.e., sound of a ball being struck). You can specify a delay as well which allows me to get the 1 second before that ball was struck and then it will automatically end the capture after a specified time (i.e. 0.5-1 second). After the swings are captured they are automatically replayed in slow motion. I bought a small lavalier mic from Amazon to run from my laptop to the hitting area to pick up the ball strike sound. It does a good job of just picking up the ball strike and not false triggering when people are talking loudly. The mic sits about 1 foot from where the ball is hit.

    I am running the camera software on a separate laptop from my gaming pc that handles the TGC2019 sim. I did this because I was worried about the captures eating up too much CPU and causing the simulator software performance to suffer. My laptop is also easier to hook up to my side tv that i'm showing the replays on. I already had this side tv mounted for watching sports games while I golf, so it was already in the perfect spot for this project.

    If you're using Kinovea, the settings I used for my overhead cam to get no motion blur were -12 exposure, full gain, ~50 brightness, ~12 contrast.

    LIGHTING
    Lighting was my biggest lesson learned. Getting clear video with no motion blur has everything to do with having enough lighting. I originally had a small 500 lumen light over my hitting area, which worked perfect in a non-camera world for my sim but no where close to workable with high speed cams. In order to reduce and get rid of motion blur I needed to open up the Exposure setting of the cams in Kinovea (I gather that's roughly equivalent to opening up the shutter speed) and that made my hitting area basically pitch black in my first video test. I needed more light, a lot more light. My worry was adding too much light and washing out the projected image on the impact screen. I came across an article from GungHoGolf and it was extremely helpful for what to do, https://gunghogolf.com/articles/indo...video-lighting. I mimic'd their setup of track lighting, building custom snoots around the lights to direct the light down and reduce light spread. I used 5 of the 3000 lumen bulbs they suggested, giving me a total of 15,000 lumens of light. I've heard other sources suggest even more lumens than that being recommended, but it worked for my purposes. Originally I tried getting similar bulbs but from a different brand from Home Depot but it was a fail. The Home Depot ones would flicker in high speed with the camera's shutter speed up. Those specific bulbs that GungHoGolf recommended were much better and don't flicker for me. The small amount of flicker I can notice in my videos appear to be from the projector light in the background, but it's fairly minimal in slow motion. The lighting cost more than I originally planned. In total it was around $250 for the track, light fixtures, lights, and misc materials for the snoots.
    TGC 2019 Published Courses:
    • Sanctuary Lake MI (L)
    • Pine Trace MI (L)
    • Deyer National Golf Club
    • Deyer Island Golf Resort
    • Sylvan Glen MI (L)

  • #16
    Anyone find a 3d print case for these cameras? Looking for the stl file so I can print.

    Comment


  • #17
    Thank you very much for the post, it is greatly useful. I followed your link and found this upgrade camera that has higher pixels and speed. Would this be too much burden for the computer? Thank you for your attention in advance. https://www.amazon.com/gp/product/B0...RHCK4F35&psc=1

    Comment


    • Olaf
      Olaf commented
      Editing a comment
      I have this one (currently looking at on with global shutter), however it has a rolling shutter which may contribute to blurring frames. Gloabel shutter is better.

      Global Shutter mode is very simple to synchronize to and often yields faster frame rates than efforts to synchronize with Rolling Shutter with the same exposure time
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