Close range tracking (torso), angle of body

  • Tech Staff

    So, I have a project where I need to track a body rather close.

    (waiting for dimensions), could be under 2 feet.
    So, what I need to gather is the angle of the person standing... meaning if they stand straight upright (90) if leaning to the right  (110), to the left (70).
    Any thoughts on a best approach?

    I am going to see if a kinect can be used (once I have dimensions)

    If via webcam, I should have control of the background and lighting... so I think I could threshold to BW, and test an array of video regions with 'color measure' and find the range of the head, and torso.. then calculate an angle.. but this seems like there would be a lot of noise/error.
  • Izzy Guru


    It should not be a problem with the Kinect (not sure how much of the body you see from 2 feet away and how good Kinect is from this short distance, maybe turn the Kincet 90º to get more of the body). Then calculate the angle with the x-value of the hip-center to the x-value of the neck-center.

    Best Michel

  • Tech Staff


    I think I will need to do some kinect tests. Not sure I can get a reliable skeleton that close, even with the Kinect 2.
    I haven't tried it on 90 edge.. I will report back on this.
    Are there any USB webcams that are good for IR work? I can use IR LEDs to light the background.. and workout a silhouette... maybe send out to some openCV script to get orientation.
  • Izzy Guru


    I don't know any cameras that are good for IR. Sorry.

  • Tech Staff

    I am thinking a modded ps3 eye.
    Anyone have experience with this?

  • I bought a snap on wide angle lens for my kinect. Increases the angle quite a bit!

  • Have you tried using the built in Eyes or Eyess++ actors when using a difference actor?

    I was able to very quickly set up a video in watcher->difference=>eyes  and have it easily track my shifting back and forth between standing straight and leaning to the sides. . . With smoothers and some fussing it may do what you need. 


  • Tech Staff

    Eyes is my go to.

    I need the lighting/contrast to be fool-safe, since this project will be traveling without me.
    I am going to get a PS eye, and mod it.. it seems easy and low cost.. 
    As I test it, I will post my results.
    I haven't seen these. Do you have a link to one you could share?

  • Dear @DusX,

    Could you use fiducial markers? For instance, if you had the fiducial pattern on the costume, but done it such a way that the fabric does _not_ reflect IR, and the fiducial marker _does_ reflect IR, then you could make it so that the marker was invisible (at least somewhat?) to the naked eye. The benefit to this approach is that fiducial markers give you not only position, but rotation as well.
    Here's a software that uses fiducial markers.
    Just a thought.
    Best Wishes,
  • Tech Staff

    @mark, this would be a great approach if I had control over the user, but this is meant to be open to the public to interact with.

    I am happy if I can get some basic swaying of the users body. 
    That would suit the interactive element nicely... 
    so I'm going to test Kinect and the PS eye.
    Wish me luck.

  • @DusX -- GOOD LUCK! ;-)

  • If it is just torso angle a gyro and wireless arduino would be easier imho. No tracking just real data.

  • Good luck!!! Would love to know if you figure something out that can be as robust as you need. -A

  • @DusX

    after the Werkstatt i tried to mod our ps eye but failed as there are different versions on the market, if you buy one just be aware of this difference.

  • You can take the easy way out (for searching modified PS3 eye IR camera)
  • Tech Staff


    Thanks... I had looked at this site some time back but didn't have the link anymore.
    Helpful piece of information for sure... thanks.

  • @DusX this is the one i ´m using
  • Tech Staff


    Thanks.. that cool.