Skeltrack 0.1.10 is out

That’s right, a new version of the world’s first Free Software skeleton tracking library is out.
In every version we try to make Skeltrack more robust and this one is no exception.


We have changed the way the shoulders are inferred. This heuristic now uses a circumference around the user’s head and an arc with which it searches for the shoulders.
Since we like to keep giving developers the ability to tweak the algorithm’s parameters, we had to change the properties related to the shoulders. We should probably improve the documentation with a visual explanation of how those properties work but meanwhile you can check the properties’ documentation.

Centering Joints

Another issue we had was that the extremas we initially calculate result in e.g. the point at tip of the a finger (for a hand joint) or the top of the head. This was not an issue specifically but it might result in more unstable joints. For example, the Kinect device in particular might give blind spots in very bushy hair which would result in the head joint jittering more than usual.
To fix this, we calculate the average of points around an extrema and assign it with that value. The radius of the sphere surrounding an extrema that is used to calculate this average can be controlled by using the extrema-sphere-radius property. Thus, if this behavior is not desired, this feature can be turned off just by simply assigning a 0 to this property.

Here is a couple of pictures describing this issue:

Picture of Skeltrack's test without averaged extremas

Without the averaged extremas (extrema-sphere-radius set to 0)

Picture of Skeltrack's test with averaged extremas

With the averaged extremas (extrema-sphere-radius set to 300)

Vertical Kinect

Due to a project that Igalia Interactivity has been working on, we had to use the Kinect in a vertical stance. By doing this we discovered a small bug that prevented Skeltrack to be used with a vertical depth image. This is corrected in this 0.1.10 version and while fixing it, we found out that it seems the other skeleton tracking alternatives also do not support the Kinect in a vertical stance; this might mean that if you want to use skeleton tracking with the Kinect vertically, your only choice is either to use Skeltrack or to convince Microsoft or PrimeSense to fix their solutions for you :)

Picture of Skeltrack's test example using a Kinect in a vertical stance

Skeltrack using a Kinect in a vertical stance

Last but not least, the function skeltrack_skeleton_new was returning a GObject instance by mistake. We have corrected that and it now returns a pointer to SkeltrackSkeleton as expected.

Special thanks to Iago, our intern at the Igalia Interactivity team, for coding most of these nifty features.

Be sure to clone Skeltrack at GitHub and read the docs, you are welcome to participate in its development.

3 thoughts on “Skeltrack 0.1.10 is out

  1. Thank you (and Igalia) for hosting me and for all your help. It’s been great working with you people these months :)

  2. Hello,
    I came here via the gnome planet (or fedora planet, Don’t remember).

    I have in mind some ideas of making a sport software that is able to calculate the repetitions number done by the user on a given exercise. First I was searching in the side of OpenCV, but Skeltrak seems to be more appropriate.

    My questions is, can skeltracker recognise movements not done with the face in the camera ? I mean if, for example, the camera sees only right side of the user, and other unusual positions ? You know Recognise the user movement from different points of view and not only the frontal one.

    This is very important for a better usability if the software and user experience, but can be just optional by now.

    Thanks, Skeltrack looks very promising.

  3. Hi Dragnucs,

    The answer is no, Skeltrack currently only tracks the user if facing the camera (obviously being resistant to some rotation angle). This is the most common use case for a library like Skeltrack so we have other priorities before addressing the one you mention but of course, if you want to develop this, we are always interested in contributions.


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