Kinect and WPF: Complete body tracking

It's time for a really interesting and useful Kinect tutorial. We'll see how to achieve full body tracking using Kinect sensor, OpenNI library and Windows Presentation Foundation.

I found OpenNI C# samples a little messy, so I decided to develop a .NET 4 wrapper library which could be used into WPF applications whithout requiring .NET 2 staff like GDI+, System.Drawing, etc. I named it Nui.Vision and it's part of a larger framework I currently develop. Nui.Vision is a .NET 4 assembly which offers an easy-to-use body tracking API!

Update 20/04/2011

Nui.Vision is now compatible with the latest release of OpenNI framework (1.1.0.41). I have made some changes and bug-fixes to it, including the skeleton-display fix provided by roni26_wu (see comments below). An open-source version of Nui.Vision is coming soon!

Video demo

Here is a short video I created to demonstrate complete body tracking in pure WPF (up to 6 people can be recognized). You need to stand in "Psi" position in order to start tracking:

» Download binaries and source code.

Prerequisites

• Kinect sensor or other similar device.
• Windows 7 / Vista operating system.
• .NET Framework 4.0 (version 3.5 should work, too).
• OpenNI library (installation guide - I used the unstable release).
• My Nui.Vision library.

Using the library

Using Nui.Vision is a piece of cake. All body tracking is done in the background, so you only need to update your user interface when the proper events fire. Firstly, add a reference to OpenNi.net.dll and Nui.Vision.dll. Also import a valid configuration file to your project, as described here. Do not forget to type the corresponding using statement:

[code lang="c#"]using Nui.Vision;[/code]

Then declare a new NuiUserTracker object and initialize it in the constructor. Provide the path of the configuration file you previously imported (do not forget to paste the same file in the Debug/Release folders of your application):

[code lang="c#"]_skeleton = new NuiUserTracker("SamplesConfig.xml");[/code]

Just below that, you need to define the UsersUpdated event.

[code lang="c#"]_skeleton.UsersUpdated +=
          new NuiUserTracker.UserListUpdatedHandler(Skeleton_UsersUpdated);[/code]

A proper event handler is created. The NuiUserEventArgs parameter provides you with a collection of all the recognized users! You can now get the coordinates (X, Y and Z) of every body part of every user (OpenNI currently supports 15 body parts)!

[code lang="c#"]foreach (var user in e.Users)
{
    float headX = user.Head.X;
    float headY = user.Head.Y;
    float headZ = user.Head.Z;

    float neckX = user.Neck.X;
    float neckY = user.Neck.Y;

    // etc...
}
[/code]

Quite easy, huh?

Here is a list of all the available body parts:

• Head
• Neck
• LeftShoulder
• LeftElbow
• LeftHand
• RightShoulder
• RightElbow
• RightHand
• Torso
• LeftKnee
• LeftHip
• LeftFoot
• RightKnee
• RightHip
• RightFoot

You may now start developing cool WPF Kinect applications and games. Imagination's the limit.

» Download binaries and source code.

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