Displaying Skeletal joints as WPF Canvas, but there is problem

Question

Hello 

As i am still learning to work with Kinect in C#, i started the programming with rendering a video from Kinect, the added the code of depth image to be displayed, thus far everything works fine, the videos are displayed in image of Xaml code. Now i wanted to find a good way to display the joints "20 joins" each with its coordinate displayed. i wanted to use canvas, cause it looked straight forward in coding. 

here is what i did :

 public void SetEllipsePosition(Ellipse ellipse, Joint joint)
        {
            Canvas.SetLeft(ellipse, (320 * joint.Position.X) + 320);
            Canvas.SetTop(ellipse, (240 * -joint.Position.Y) + 240);
        }

        void nui_SkeletonFrameReady(object sender, SkeletonFrameReadyEventArgs e)
        {
            SkeletonData skeleton = (from p in e.SkeletonFrame.Skeletons
                                     where p.TrackingState == SkeletonTrackingState.Tracked select p).FirstOrDefault();

            SetEllipsePosition(HipCenter, skeleton.Joints[JointID.HipCenter]);
            SetEllipsePosition(Spine, skeleton.Joints[JointID.Spine]);
            SetEllipsePosition(ShoulderCenter, skeleton.Joints[JointID.ShoulderCenter]);
            SetEllipsePosition(Head, skeleton.Joints[JointID.Head]);
            SetEllipsePosition(ShoulderLeft, skeleton.Joints[JointID.ShoulderLeft]);
            SetEllipsePosition(ElbowLeft, skeleton.Joints[JointID.ElbowLeft]);
            SetEllipsePosition(WristLeft, skeleton.Joints[JointID.WristLeft]);
            SetEllipsePosition(HandLeft, skeleton.Joints[JointID.HandLeft]);
            SetEllipsePosition(ShoulderRight, skeleton.Joints[JointID.ShoulderRight]);
            SetEllipsePosition(ElbowRight, skeleton.Joints[JointID.ElbowRight]);
            SetEllipsePosition(WristRight, skeleton.Joints[JointID.WristRight]);
            SetEllipsePosition(HandRight, skeleton.Joints[JointID.HandRight]);
            SetEllipsePosition(HipLeft, skeleton.Joints[JointID.HipLeft]);
            SetEllipsePosition(KneeLeft, skeleton.Joints[JointID.KneeLeft]);
            SetEllipsePosition(AnkleLeft, skeleton.Joints[JointID.AnkleLeft]);
            SetEllipsePosition(FootLeft, skeleton.Joints[JointID.FootLeft]);
            SetEllipsePosition(HipRight, skeleton.Joints[JointID.HipRight]);
            SetEllipsePosition(KneeRight, skeleton.Joints[JointID.KneeRight]);
            SetEllipsePosition(AnkleRight, skeleton.Joints[JointID.AnkleRight]);
            SetEllipsePosition(FootRight, skeleton.Joints[JointID.FootRight]);
        }

and In xaml

 <Grid Height="503" Width="792">
 
        <Image Height="222" HorizontalAlignment="Left" Margin="12,12,0,0" Name="videoControl" Stretch="Fill" VerticalAlignment="Top" Width="295" />
        <Button Content="Capture" 
                Height="25" HorizontalAlignment="Left" 
                Margin="88,466,0,0" Name="buttonCapture"
                VerticalAlignment="Top" Width="104" Click="buttonCapture_Click" />
        <Image Height="201" HorizontalAlignment="Left" Margin="12,249,0,0" Name="depthSourceControl" Stretch="Fill" VerticalAlignment="Top" Width="295" />
        <Grid Margin="322,20,12,12">
            <Canvas>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="HipCenter"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="Spine"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="ShoulderCenter"/>
                <Ellipse Height="25" Width="15" Fill="yellow" Name="Head"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="ShoulderLeft"/>
                <Ellipse Height="10" Width="10" Fill="Magenta" Name="ElbowLeft"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="WristLeft"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="HandLeft"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="ShoulderRight"/>
                <Ellipse Height="10" Width="10" Fill="Magenta" Name="ElbowRight"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="WristRight"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="HandRight"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="HipLeft"/>
                <Ellipse Height="15" Width="10" Fill="Red" Name="KneeLeft"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="AnkleLeft"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="FootLeft"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="HipRight"/>
                <Ellipse Height="15" Width="10" Fill="Red" Name="KneeRight"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="AnkleRight"/>
                <Ellipse Height="10" Width="10" Fill="Blue" Name="FootRight"/>
            </Canvas>

        </Grid>

    </Grid>
</Window>

this gives a problem....without any errors

the issue is of the likes 

also if i can address the problem of displaying the coordinates just near the joint points as (x,y,z) i am not sure if i can do that or not...

thank you

Answer 1

Are you using beta sdk ?

If not you should use JointType not JointID. tha may help

Answer 2

HipCenter is null you must make sure that the joint is not null so you must initiate first

---

Thanks,
MOHAMED A. SAKR | Software Development Lead Engineer | EgyptNetwork
Please remember to click “Mark as Answer” on the post that helps you. This can be beneficial to other community members reading the thread. Also try to Vote as Helpful

Answer 3

Hello,

FirstOrDefault() will return null, when no skeleton is tracked. You need to check, if you have at least one tracked skeleton.

SkeletonData skeleton = e.SkeletonFrame.Skeletons.FirstOrDefault(p => p.TrackingState == SkeletonTrackingState.Tracked);
if (skeleton != null)
{
   SetEllipsePosition(...)
   ...
}

Best regards,
Thomas

Answer 4

thank you very much...

i wanted to also ask if possible, is there an inverse kinematics method that has been implemented. If not available in C#, how can i add C++ inverse kinematic algorithm in C# as a library.

I appreciate the help

Answer 5

where do i intiate and with what ? what i idd initially  is create a method

            

        public bool IsSkeletalViewerAvailable
        {
            get { return KinectNui.Runtime.Kinects.All(k => k.SkeletonEngine == null); }
        }

then 

i called it as follow

 void nui_SkeletonFrameReady(object sender, SkeletonFrameReadyEventArgs e)

            {
           SkeletonFrame skeletonFrame = e.SkeletonFrame;
               if (IsSkeletalViewerAvailable == true )
               {

                foreach (SkeletonData skeleton in skeletonFrame.Skeletons)
                {
                    if (SkeletonTrackingState.Tracked == skeleton.TrackingState)
                    {

                        JointID joint1 = JointID.HipCenter;
                        JointID joint2 = JointID.Spine;
                        JointID joint3 = JointID.ShoulderCenter;

: :

that's what i did...but i get that problem box as shown above....

thanks Mohammed

Answer 6

Try this

private void SkeletonFrameReady(object sender, SkeletonFrameReadyEventArgs e)
{
   using (SkeletonFrame frame = e.OpenSkeletonFrame())
   {
      if (frame == null || frame.SkeletonArrayLength == 0)
        return;
      
      Skeleton[] skeletons = new Skeleton[frame.SkeletonArrayLength];
      frame.CopySkeletonDataTo(skeletons);
      
      foreach (SkeletonData skeleton in skeletons)
      {
         if (skeleton != null)
         {
            if (skeleton.TrackingState == SkeletonTrackingState.Tracked)
            {
               //Kinect for Windows SDK
               SetEllipsePosition(HipCenter, skeleton.Joints[JointType.HipCenter]);
               //Kinect for xBox SDK
               SetEllipsePosition(HipCenter, skeleton.Joints[JointID.HipCenter]);
            }
         }
      }
   }
}

---

Thanks,
MOHAMED A. SAKR | Software Development Lead Engineer | EgyptNetwork
Please remember to click “Mark as Answer” on the post that helps you. This can be beneficial to other community members reading the thread. Also try to Vote as Helpful

Answer 7

Any updates

---

Thanks,
MOHAMED A. SAKR | Software Development Lead Engineer | EgyptNetwork
Please remember to click “Mark as Answer” on the post that helps you. This can be beneficial to other community members reading the thread. Also try to Vote as Helpful