骨骼跟踪，未将对象引用设置到对象实例

Question

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using Microsoft.Kinect;

namespace 挥手识别
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        Skeleton[] skeletons;
        Skeleton k;
        KinectSensor _kinect;
        public MainWindow()
        {
            InitializeComponent();
        }
        public void StartKinect()
        {
            if (KinectSensor.KinectSensors.Count>0)
            {
                _kinect = KinectSensor.KinectSensors[0];
                if (_kinect.Status == KinectStatus.Connected)
                {

                    _kinect.ColorStream.Enable(ColorImageFormat.RgbResolution640x480Fps30);
                    _kinect.SkeletonStream.Enable();

                    _kinect.ColorFrameReady += _kinect_ColorFrameReady;
                    _kinect.SkeletonFrameReady += _kinect_SkeletonFrameReady;

                    _kinect.Start();

                }
                else
                {
                    MessageBox.Show("请链接KINECT");
                }

            }

        }

        public void LeftHandUp()
        {
            MessageBox.Show("左手上举");                 //挥动左手弹窗提示
        }
        public void RightHandUp()                          //挥动右手弹窗提示
        {
            MessageBox.Show("右手上举");
        }

        void _kinect_SkeletonFrameReady(object sender, SkeletonFrameReadyEventArgs e)
        {
            bool isSkeletonReady = false;
            using (SkeletonFrame frame =e.OpenSkeletonFrame())
            {
                skeletons = new Skeleton[frame.SkeletonArrayLength];
                frame.CopySkeletonDataTo(skeletons);
                isSkeletonReady = true;

            }

            if (isSkeletonReady)
            {
                Skeleton currentskeleton = (from s in skeletons
                                            where s.TrackingState == SkeletonTrackingState.Tracked    //追踪骨骼存入skeletons中
                                            select s).FirstOrDefault();
                if (currentskeleton != null)
                {

                    Joint LeftHand = k.Joints[JointType.HandLeft];
                    Joint RightHand = k.Joints[JointType.HandRight];
                    Joint ShoulderLeft = k.Joints[JointType.ShoulderLeft];
                    Joint ShoulderRight = k.Joints[JointType.ShoulderRight];

                    if (LeftHand.Position.Y > ShoulderLeft.Position.Y)
                    {
                        RightHandUp();
                    }
                    if (RightHand.Position.Y > ShoulderRight.Position.Y)
                    {
                        RightHandUp();
                    }
                }

            }
         
        }

        void _kinect_ColorFrameReady(object sender, ColorImageFrameReadyEventArgs e)
        {
           using (ColorImageFrame frame = e.OpenColorImageFrame())
           {
               Byte[] pixels = new Byte[frame.PixelDataLength];
               frame.CopyPixelDataTo(pixels);
               Camera.Source = WriteableBitmap.Create(frame.Width, frame.Height, 96, 96, PixelFormats.Bgr32, null, pixels, frame.Width * 4);

           }
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            StartKinect();
        }
    }
}

小弟接触C#和KINECT刚刚一个月，很多地方都不明白，请指教

Answer 1

Hi，从你的代码来看，”Skeleton k;“这个变量一直没有初始化就在_kinect_SkeletonFrameReady函数里面被使用了，所以会产生”未将对象引用设置到对象实例“错误，请在正确的地方完成Skeleton的初始化即可。

Answer 2

楼上说的对，变量k没有被初始化。

Skeleton currentskeleton = (from s in skeletons
                                            where s.TrackingState == SkeletonTrackingState.Tracked    
                                            select s).FirstOrDefault();//追踪骨骼存入skeletons中

这句话，应该将查询的结果直接赋值给k即可。

k= (from s in skeletons
                                            where s.TrackingState == SkeletonTrackingState.Tracked    
                                            select s).FirstOrDefault();//追踪骨骼存入skeletons中

判断的时候判断k!=null