Tolis smith Tolis smith - 1 month ago 12
C# Question

Looking for a function for motion detection on emgucv

I am new to emgu cv; I'm trying to find a code that makes motion detection. I tried this:

CvInvoke.cvAbsDiff(frame, _backgroundImage, BgDifference);


... but I have lighting problems. I want to get white the pixels where there was motion, and then draw a rectangle there only one rectangle, but I take more areas with white pixels.

What do I need to do? Could I try ananother function?

Answer

Convert a single frame to grayscale. Convert a new frames from real time into grayscale. Make abstractions between the first frame and new frame from real time. The result of this is a third, new frame comprised of the differences between the first two. Use erosion and thresholding for that to get a frame with white representing the motioned section and black representing the rest of the space.

Here is a piece of code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Emgu.CV;
using Emgu.CV.UI;
using Emgu.CV.CvEnum;
using Emgu.CV.Structure;
using System.Diagnostics;
using System.IO;
using System.Data.SqlClient;
using System.Data.SqlServerCe;
using System.Drawing.Imaging;

namespace ptuxiakh___
{
    public partial class Form1 : Form
    {
        Capture _capture = new Capture();
        Capture capture2 = new Capture();

        Image<Bgr, Byte> FirstImage = new Image<Bgr, Byte>(640, 480);
        Image<Bgr, Byte> RealTimeImage = new Image<Bgr, Byte>(640, 480);

        Image<Gray, Byte> des = new Image<Gray, Byte>(640, 480);
        Image<Gray, Byte> thres = new Image<Gray, Byte>(640, 480);
        Image<Gray, Byte> eroded = new Image<Gray, Byte>(640, 480);

        bool baground = false;

        private void Background()
        {
            try
            {
                FirstImage = _capture.QueryFrame();
                background = true;
            }
            catch(Exception e)
            {
                baground = false;
            }
        }

        private void Tracking(object sender, EventArgs e)
        {
            if (baground == true)
            {
                RealTimeImage   = capture2.QueryFrame();

                CvInvoke.cvAbsDiff(FirstImage.Convert<Gray, Byte>(),
                    RealTimeImage.Convert<Gray, Byte>(), des);
                CvInvoke.cvThreshold(des, thres, 20, 255, THRESH.CV_THRESH_BINARY);
                CvInvoke.cvErode(thres, eroded, IntPtr.Zero, 2);
            }
            else
            {
                Background(); // At first trying to get a static frame for 
                        // abstraction with real time frame 
            }
       }

       private void StartButton_Click(object sender, EventArgs e)
       {
           Application.Idle += new EventHandler(Tracking);
       }

       private void Stopbutton_Click(object sender, EventArgs e)
       {
           Application.Idle -= new EventHandler(Tracking);
       }
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