Motion Detection with Processing & OSC

In case it’s of use to anyone, here’s the Processing code I’ve been using to detect motion in a space using a web cam, and to send that information to Max/MSP. The data is sent via Open Sound Control (OSC), so you’ll need to have installed this in Max before you start (it’s available here: http://cnmat.berkeley.edu/downloads). Although Matt Jackson tells me you can just use the UDP Receive object in Max.

The code is largely based on code supplied by Matt Jackson – http://jacksonmatt.wordpress.com/

I’ve since moved on to use a ‘blob’ detection solution, based on the Open Computer Vision framework (http://ubaa.net/shared/processing/opencv/) instead of this code – the data being sent to Max was too ‘jittery’ since it sends the location of every patch of screen area in which motion is detected, whereas what I really needed to monitor was the centre point of each person in the space, whether they’re moving or not.

Download the zip file or cut and paste the code below into Processing. 


//code to pixellate video signal and send x,y value to Max/MSP. Largely based on code by Matt Jackson (http://jacksonmatt.wordpress.com/)

import processing.video.*;  
import oscP5.*; //we need this to communicate with MaxMSP
import netP5.*; //we need this to communicate with MaxMSP

OscP5 oscP5; //variable for MaxMSP Comms
NetAddress myRemoteLocation; //variable for MaxMSP Comms

Capture video;  
PImage backgroundImage;  
PImage previousImage;


float threshold =  50; // adjust this to control sensitivity         
int g = 1; //size of gaps between blocks
int bs = 20; // Size of blocks

int gs=g+bs;

void setup()  {  
  size(600,600, P3D); 
  video = new Capture(this, width, height, 5); 

  backgroundImage = createImage(video.width,video.height,RGB); 
  previousImage = createImage(video.width,video.height,RGB); 

  background(0);    

  /* start oscP5, listening for incoming messages at port 5555 */
  oscP5 = new OscP5(this,5555);

  myRemoteLocation = new NetAddress("127.0.0.1",5555);
}   


void draw()  
{  
  background(0);



  if (video.available())  
  {  
    previousImage.copy(video,0,0,video.width,video.height,0,0,video.width,video.height);
    previousImage.updatePixels();

    video.read(); 

  }   


  loadPixels(); 
  video.loadPixels(); 
  backgroundImage.loadPixels(); 
  previousImage.loadPixels();



  for (int x =0; x < video.width; x++ ) {  
    for (int y=0; y< video.height; y++ ){  
      int loc =x + y*video.width; 

      color fgColor =video.pixels[loc]; 
      color pfColor = previousImage.pixels[loc];
      color bgColor=backgroundImage.pixels[loc]; 

      float r1 = red(fgColor); 
      float g1 = green(fgColor); 
      float b1 = blue(fgColor); 
      float r2 = red(bgColor); 
      float g2 = green(bgColor); 
      float b2 = blue(bgColor); 
      float diff = dist(r1,g1,b1,r2,g2,b2); 

      float r3 = red(pfColor); 
      float g3 = green(pfColor); 
      float b3 = blue(pfColor); 

      float diffmot = dist(r1,g1,b1,r3,g3,b3); 




      if (diff <  threshold )

      {   
        pixels[loc] = 0;

      }
      if (diffmot>  threshold)  
      
      { 
        if (loc%gs==0 &&  y%gs==0){      
          fill(0,0,brightness(fgColor));
          rect(x ,y,bs,bs);
          
          //send the pixel location to MaxMSP
          OscMessage myMessage = new OscMessage( "processing" );
        myMessage.add(new int[] {x, y}); 
 
      // send the message 
        oscP5.send(myMessage, myRemoteLocation);
        }   

      }

    }
  }
  updatePixels(); 
  
}

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