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Using Noise in Video Input

[1 Reply]
- 10-Apr-2011 04:01 PM
- Forum: Core Library Questions
Hi all,

I am trying to use a webcam to detect movement. The code I have now generates a black screen, and when the viewer moves in front of the webcam, the parts of their body that move turn white on a frame-by-frame basis (meaning only when the viewer is moving, the white frames don't stay there).

I am trying to generate abstract shapes based on the viewer's movement through the noise() function, but do not know the best way of going about this. Here is the code I have so far (partially taken from Daniel Shiffman's book, and partially from alexkwolfe.com:

// From Daniel Shiffman's Processing - Chaper 16

// Class Code for Wednesday April 6

import processing.video.*;

Capture video;

PImage previousFrame;

float diff, threshold;

int loc;

float yOffset = 0;

float noiseScale=0.02;

float noiseVal;

float perlinStep = 0.00;

float STEP = 0.02;

void setup()

{

   size( 640, 480, P3D );

   video = new Capture( this, width, height, 30 );

   previousFrame = createImage( video.width, video.height, RGB );



   threshold = 120;



   rectMode( CENTER );

  textAlign( CENTER, CENTER );

  textSize( 14 );

}

void draw( )

{

  makeWaves();

  yOffset = ((yOffset+1)%height);

  if (video.available())

  {

   previousFrame.copy( video, 0, 0, video.width, video.height,

   0, 0, video.width, video.height );

   previousFrame.updatePixels( );

   video.read( );



  } else {



  }



  loadPixels();

  video.loadPixels();

  previousFrame.loadPixels();



  for( int x = 0; x < video.width; x++)

  {

   for( int y = 0; y < video.height; y++)

   {

   loc = x + y*video.width;

   color current = video.pixels[loc];

   color previous = previousFrame.pixels[loc];



   float r1 = red(current);

   float g1 = green(current);

   float b1 = blue(current);

   float r2 = red(previous);

   float g2 = green(previous);

   float b2 = blue(previous);



   diff = dist( r1, g1, b1, r2, g2, b2 );



   // this colors the part that moves from one frame to another



   if ( diff > threshold )

   {

   pixels[loc] = color( 255 );



   }

   else

   {

   //pixels[loc] = color( 0 );

   }

   } // end inner for loop

  } // end outer for loop

  updatePixels();

}

void makeWaves()

{

background(255);



// background(0,0,30); //refresh background to erase previous pixel draw

   //move vertically down the screen

  for(float y=0; y < (height); y=y+1.5)

  {

   perlinStep = perlinStep + STEP;

   noiseVal = noise( (perlinStep+y)*noiseScale,

   (perlinStep+y)*2*noiseScale,

   y*noiseScale);

   //step through perlin noise space to get distinct waves

   for(int x=0; x<(width/2); x=x+1)

   {

   // generate the perlin value

   noiseVal = noise( (perlinStep+x)*noiseScale,

   (perlinStep+y)*2*noiseScale,

   y*noiseScale);







   stroke(255-(noiseVal*255), 10);

   point(mouseX + x*2, mouseY +(yOffset+(mouseY+noiseVal*80)), y*noiseVal*5);



   }

  }

}

Thanks for any help you can give!

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