PImage img;
float levels = 35;                      // number of contours
float factor = 1;                       // scale factor
float elevation = 55;                   // total height of the 3d model
float colorStart =  0;                  // Starting degree of color range in HSB Mode (0-360)
float colorRange =  100;                // color range / can also be negative

// Array of BlobDetection Instances

BlobDetection[] theBlobDetection = new BlobDetection[int(levels)];

void setup() {  size(1000,800,P3D);
img = loadImage("3.gif");           // heightmap (about 250x250px)
cam = new PeasyCam(this,200);
colorMode(HSB,360,100,100);  

//Computing Blobs with different thresholds

void draw() {
  background(0);
  translate(-img.width*factor/2,-img.height*factor/2);
 
  for (int i=0 ; i<levels ; i++) {
    translate(0,0,elevation/levels);
       drawContours(i);
  }
}

void drawContours(int i)
{  Blob b;
EdgeVertex eA,eB;

for (int n=0 ;
n<theBlobDetection[i].getBlobNb() ; n++) {
  b=theBlobDetection[i].getBlob(n);
  if (b!=null) {
    stroke((i/levels*colorRange)+colorStart,100,100);      // coloring the contours 
   
    for (int m=0;m<b.getEdgeNb();m++) {
      eA = b.getEdgeVertexA(m);
      eB = b.getEdgeVertexB(m); 
      if (eA !=null && eB !=null)
      line( 
      eA.x*img.width*factor, eA.y*img.height*factor,
      eB.x*img.width*factor, eB.y*img.height*factor
      );
      }
    }
  }
 
}