Processing code used for http://www.flickr.com/photos/badgrs/6123213963

image_output.pde

import org.json.*;
import java.net.*;
import java.util.Iterator;

PImage bg;

JSONObject data;
double west = -3.414001;
double east = -3.017120;
double north = 56.002605;
double south = 55.882629;
double longDiff = east - west;
double latDiff = north - south;
int width = 10240;
double ratio = 0.54;
int height = (int)Math.floor((double)width * ratio);
int spotSize = 11;

/*
||******************************************************************************************
|| Read the JSON data from the web server
||******************************************************************************************
*/
JSONObject pullJSON(String targetURL) {
   String[] lines = loadStrings(targetURL);
   try {
  return new JSONObject(join(lines, ""));
   } catch(JSONException ex) {
    println(ex.getMessage()); 
    return null;
   }
}

/*
||******************************************************************************************
|| Do all the processing setup stuff
||******************************************************************************************
*/
void setup() {
   data = pullJSON("https://roryf.cloudant.com/festival/_design/output/_view/geo");

   size(width, height);
  //bg = loadImage("map-really-large.png");   
  background(0);
  noStroke();
  try {
   JSONArray rows = data.getJSONArray("rows");
   
   for (int i = 0, l = rows.length(); i < l; i++) {
     JSONObject row = rows.getJSONObject(i);
     JSONObject val = row.getJSONArray("value").getJSONObject(0);
     //println(val.toString());
     double lat = val.getDouble("lat");
     double lon = val.getDouble("lon");
     int x = (int)(((west - lon) / longDiff) * width) * -1;
     int y = (int)(((north - lat) / latDiff) * height);
     String source = val.getString("source");
     if (source.equals("twitter")) {
       radialGradient(x, y, 0xFF2AA9D4, spotSize);
     } else if (source.equals("gowalla")) {
       //radialGradient(x, y, 0xFFF79120, spotSize);
     } else if (source.equals("flickr")) {
       //radialGradient(x, y, 0xFFFF0084, spotSize);
     }
   }
  } catch(JSONException ex) {
    println(ex.getMessage());
  }
  
  save("output.png");
}

void radialGradient(float x, float y, int c, int size) {
  PGraphics pg = createGraphics(size, size, JAVA2D);
  pg.beginDraw();
  pg.background(30, 0);
  int halfsize = size / 2;
 
  for (int i = 0; i <= size; i += 1) {
    for (int j = 0; j <= size; j += 1) {
      // calculate distance to center
      //float distance = (float) Math.hypot(i - size / 2, j - size / 2) / (size / 2);
      //float distance = (float) sqrt(sq(i-size/2) + sq(j-size/2)) / (size/2);
      float xDist = i - halfsize;
                float yDist =  j - halfsize;
                float distance = (float) Math.sqrt(xDist*xDist + yDist*yDist) / halfsize;
      float scale = 1 - distance;
      if (scale < 0 ) {
        scale = 0;
      }
      float transparency = 255 * (scale * scale);
      int thisColour = color(c, int(transparency));
      pg.set(i, j, thisColour);
    }
  }
 
  pg.endDraw();
  imageMode(CENTER);
  image(pg, x, y);
}