diff --git a/MapScript.js b/MapScript.js
index d883fe9..54e5ffa 100644
--- a/MapScript.js
+++ b/MapScript.js
@@ -1,28 +1,62 @@
 var map;
-var myLocation = {lat: 41.8077, lng: -72.2540};
+var markersArr = [];
+var myLocation = {lat: 0, lng: 0};
 
+// Map constructor
 function initMap() {
   map = new google.maps.Map(document.getElementById('map-canvas'), {
-    zoom: 13,
+    zoom: 2,
     center: myLocation,
     rotateControl: true
   });
-
-  /* var marker = new google.maps.Marker({
-    position: myLatLng,
-    map: map,
-    animation:google.maps.Animation.DROP,
-    title: 'Hello World!'
-  }); */
 }
 
-function addMarker(lt, ln, prov)
+function updateMapCenter(fileData)
 {
-  // Troubleshooting call:
-  //console.log("Latitude: " + lt + ". Longitude: " + ln);
+  var centerLat = 0;
+  var centerLon = 0;
+  var centerLatTotal = 0;
+  var centerLonTotal = 0;
+  for(var i=0; i<fileData.data.length; i++)
+  {
+    centerLatTotal += fileData.data[i].latitude;
+    centerLonTotal += fileData.data[i].longitude;
+  }
+  centerLat = centerLatTotal / (fileData.data.length);
+  centerLon = centerLonTotal / (fileData.data.length);
+  var newCenter = {lat: centerLat, lng: centerLon};
+  console.log("CenterLat: " + centerLatTotal + ". CenterLon: " + centerLonTotal);
+  map.setCenter(newCenter);
+  map.setZoom(8);
+}
+
+function addMarker(lt, ln, prov, timeMillis) {
   var location = new google.maps.LatLng(lt, ln);
   var marker = new google.maps.Marker({
     position: location,
     map: map
   });
+  if (prov == "GPS") {
+    marker.setIcon("http://maps.google.com/mapfiles/ms/icons/red-dot.png");
+  }
+  else {
+    marker.setIcon("http://maps.google.com/mapfiles/ms/icons/green-dot.png");
+  }
+  marker.provider = prov;
+  marker.timeStamp = timeMillis;
+  markersArr.push(marker);
+}
+
+
+function updateMarkers(timeStart, timeEnd) {
+  for (var i = 0; i < markersArr.length; i++) {
+    thisMarker = markersArr[i];
+    markerTime = new Date(thisMarker.timeStamp);
+    if (markerTime < timeStart || markerTime > timeEnd) {
+      thisMarker.setMap(null);
+    }
+    else {
+      thisMarker.setMap(map);
+    }
+  }
 }