// initialize the object
SrnMapType = new Object();
// image tile size
SrnMapType.tileSize = new google.maps.Size(256,256);
// max zoom on the default value
SrnMapType.maxZoom = 2;
// return the image URL
SrnMapType.getTile = function(coord, zoom, ownerDocument) {
  var img = ownerDocument.createElement('IMG');
  img.src = "assets/images/map/map_r" + (coord.y+1) + "_c" + (coord.x+1) + ".png";
  return img;
};
// tiles params
SrnMapType.name = "Tile #s";
SrnMapType.alt = "Tile Coordinate Map Type";