public static double getMaxObservation(ArrayList<Observation>[] list, Vector2d reference){
    	if(list == null) return 0;
    	
    	double result = 0;
    	
    	for(int i=0; i<list.length; i++){
    		for(int j=0; j<list[i].size(); j++){
    			double distance = list[i].get(j).position.dist(reference);
    			if(distance > result){
    				result = distance;
    			}
    		}
    	}
    	
    	return result;
    }