Here is a simple app describing AR (Augmented Reality). This app will simply display the view shown by the device camera and when user tap on the screen, the respected coordinates will be shown on an alert message.

CODE BLOCK :
 
//Define the current window
var currentWin = Ti.UI.currentWindow;
 
//Define overlay view which will have all the UI controls for this window.
var myOverlayView = Ti.UI.createview({
      width            : Ti.Platform.displayCaps.platformWidth,     //Asign with as device screen width
height : Ti.Platform.displayCaps.platformHeight //Asign with as device screen height
      top               : 0
});
 
//Event to show the coordinates
myOverlayView.addEventListener('click' function(e){
 
      //Show the coordinates
      alert(' X : ' + e.x + ' , Y : ' + e.y);
 
});
 
//Define the camera to show background
Ti.Media.showCamera({
 
            //On success
  success:function() {},
 
            //On cancel
  cancel:function() {},
 
            //On error
  error:function() { },
 
            //Assign the view to display over camera
  overlay:myOverlayView,
           
            // To hide system control
  showControls:false,
 
            // Don't auto-hide
  autohide:false     
});
 
NOTE : Tested on Android device