Augmented reality
Augmented reality (AR) is the process of adding computer-generated imagery to a real-world environment. You will see it on TV where images and lines are added to sports coverage showing the distance that a cricket ball has been hit, or in football with an offside line, or American football with a line showing where the next first down will be and the distance to it. In smartphones, it's the process of adding images to the camera viewer.
This will be a simple example of AR. There is plenty more that needs to be done to make a full AR app, such as including inputs from the accelerometer and the GPS. Calculations also need to be made of pitch and distance. This is all possible with Titanium but is beyond the scope of this book. Should you need to look into this further, you should take a look at the excellent Titanium AR book Augmented Reality using Appcelerator Titanium Starter, Trevor Ward, Packt Publishing.
Note
Do not rely on this example for navigation. It is only an example...