The callback function passed here becomes the onclick handler for clicks within the AerialSphere frame.
callback (function): A callback function to execute. It will be passed an object with the following properties:
pan (number): The pan of the click event
tilt (number): The tilt of the click event
lat (number): The calculated latitude at the click event
lng (number): The calculated longitude at the click event
ele (number): The calculated altitude at the click event, measured in meters above sea level