My Altitude uses GPS signals to determine your current location, altitude (height from sea level) barometric pressure and water boiling point. This application does not need an internet connection and works best in outdoors. By default, it uses device sensor to determine the altitude, but you also have the option to use NOAA data files to get the altitude of your location. On newer devices, using device sensor is more accurate. It also allows you to get a picture of where you are and save it in photo album. Picture will be sealed with coordinates of current location along with altitude and local date/time. Barometric Pressure is calculated based on elevation. On newer devices such as iPhone 6/6+ value is being delivered directly from device built-in barometric sensor. Enjoy.