Altimeter X 3.1

The iOS/GPS altitude measurement is derived from the device's location services. While it generally performs adequately across various environments, it exhibits limitations in detecting small altitude changes and may provide unreliable readings indoors.

Barometric altitude, available on iPhone 6 and later models, utilizes the device's built-in barometer, a common hardware approach for measuring elevation. This method can detect minute relative altitude variations; however, it necessitates calibration with external weather data or GPS information. Weather-based calibration involves retrieving current sea-level pressure and temperature from a nearby weather station, whereas GPS calibration uses the current iOS/GPS altitude as a reference point before tracking changes via the barometer.

The elevation database method provides surface elevation data by querying an external database based on your geographic coordinates. It remains effective even with imprecise location input but depends on network connectivity. The surface elevation information typically includes the height of buildings and trees at your location.