AltitudeReferenceSystem AltitudeReferenceSystem AltitudeReferenceSystem AltitudeReferenceSystem AltitudeReferenceSystem Enum


Indicates the altitude reference system to be used in defining a geographic shape.

public : enum class AltitudeReferenceSystem
enum class winrt::Windows::Devices::Geolocation::AltitudeReferenceSystem : int32_t
public enum AltitudeReferenceSystem
Public Enum AltitudeReferenceSystem
var value = Windows.Devices.Geolocation.AltitudeReferenceSystem.ellipsoid;
Windows 10 requirements
Device family
Windows 10 (introduced v10.0.10240.0)
API contract
Windows.Foundation.UniversalApiContract (introduced v1)


Ellipsoid Ellipsoid Ellipsoid Ellipsoid Ellipsoid

The altitude reference system is based on an ellipsoid which is a mathematical approximation of the shape of the Earth.

Geoid Geoid Geoid Geoid Geoid

The altitude reference system is based on the distance above sea level.

Surface Surface Surface Surface Surface

The altitude reference system is based on the distance above the tallest surface structures, such as buildings, trees, roads, etc., above terrain or ground level.

Terrain Terrain Terrain Terrain Terrain

The altitude reference system is based on distance above terrain or ground level.

Unspecified Unspecified Unspecified Unspecified Unspecified

The altitude reference system was not specified.


The Terrain, Geoid, and Surface are implementation dependent and not mathematically precise.


The altitude reference system that is returned for location fixes from the geolocation API may depend on the GPS/GNSS radio hardware. Most modern hardware will provide values using the Geoid reference system, but Map Control APIs will return values in the Elipsoid system. To find out which one is being used by a Geopoint object, see the AltitudeReferenceSystem property. You should not copy a BasicGeoposition without also copying the associated AltitudeReferenceSystem, otherwise the Altitude value will not be valid and could produce unexpected results.