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AltitudeReferenceSystem Enum


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

public enum class AltitudeReferenceSystem
/// [Windows.Foundation.Metadata.ContractVersion(Windows.Foundation.UniversalApiContract, 65536)]
enum class AltitudeReferenceSystem
[Windows.Foundation.Metadata.ContractVersion(typeof(Windows.Foundation.UniversalApiContract), 65536)]
public enum AltitudeReferenceSystem
var value = Windows.Devices.Geolocation.AltitudeReferenceSystem.unspecified
Public Enum AltitudeReferenceSystem

Windows requirements

Device family
Windows 10 (introduced in 10.0.10240.0)
API contract
Windows.Foundation.UniversalApiContract (introduced in v1.0)
App capabilities


Ellipsoid 2

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

Geoid 3

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

Surface 4

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 1

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

Unspecified 0

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.

Applies to