GeodeticDatum Class
Gives the position of the Ellipsoid that models the earth in a Crs.
NuGet/Assembly: Carmenta.Engine.5.16.2.nupkg (in the CECore assembly)
Syntax
public class GeodeticDatum : ResourceObjectRemarks
A GeodeticDatum, often just called a datum, defines where a graticule (a set of meridians and parallel circles) is located on the earth. The datum has an Ellipsoid property, which represents a slightly flattened sphere that approximates the earth surface and is the basis of the graticule. The Ellipsoid object knows its own size and shape, but its position relative to the earth is specified by the DatumShift property of the GeodeticDatum. In practice, we assume that the predefined datum Wgs84 has a known position in the real world, so Wgs84 does not need a DatumShift. But when you define a new geodetic datum, you should give it a DatumShift property that can transform longitude and latitude between the new datum and Wgs84.
A GeodeticDatum object does not have any public methods, and it is useful only as a part of a Crs; see the class diagram.
Usually, coordinates are transformed automatically when a map configuration is used. But if an application needs to call explicit methods that transform coordinates, these methods can be found in the Crs class.
In the literature, a geodetic datum is also known as a Geodetic Reference System or a Terrestrial Reference System (a TRS), which is implemented by a set of control stations with official coordinates, which form a Terrestrial Reference Frame (a TRF). So a TRF implements a TRS; the distinction is rather subtle.
Inheritance Hierarchy
System.Object (not available in C#)
EngineObject
ResourceObject
GeodeticDatum
Platforms
Windows, Linux, Android
GeodeticDatum Members
The GeodeticDatum type has the following members.
Constructors
| Name | Description |
|---|---|
| GeodeticDatum | Constructs a new instance of the GeodeticDatum class. |
Properties
| Name | Description |
|---|---|
| Authority | Gets the name of an authority, which is often epsg. |
| AuthorityCode | Gets the unique code for the GeodeticDatum instance, according to the Authority, for example 6322. |
| DatumShift | Gets the datum shift that georeferences the datum. |
| Ellipsoid | Gets the reference ellipsoid (slightly flattened sphere) that represents the Earth. |
| Id | Gets the authority code as an integer. |
| IsDisposed | Gets a value that tells whether the current GeodeticDatum has been disposed. Inherited from EngineObject |
| Name | Gets or sets the name of the GeodeticDatum. Inherited from ResourceObject |
| NativeHandle | Gets the native Carmenta Engine kernel object the current GeodeticDatum represents. Inherited from EngineObject |
| PrimeMeridian | Gets the meridian with zero longitude, usually Greenwich. |
| IUserProperties.UserProperties | Gets the AttributeSet that contains the user properties. Inherited from IUserProperties |
 Wgs84 | A predefined global datum used in GPS positioning. |
Methods
| Name | Description |
|---|---|
| AlternativeDatumShifts | Overloaded. Returns a collection of alternative datum shifts for this datum. |
| AlternativeDatumShiftsForArea | Overloaded. Returns a collection of alternative datum shifts for this datum and a given area. |
| AuthoritativeAreaOfUseBounds | Gives the bounding rectangle(s) of the largest area of use for a geodetic datum, according to an authority. |
| AuthoritativeAreaOfUseCode | Gives the code for the largest area of use for a geodetic datum. |
| AuthoritativeAreaOfUseDescription | Gives a text description of the largest area of use for a geodetic datum, according to an authority. |
| AuthoritativeAreaOfUseName | Gives the name of the largest area of use for a geodetic datum, according to an authority. |
| Clone | Creates a copy of an object. Inherited from EngineObject |
| Dispose | Releases the reference to the native Carmenta Engine kernel instance the EngineObject represents. Inherited from EngineObject |
| Equals | Determines whether this instance is equal to another. Inherited from EngineObject |