MapProjection Class

A map projection handles conversion from geographical coordinates (lon, lat) to projection coordintes (east, north) and to Euclidean 3D datum coordinates with origin in the center of the earch (center of the ellipsoid).

The ProjectionString is a WKT string for a spatial reference system. A number of abbreviated strings also exists, i.e., "UTM-33" for a WGS-84 UTM zone 33 projection.

Inheritance Hierarchy

SystemObject
DHI.ProjectionsMapProjection

Namespace: DHI.Projections
Assembly: DHI.Projections (in DHI.Projections.dll) Version: 19.0.0.0 (11.1.1.1111)

Syntax

C++

Copy

public class MapProjection

Public Class MapProjection

public ref class MapProjection

type MapProjection =  class end

The MapProjection type exposes the following members.

Constructors

	Name	Description
	MapProjection	Create and initialize a mapprojection with the specifed projection string.

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Properties

	Name	Description
	GoogleMapProjectionString	Returns the Google Map projection string
	LocalCoordinatesProjectionString
	Name	The short name of a projection. The short name is not unique amongst all WKT projections If the ProjectionString is not a WKT projection string, the ProjectionString itself is returned as the short name.
	ProjectionString	Returns the WKT projection string, or one of the projection abbreviation strings.

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Methods

	Name	Description
	AreIdentical	Function that checks if two projecions are identical. Two map projections are identical, if they have the same set of parameters. if just one of the parameters are different, then the map projections are NOT identical.
	Equals	Determines whether the specified object is equal to the current object. (Inherited from Object.)
	Geo2Proj	Convert coordinates from geographical coordinates to projection coordinates
	Geo2ProjRotation	Convert a rotation from true north into a rotation from map projection north It subtracts the convergence value from the true north rotation value The convertion depends on the geographical location.
	Geo2Xyz	Convert coordinates from geographical coordinates and height to 3D Euclidean coordinates. The 3D coordinate system origin is at the earth center (ellipsoid center)
	GetConvergence	Get the convergence (orientation towards true north) at the given geographical location. The convergence is the angle measured clockwise from true north to the north-south gridline passing through the specified coordinate.
	GetCoordSysType	Function that returns the coordinate system type. Use this function check the type of coordinate system e.g. east/north or some other combination. A typical application of this function is to exclude coordinate systems, that are not standard east/north-oriented.
	GetDefaultArea	Function that returns the default area in map projection coordinates of the projection. The default area is the area where the projection is ment to be used and where it is accurate. It is not recommended to use the map projection outside its default area.
	GetHashCode	Serves as the default hash function. (Inherited from Object.)
	GetOrigin	Get the geographical origin of the map projection
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	HasDatum	Returns true if the projectionString projection has a datum definition. If a projection does not have an underlying datum, reprojections including datum shifts cannot be performed.
	IsGeographical	Returns true if the projectionString projection is a geographical projection, i.e. based on spherical (lon, lat) coordinates
	IsGeoreferenced	Returns true if the projectionString projection is georeferenced, meaning that it is based on, or can convert to, geographical coordinates (longitude, latitude).
	IsLocal	Returns true if the projectionString defines a local coordinate system that is not georeferenced. The projection string for a local coordinate system is the string: "NON-UTM"
	IsLongLat	Returns true if the projectionString projection is "LONG/LAT" "LONG/LAT" is a geographical coordinate system without an underlying datum (ellipsoid) definition.
	IsValid	Returns true if the projectionString is a valid projection string
	Longitude2UtmZone	Get the projection string for the UTM zone best matching the longitude coordinate
	Proj2Geo	Convert coordinates from projection coordinates to geographical coordinates
	Proj2GeoRotation	Convert a rotation from map projection north into a rotation from true north. It adds the convergence value to the projection north rotation value The convertion depends on the geographical location.
	ProjectionOrigin(String, Double, Double)	Returns the geographical origin of the projection defined by the projstring If the projection string is not a valid WKT string, an exception is thrown.
	ProjectionOrigin(String, Double, Double, Boolean)	Returns the geographical origin of the projection defined by the projstring If the projection string is not a valid WKT string, an exception is thrown.
	ProjectionShortName	Get the short name out of a WKT projetion string. The short name is not unique amongst all WKT projections If the projString is not a WKT projection string, the projString itself is returned as the short name.
	ToString	Returns a string that represents the current object. (Inherited from Object.)
	Xyz2Geo	Convert coordinates from Euclidean 3D coordinates to geographical coordinates and height. The 3D coordinate system origin is at the earth center (ellipsoid center)

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Examples

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// WKT projection string
string projStr = @"PROJCS[""NZGD_2000_New_Zealand_Transverse_Mercator"",GEOGCS[""GCS_NZGD_2000"",DATUM[""D_NZGD_2000"",SPHEROID[""GRS_1980"",6378137.0,298.257222101]],PRIMEM[""Greenwich"",0.0],UNIT[""Degree"",0.0174532925199433]],PROJECTION[""Transverse_Mercator""],PARAMETER[""False_Easting"",1600000.0],PARAMETER[""False_Northing"",10000000.0],PARAMETER[""Central_Meridian"",173.0],PARAMETER[""Scale_Factor"",0.9996],PARAMETER[""Latitude_Of_Origin"",0.0],UNIT[""Meter"",1.0]]";
MapProjection mapProj = new MapProjection(projStr);

// Convert from projection to geographical coordinates.
double lon, lat;
mapProj.Proj2Geo(1752001, 5947201, out lon, out lat);

Reference

DHI.Projections Namespace