Cartography Class

Cartography Class

A cartography object handles a map projection and a local grid that can be translated and rotated relative to the projected coordinate system.

There are 3 levels of coordinates: Geographical coordinates (longitude, latitude) in degrees, projection coordinates (easting, northing), and local/model/user grid coordinates (x,y).

The ProjectionString defines the mapping from geographical coordinates to projection coordinates.

The LatOrigin, LonOrigin and Orientation defines the origin and the orientation of the local grid coordinates. It defines how the local grid coordinate system is translated and rotated. This kind of local grid coordinate system is used for e.g. a 2D grid in a dfs2 file.

See Orientation for the definition of the orientation. The local grid are rotated around its origin.

If LonOrigin is zero, and LatOrigin and ProjectionOrigin(String, Double, Double) matches the origin of the projection coordinate system (from MapProjection), then projection coordinates equals local grid coordinates. Example: UTM-31 has projection origin at (lon,lat) = (3,0).

Inheritance Hierarchy

SystemObject
DHI.ProjectionsCartography

Namespace: DHI.Projections
Assembly: DHI.Projections (in DHI.Projections.dll) Version: 16.0.0.0 (11.1.1.1111)

Syntax

C++

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public class Cartography

Public Class Cartography

public ref class Cartography

type Cartography =  class end

The Cartography type exposes the following members.

Constructors

	Name	Description
	Cartography(String, Boolean)	Create and initialize a Cartography object using the specified projection string.
	Cartography(String, Double, Double, Boolean)	Create and initialize a cartography object using the specified projection string, setting the origin of the user defined local grid coordinates to the lonOrigin, latOrigin
	Cartography(String, Double, Double, Double, Boolean)	Create and initialize a cartography object using the specified projection string, setting the origin of the user defined local grid coordinates to the lonOrigin, latOrigin, rotated orientation.

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Properties

	Name	Description
	EastOrigin	Get the origin easting coordinate of the local grid coordinate system. For geographical map projections ((lon,lat) coordinates), this has no meaning (has the same value as the LonOrigin)
	LatOrigin	Get the origin latitude coordinate of the local grid coordinate system.
	LonOrigin	Get the origin longitude coordinate of the local grid coordinate system.
	NorthOrigin	Get the origin northing coordinate of the local grid coordinate system. For geographical map projections ((lon,lat) coordinates), this has no meaning (has the same value as the LatOrigin)
	Orientation	Get the orientation of the local grid coordinate system in the geographical coordinate system. The orientation is the angle in degrees between true north and the coordinate system y-axis in degrees, measured positive clockwise from true north.
	OrientationProj	Get the orientation of the local grid coordinate system in the projected coordinate system. The orientation is the angle in degrees between projection north and the coordinate system y-axis in degrees, measured positive clockwise from projection north. For geographical map projections ((lon,lat) coordinates), this has no meaning (has the same value as the Orientation)
	Projection	Get the map projection that this cartography object uses.
	ProjectionName	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.
	ProjectionNorth	Obsolete. Returns the angle between projection north and a line parallel to the local grid. This is NOT the same as the Orientation, the orientation is towards true north, this is towards projection north.
	ProjectionString	Returns the WKT projection string, or one of the projection abbreviation strings.

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Methods

	Name	Description
	CreateGeoOrigin	Create and initialize a cartography object using the specified projection string, setting the origin of the user defined local grid coordinates to the geographic coordinates lonOrigin, latOrigin, rotated orientation.
	CreateProjOrigin	Create and initialize a cartography object using the specified projection string, setting the origin of the user defined local grid coordinates to the projected coordinates east, north, rotated orientationProj towards projection north.
	Equals	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Geo2Proj	Convert coordinates from geographical coordinates to projection coordinates
	Geo2Xy	Convert coordinates from geographical coordinates to local grid x-y coordinates
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetTrueNorth	Returns the angle between true north and a line parallel to the local grid y axis passing through (x,y). The angle is in degrees, measured positive clockwise from true north.
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	Proj2Geo	Convert coordinates from projection coordinates to geographical coordinates
	Proj2Xy	Convert coordinates from projetion coordinates to local grid x-y coordinates
	ToString	Returns a string that represents the current object. (Inherited from Object.)
	Xy2Geo	Convert coordinates from local grid x-y coordinates to geographical coordinates
	Xy2Proj	Convert coordinates from local grid x-y coordinates to projection coordinates

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Examples

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// The abbreviation for the long WKT projection string
utm33String = "UTM-33"; 

// Create a Cartography object with a local grid origin at lon-lat (17,55)
// rotated -45 degrees from true north.
Cartography cart = new Cartography(utm33String, 17, 55, -45);
double east, north, x, y;

// Convert from geographical to map projection coordinates
cart.Geo2Proj(17, 55, out east, out north);

// Convert from geographical to local grid coordinates
cart.Geo2Xy(17, 55, out x, out y);

Reference

DHI.Projections Namespace