NewZealandMapGridProjection Class
A map projection for New Zealand.
NuGet/Assembly: Carmenta.Engine.5.16.2.nupkg (in the CECore assembly)
Syntax
public class NewZealandMapGridProjection : ProjectionRemarks
The New Zealand Map Grid, or NZMG, is a conformal projection adopted in 1973, carefully designed to minimize the scale variation within the country. The projection is used with the old datum of New Zealand, NZGD49. It is a beautiful piece of mathematics, but when New Zealand defined its new and WGS84-compatible datum, NZGD2000, it was decided to use a TransverseMercatorProjection instead, for interoperability.
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The map above shows lines of constant local scale factor for NZMG. The displayed numbers show how much the local scale factor differs from 1, expressed in ppm (parts per million). Such lines for a map projection do not usually follow the country shape so well, but the mathematical formulas for this projection are tailor-made for New Zealand. The scale variation is only +/- 250 ppm on the main islands, which is excellent.
Unfortunately, the minimal distortion in the area of interest comes at a price: huge distortions elsewhere.
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The image above shows how the projection bends the graticule into whirlpools at four places. In fact, geographic features even farther away can be projected into the area of interest. So, the projection must not be used too far from New Zealand. To avoid trouble, Carmenta has limited the extent of the projection. (The image above was created before the limitation was implemented.) However, to enjoy full safety from the limited extent, you must insert a RectangleClipOperator to the left of a DataSet, whenever the view uses the New Zealand projection and the dataset does not.
Inheritance Hierarchy
System.Object (not available in C#)
EngineObject
ResourceObject
Projection
NewZealandMapGridProjection
Platforms
Windows, Linux, Android
NewZealandMapGridProjection Members
The NewZealandMapGridProjection type has the following members.
Constructors
| Name | Description |
|---|---|
| NewZealandMapGridProjection | Creates a new instance of the New Zealand Map Grid. |
Properties
| Name | Description |
|---|---|
| Authority | Gets the name of an authority, which is often "epsg". Inherited from Projection |
| AuthorityCode | Gets the unique code for the projection instance, according to the Authority, for example "19883". Inherited from Projection |
| IsDisposed | Gets a value that tells whether the current NewZealandMapGridProjection has been disposed. Inherited from EngineObject |
 LongLat | Gets a pre-defined LongLatProjection instance. Inherited from Projection |
| Name | Gets or sets the name of the NewZealandMapGridProjection. Inherited from ResourceObject |
| NativeHandle | Gets the native Carmenta Engine kernel object the current NewZealandMapGridProjection represents. Inherited from EngineObject |
| IUserProperties.UserProperties | Gets the AttributeSet that contains the user properties. Inherited from IUserProperties |
Methods
| Name | Description |
|---|---|
| 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 |
| Utm | Returns one of the 120 predefined instances of Universal Transverse Mercator. Inherited from Projection |