CrsCoodinateReferenceSystemType Enumeration |
Namespace: FDF.Common.CoordinateSystemsAssembly: FDF.Common (in FDF.Common.dll) Version: 3.0.0.0
Syntax public enum CrsCoodinateReferenceSystemType
Public Enumeration CrsCoodinateReferenceSystemType
public enum class CrsCoodinateReferenceSystemType
type CrsCoodinateReferenceSystemType
Members
| Member name | Value | Description |
---|
| Compound | 0 |
In historic geodetic practice, horizontal and vertical positions were determined independently.
It is established practice to combine the horizontal coordinates of a point with a height or depth
from a different coordinate reference system. This has resulted in coordinate reference systems that
are horizontal (2D) and vertical (1D) in nature, as opposed to truly 3-dimensional. The coordinate
reference system to which these 2D+1D coordinates are referenced combines the separate horizontal and
vertical coordinate reference systems of the horizontal and vertical coordinates. Such a system is
called a compound coordinate reference system (CCRS). It consists of a non-repeating sequence of two
or more single coordinate reference systems. The coordinate order within a coordinate tuple for a
compound CRS is the sequence of the component single CRSs and then the sequence of coordinates for the
coordinate tuples for each of those component single CRSs.
|
| Engineering | 1 |
A coordinate reference system that is used only in a contextually local sense. This sub-type
is used to model two broad categories of local coordinate reference systems: a) earth-fixed systems,
applied to engineering activities on or near the surface of the earth; b) coordinates on moving
platforms such as road vehicles, vessels or aircraft. Earth-fixed Engineering CRSs are commonly
based on a simple flat-earth approximation of the earth's surface, and the effect of earth curvature
on feature geometry is ignored: calculations on coordinates use simple plane arithmetic without any
corrections for earth curvature. The application of such Engineering CRSs to relatively small areas
and "contextually local" is in this case equivalent to "spatially local".
|
| Geocentric | 2 |
A coordinate reference system that deals with the earth's curvature by taking the 3D spatial view,
which obviates the need to model the earth's curvature. The origin of a geocentric CRS is at the
approximate centre of mass of the earth.
|
| Geographic2D | 3 |
A coordinate reference system based on an ellipsoidal (including spherical) model of the earth.
This provides an accurate representation of the geometry of geographic features for a large portion
of the earth's surface. Used when positions of features are described on the surface of the
ellipsoid through latitude and longitude coordinates
|
| Geographic3D | 4 |
A coordinate reference system based on an ellipsoidal (including spherical) model of the earth.
This provides an accurate representation of the geometry of geographic features for a large portion
of the earth's surface. Used when positions are described on, above or below the ellipsoid and
includes height above the ellipsoid. These ellipsoidal heights (h) cannot exist independently,
but only as an inseparable part of a 3D coordinate tuple defined in a geographic 3D coordinate
reference system. Thus ellipsoidal heights cannot be referenced to a vertical coordinate reference system.
|
| Projected | 5 |
A coordinate reference system that is based on an approximation of the shape of the earth's surface
by a plane. The distortion that is inherent to the approximation is carefully controlled and known.
Distortion correction is commonly applied to calculated bearings and distances to produce values that
are a close match to actual field values. A Projected CRS is derived from a Geographic 2D CRS.
One geographic CRS may serve as the base for many projected CRSs.
|
| Vertical | 6 |
A coordinate reference system which makes use of the direction of gravity to define the concepts
of height (H) or depth. The relationship with gravity may be complex.
|
See Also