Type of the datum expressed as an enumerated value.
The enumeration is split into ranges which indicate the datum's type. The value should be one of the predefined values, or within the range for local types. This will allow OGC to coordinate the addition of new interoperable codes.
| Member Name | Description |
|---|---|
| IHD_Classic | These datums, such as ED50, NAD27 and NAD83, have been designed to support horizontal positions on the ellipsoid as opposed to positions in 3-D space. These datums were designed mainly to support a horizontal component of a position in a domain of limited extent, such as a country, a region or a continent. |
| IHD_Geocentric | A geocentric datum is a "satellite age" modern geodetic datum mainly of global extent, such as WGS84 (used in GPS), PZ90 (used in GLONASS) and ITRF. These datums were designed to support both a horizontal component of position and a vertical component of position (through ellipsoidal heights). The regional realizations of ITRF, such as ETRF, are also included in this category. |
| IHD_Max | Highest possible value for horizontal datum types. |
| IHD_Min | Lowest possible value for horizontal datum types. |
| IHD_Other | Unspecified horizontal datum type. Horizontal datums with this type should never supply a conversion to WGS84 using Bursa Wolf parameters. |
| ILD_Max | Highest possible value for local datum types. |
| ILD_Min | Lowest possible value for local datum types. |
| IVD_AltitudeBarometric | The vertical datum of altitudes or heights in the atmosphere. These are approximations of orthometric heights obtained with the help of a barometer or a barometric altimeter. These values are usually expressed in one of the following units: meters, feet, millibars (used to measure pressure levels), or theta value (units used to measure geopotential height). |
| IVD_Depth | This attribute is used to support the set of datums generated for hydrographic engineering projects where depth measurements below sea level are needed. It is often called a hydrographic or a marine datum. Depths are measured in the direction perpendicular (approximately) to the actual equipotential surfaces of the earth's gravity field, using such procedures as echo-sounding. |
| IVD_Ellipsoidal | A vertical datum for ellipsoidal heights that are measured along the normal to the ellipsoid used in the definition of horizontal datum. |
| IVD_GeoidModelDerived | A vertical datum of geoid model derived heights, also called GPS-derived heights. These heights are approximations of orthometric heights (H), constructed from the ellipsoidal heights (h) by the use of the given geoid undulation model (N) through the equation: H=h-N. |
| IVD_Max | Highest possible value for vertical datum types. |
| IVD_Min | Lowest possible value for vertical datum types. |
| IVD_Normal | A normal height system. |
| IVD_Orthometric | A vertical datum for orthometric heights that are measured along the plumb line. |
| IVD_Other | Unspecified vertical datum type. |
Namespace: Geotools.CoordinateReferenceSystems Namespace
Assembly: Geotools.dll
Geotools.CoordinateReferenceSystems Namespace