Spatial reference system

A coordinate reference system or coordinate reference system ( KBS ), Eng. coordinate reference system, abbreviated internationally with CRS, is a coordinate system that is referenced by linking with a date in the real world. For a description of the earth, the Geodetic Vertical date or date is used.

The term was used in the ISO 19111 Geographic information - Spatial referencing by introduced and defined coordinates.

Types of coordinate reference systems

The following types of coordinate reference systems are distinguished mainly:

Geographical CRS

The geographic CRS, a ellipsoid model of the Earth, to describe the position of an object with two-dimensional coordinates (longitude and latitude) on its surface. The location of the artificial ellipsoid with respect to the real world is described by a geodetic datum

If an additional amount indicated, which is based on the ellipsoid, this is referred to as a 3D Geographic CRS.

Geocentric CRS

The geocentric CRS is the center of gravity of the earth as the center, and three-dimensional coordinates used to describe the position of an object.

Geodetic CRS

Geographic and geocentric CRS are also referred to as geodetic CRS.

Other CRS

• Projects: is a geographic CRS, in which the coordinates were projected by a map projection into the plane.
• Local: a CRS that is used only in a local context; relative about for construction activities or for determining coordinates for moving objects ( such as ships or aircraft).
• Combined: CRS for which the position and the height is determined in different reference systems.

Demarcation Spatial Reference System

The standard ISO 19112 Spatial referencing by geographic identifiers distinguishes the concepts of coordinate reference system and Spatial Reference System ( engl: spatial reference system - SRS). Unlike coordinate reference systems ( CRS), which coordinates the manufacture referencing, use spatial reference systems (SRS ) to geographic or semantic labels. This can be, for example postal addresses or very general statements such as " On the Alexanderplatz in Berlin " and " East of the Zugspitze ".

EPSG code

→ Main article EPSG codes

EPSG codes are a widely used means to uniquely specify the spatial reference of spatial data. The 4 - to 5-digit code numbers each include a complete description of a coordinate reference system. There are several hundred of these reference systems, and each consists of a list 10 to 20 parameters. They are described in the list of EPSG codes. Due to the short code number these complex relationships can be exchanged in a simple form internationally.