RE: ISO Definitions for corodinate, coordinate system, etc.

All -

The following are terms and definitions from ISO 19111 - Spatial 
Referencing by Coordinates and the OGC Abstract Specification, Topic 2: Spatial 
Referencing by Coordinates. Use as necessary. The normative reference would 
be:

ISO 19111, Geographic 
Information – Spatial Referencing by Coordinates

Cheers

Carl

Terms and definitions

For the purposes of this document, the following terms and 
definitions apply. Some definitions deviate from ISO/DIS 19111, where more 
universally valid definitions are provided.

4.1

Cartesian coordinate system

coordinate system which gives the position of points relative to 
N mutually-perpendicular straight axes

NOTE In the context of geospatial coordinates the maximum value of 
N is three.

4.2

compound coordinate reference system

coordinate system describing the position of points through two or 
more independent coordinate reference systems

EXAMPLE One coordinate reference system can be a two-dimensional 
horizontal coordinate system, and the other coordinate reference system can be a 
vertical gravity-related height system.

4.3

concatenated transformation

sequential application of multiple 
transformations

4.4

coordinate

one of a sequence of N 
numbers designating the position of a point 
in N-dimensional space

NOTE In a coordinate reference system, the coordinate numbers must 
be qualified by units.

OGC 03-073r1

© OGC 2003 – All rights reserved 3

4.5

coordinate conversion

change of coordinates, based on a one-to-one relationship, from 
one coordinate reference

system to another based on the same datum

EXAMPLE Between geodetic and Cartesian coordinate systems or 
between geodetic coordinates and projected

coordinates, or change of units such as from radians to degrees or 
feet to metres.

NOTE A conversion uses parameters which have specified values, not 
empirically determined values.

4.6

coordinate reference system

coordinate system which is related to the real world by a 
datum

NOTE For geodetic and vertical datums, it will be related to the 
Earth.

4.7

coordinate system

set of (mathematical) rules for specifying how coordinates are to 
be assigned to points

NOTE 1 One coordinate system may be used in many coordinate 
reference systems.

NOTE 2 The geometric properties of a coordinate space determine 
how distances and angles between

points are calculated from the coordinates. For example, in an 
ellipsoidal (2D) space distances are defined

as curves on the surface of the ellipsoid, whereas in a Euclidean 
plane as used for projected CRS distance is

the length of a straight line between two points. The mathematical 
rules that determine distances and angles

are calculated from coordinates and vice versa are comprised in 
the concept of coordinate system.

Carl Reed, PhD
CTO and Executive Director Specification 
Program
OGC

 

The OGC: Helping the World to Communicate Geographically

 

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