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

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

    Posted 11-23-2004 17:48
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    Subject: 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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