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

• From: "Carl Reed OGC" <creed@opengeospatial.org>
• To: "emergency TC lists Oasis" <emergency@lists.oasis-open.org>
• Date: Tue, 23 Nov 2004 10:47:47 -0700

 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, PhDCTO and Executive Director Specification ProgramOGC   The OGC: Helping the World to Communicate Geographically   ---------------------       This communication, including attachments, is for the exclusive use of addressee and may contain proprietary, confidential or privileged information. If you are not the intended recipient, any use, copying, disclosure, dissemination or distribution is strictly prohibited. If you are not the intended recipient, please notify the sender  immediately by return email and delete this communication and destroy all copies.

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