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Re: UCR ISSUE-70: add a requirement for avoiding coordinate transformations? [SEC=UNCLASSIFIED]

From: Raphaël Troncy <raphael.troncy@eurecom.fr>
Date: Mon, 5 Sep 2016 15:41:47 +0200
To: Frans Knibbe <frans.knibbe@geodan.nl>, Rob Atkinson <rob@metalinkage.com.au>
Cc: Bruce Bannerman <B.Bannerman@bom.gov.au>, SDW WG Public List <public-sdw-wg@w3.org>
Message-ID: <5e8b6af4-69fa-d6fd-4101-1dab971db0b0@eurecom.fr>
Dear Frans,

> But if there are cases where publishing data with multiple CRSs is
> a hard rule that must be complied with it would be good to have them in
> the UCR document. And that would probably mean we have to formulate
> another requirement in the UCR doc, e.g. 'it must be possible to publish
> geometric data with multiple CRSs'.

I have a good example, that I used already many years ago during my 
presentation at the workshop that precedes the creation of this joint 
OGC-W3C working group.

Have a look at this dataset published on the French Government Open Data 
This dataset is provided in the CSV format. It lists all primary and 
secondary schools in France, with their geo-coordinates, name, address, 
state, etc. While there is a single file, the various values of the 
columns 'coordonnee_x' and 'coordonnee_y' MUST be interpreted 
differently. The explanatory note adds the following information:

"The coordinates X and Y are provided by IGN according to various CRS / 
projections being used:"
  - France métropolitaine: 	RGF93 - Lambert 93
  - Guadeloupe: 	         	WGS84 - UTM Nord fuseau 20
  - Martinique :	                WGS84 - UTM Nord fuseau 20
  - Guyane : 	                RGFG95 - UTM Nord fuseau 22
  - Réunion : 	                RGR92 - UTM Sud fuseau 40

This means that depending on which places you are on earth, you have to 
interpret geo-coordinates differently, otherwise, you will plot schools 
in the middle of the sea ...
Best regards.


Raphaël Troncy
EURECOM, Campus SophiaTech
Data Science Department
450 route des Chappes, 06410 Biot, France.
e-mail: raphael.troncy@eurecom.fr & raphael.troncy@gmail.com
Tel: +33 (0)4 - 9300 8242
Fax: +33 (0)4 - 9000 8200
Web: http://www.eurecom.fr/~troncy/
Received on Monday, 5 September 2016 13:42:44 UTC

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