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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 
Portal: 
https://www.data.gouv.fr/fr/datasets/adresse-et-geolocalisation-des-etablissements-denseignement-du-premier-et-second-degres/. 
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

-- 
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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