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Re: Chris Little's comments on the BP - Issues 128 and 204

From: Ed Parsons <eparsons@google.com>
Date: Fri, 19 Feb 2016 08:21:02 +0000
Message-ID: <CAHrFjcnMGowXh=qH5bc3HShbEMxy1GeOvSysm4eOFZ=FKHcOFg@mail.gmail.com>
To: Raphaël Troncy <raphael.troncy@eurecom.fr>, George Percivall <gpercivall@opengeospatial.org>
Cc: Jon Blower <j.d.blower@reading.ac.uk>, Frans Knibbe <frans.knibbe@geodan.nl>, SDW WG <public-sdw-wg@w3.org>, Chris Little <chris.little@metoffice.gov.uk>, Jeremy Tandy <jeremy.tandy@gmail.com>
HI Raphaël,

Thanks for your comments, you are of course correct that much authoritative
data held in various SDI' are published in local CRS with various levels of
visibility on the web. However they now represent a very small proportion
of the spatial data now on the web, I wonder how many minutes of geocoded
instagram pictures is equivalent to the French Open Data Portal.

CRS and the issues with particular systems is well understood by the
professionals who build such systems, there is less understanding in the
broader web community which I would argue is the main audience for our work.


On Thu, 18 Feb 2016 at 18:22 Raphaël Troncy <raphael.troncy@eurecom.fr>

> Dear Ed, all,
> > I do accept there are exceptions... what is your estimate of the % of
> > spatial data on the web that is not CRS84 ?
> This is a tricky question to answer in general, but I second the opinion
> that states that there is a LOT of spatial data on the web which is not
> CRS84, and in particular, authoritative data.
> Let's take an example, the official French Open Data Portal
> https://www.data.gouv.fr/fr/datasets/ ... there are thousands of
> datasets, coming from both the public administration and the private
> sectors. Most of the data is geo-localized ... and rarely the CRS used
> is WGS84. For example, pick the dataset that describes ALL
> (primary/secondary) schools in France [1] and try to plot the schools on
> a map by interpreting that the coordinates are in WGS84 ... you will
> find many schools in the ocean. In this dataset, you have to interpret
> the geo coordinates of the schools in France Metropolitan in RGF93, the
> ones in Guadeloupe/Martinique in CRS84, the ones in Guyanne in RGFG95,
> the ones in Réunion in RGR92, etc.
> This is not an exception ... this is the rule! All official data from
> the French public administration will come in RGF93 (Lambert93). Many
> European countries have similar rules.
> This does definitively not cover 1% of the spatial data on the web
>    Raphaël
> [1]
> https://www.data.gouv.fr/fr/datasets/adresse-et-geolocalisation-des-etablissements-denseignement-du-premier-et-second-degres/
> --
> 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/

*Ed Parsons*
Geospatial Technologist, Google

Google Voice +44 (0)20 7881 4501
www.edparsons.com @edparsons
Received on Friday, 19 February 2016 08:21:44 UTC

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