So on this issue I currently only speak on the "bulk updating" issue and I
would like to note that I do not speak for the discovery team who have the
most focus on both geodata and Wikidata. However I do have a decent passing
knowledge about this:

This is a pretty complex issue compounded that geographical data has
historically been pretty unloved over the years not just by mediawiki
(wikidata support as well) because it is an extremely complex thing by it's
very nature.. Unfortunately this leads to click bait by people like the
National Geographic "Australia Is Drifting So Fast GPS Can't Keep Up".

*1)* *GPS does not equal GDA94 *
Firstly GPS itself is not changing at this point (It does get periodic
adjustments but this is not one of them). In this instance it is that
Australia is moving from one conventional datum (GDA94
https://en.wikipedia.org/wiki/Geocentric_Datum_of_Australia_1994) to a new
conventional datum with the aim for it to be used in perpetuity - GDA2020 (
http://www.icsm.gov.au/geodesy/modern.html - No wikipedia article, I should
probably write it) and also at the same time creating a new reference
system ATRS (Australian Terrestrial Reference System -
https://en.wikipedia.org/wiki/International_Terrestrial_Reference_System).

GDA94 uses the exact same number system as WGS84 (
https://en.wikipedia.org/wiki/World_Geodetic_System) which adds to the
confusion.

Which leads me to point 2 -

*2)* *Wikimedia Coordinates are assumed to be WGS84 *
Wikimedia has typically used WGS84 coordinates because of their
universality especially on the web (
https://en.wikipedia.org/wiki/Web_Mercator). Generally we don't support
providing local cartographic grids within articles (at least not I can't
seems to find such support)  Unfortunately what this means is that we have
to assume that grid references we currently use and store are WGS84
coordinates. However this comes with problems because sometimes WGS84 is
updated as geodetic and dynamic plate models improve. There is additional
vital metadata needed for this.

Unfortunately we currently do not store that information within Wikipedia
articles or  which leads to point 3 -

*3) Without the correct metadata, it's impossible to the job well *
Because currently there is no clear indication within Wikipedia articles
and as far as I can tell within Wikidata as to both what *datum* and what
*version* any particular coordinate relates to, there is no guarantee that
any particular coordinate would be any more correct than it was before.

Going forward we should really should greatly increase the amount of
support for geographic metadata within Wikidata. As a result coordinate
updates, even fairly minor ones, create inordinate amounts of unnecessary
work for volunteers. Good metadata with allows us (either WMF or
volunteers) to use translation models that should allow us to be able to
maintain such data with minimal volunteer overhead. Without it, it's a
headache.

I hope I explained that well... Make sense?

-- 

Seddon
*The Silent Cartographer*


On Mon, Oct 3, 2016 at 3:33 PM, Gnangarra <gnanga...@gmail.com> wrote:

> G'day
>
> This story raises an interesting question
> http://www.sciencealert.com/turns-out-australia-isn-t-where-
> you-think-it-is
>
> In short the GPS location of Australia is about to be adjusted 1.5m or
> about 5feet I know its not as significant as the change of 1994 when it was
> adjusted 200m.  This shift that will alter all the GPS data held in
> Wikidata and alter the positioning of media files which have been
>  geolocated.
>
> The question is are there any plans to bulk update all of this information,
> or will it rely on individual changes to be made to each piece of data.  As
> a secondary question do we even change the location of media files as that
> data is accurate to when the media was created.
>
> --
> G
> ​nangarra​
>
> President Wikimedia Australia
> WMAU: http://www.wikimedia.org.au/wiki/User:Gnangarra
> Photo Gallery: http://gnangarra.redbubble.com
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-- 
Seddon

*Advancement Associate (Community Engagement)*
*Wikimedia Foundation*
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