
NSW and Victoria just jumped 1.8 metres north - ColinWright
https://www.smh.com.au/national/nsw-and-victoria-just-jumped-1-8-metres-north-20200102-p53ocx.html
======
wycy
Somewhat clickbaity headline. The change is being made to fix a 1.8 metre
inaccuracy that has crept into our GPS coordinates, caused by Australia slowly
drifting north.

------
shakna
> It will take some time for companies like Google to pick up and implement
> the new data. But when they do, you will enjoy slightly more accurate
> satellite navigation.

I wouldn't hold my breath. Google's adoption of updated information for
anything other than the capital cities is extremely slow. On the order of the
data has been in OSM for five years slow.

Google has photographs of my house from above, and from the road, and doesn't
list the road as existing.

They're probably inclined to add this GPS shift data for the capital cities -
but the mapping data will probably be inconsistently updated.

Especially as the state and territories provide the data in an incredibly wide
range of formats.

VIC, NSW, SA provide shapefiles, which is great, as it is becoming one of the
more popular standard. (They also export for a range of other data types).

The NT provides a strange mix of shapefiles and custom xlsx sheets. Unless
you're looking at Darwin or the heart of the Kimberly's, you'll be looking at
human-written Excel sheets for a lot of this.

QLD, the ACT and WA seem to use OpenGIS/ArcGIS XML files.

Tasmania doesn't maintain their own data, but relies on ANZLIC to do it for
them, and seem to be in the middle of an argument over who will do the
maintenance moving forward. (The last update to any of their public data
appears to be in 2016.) This was shapefile/export like VIC, NSW and SA, but it
becomes somewhat useless if it never gets updated.

If you're an islander, you sort of have to hope that the state/territory
includes you in their dataset. They don't always. And they're not consistent
about when they include you. Regressions are common. Councils tend to maintain
their own data, but rarely allow anyone access, paid or not. If you hand them
a FOIA request to see the data, then... Well, I got handed a series of printed
XML documents, after six months of them threatening to take me to court for
requesting it. Multiple island "councils" (often different names, but similar
functions) did this.

~~~
andrewstuart2
You should be able to easily submit corrections to the Google maps data,
especially if the overhead satellite data already matches. I was able to get
my house and street corrected with just a couple requests.

~~~
simsla
Tried that as well. (extensively documented to show they swapped street
names.) Ticket was closed after half a year without comment.

They have a system but seem to be missing the processes.

~~~
xbmcuser
I tried getting them to correct the location for the apartment I used to live
in for months but it kept bieng rejected. I recently got a message 3 years
after I had moved that my edit was accepeted.

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woliveirajr
This animation [0], from the Australia Government, made my day on why it's
important to have correct coordinates for your country.

[https://www.icsm.gov.au/sites/default/files/inline-
images/Fi...](https://www.icsm.gov.au/sites/default/files/inline-
images/Field_Gif.gif) [0]

------
alleycat5000
If you want some details from a more rigorous point of view, check out

[https://www.icsm.gov.au/gda2020/what-changing-and-
why](https://www.icsm.gov.au/gda2020/what-changing-and-why)

Similar efforts are going on elsewhere, e.g.

[https://www.ngs.noaa.gov/datums/newdatums/TrackOurProgress.s...](https://www.ngs.noaa.gov/datums/newdatums/TrackOurProgress.shtml)

------
ash
> To fix this, all Australian states and territories have agreed to update
> their coordinates by June. However, they are all doing it at their own
> speeds.

> Official government road maps and property boundaries will now line up
> perfectly with GPS location data.

> It will take some time for companies like Google to pick up and implement
> the new data. But when they do, you will enjoy slightly more accurate
> satellite navigation.

I don't get it. Does Google have to wait for government? Why couldn't Google
incrementally add 1.8 meter to its maps on its own schedule, years ago?

~~~
reaperducer
_Does Google have to wait for government?_

Thought we like to think of Google as a big data company, for many of its
projects it's more an aggregator of other people's data. Yes, it does create
original data. But a lot of its data is from outside sources. Very often data
that you paid for with your tax dollars, and then get to pay for again with
your privacy.

------
dwyerm
This isn't a novel thing, as far as I can tell. A decade ago when I was
working on routing of over-the-road trucking, our maps provider moved the
entire United States a couple meters and it broke all our road restrictions.

The problem for us -- and likely for those in Australia now -- is that
converting physical address descriptions and lat/long becomes a little more
fraught. We described road restrictions as being "on the road that is found
between X1,Y1 and X2,Y2." A separate layer would snap those X,Y coordinates to
the road network and find the road between them. Before the move, that meant
converting to "Highway 6 Southbound from milemarker 16 to milemarker 28"

But when you moved the world, X1,Y1 no longer landed on Highway 6, and instead
snapped over to the frontage road. Your restriction now read as "Highway 6
Southbound, down to exit 21, around the corner to the frontage road, then down
the frontage road". And your restriction that used to say "stay off this one
section of road" now says "stay off the highway, the frontage road, and don't
use this exit."

~~~
beerandt
While the problem isn't novel, that's probably not what happened with what
you're describing, for a number of reasons.

Most local datums are anchored to the local geology. So in the US, if you're
using nad27 or nad83, the reference system is "moving" along with the
continent (nad83 = North American Datum 1983), based on some weighted
benchmark vectors and a lot of math. It's one reason why different datums with
defined epochs exist. Some are static, but some are actually dynamic with time
(eg ITRF).

But most people don't grok any of that and just stick with defaults, or guess-
and-check during map setup and go with whatever looks "close enough".

In your case, chances are the map provider switched datums with the update,
from nad27 to nad83, and your software wasn't told about the change. Or it
was, but your road restriction data was drawn in the old projection, and not
converted / transformed to the new one.

Or, you could have had data that initially was mislabeled, recorded with GPS
(wgs84) and entered using one of the many datums that's similar, but not the
same. Or maybe collected using one of the many state plane coordinate systems
(which people tend to like because it's more or less Cartesian- east,north)
which are themselves built in top of one of the datums. You can pick the right
coordinate zone, but wrong underlying datum.

If any data provider or aggregator or if your company GIS guru ever selected
the wrong projection (choices often are dozens of coded options that look
nearly identical), or left it blank (undefined) because they weren't sure...

A instant "shift" would happen as soon as you "corrected" the error, (or
upgraded software, or any other number of situations).

This is where a good GIS guru earns their keep, because conversions between
projections and datums are just math, and data can often be corrected in
seconds by running it through a manual "inverse" conversion, assuming one can
recognize what happened.

Back to Australia: if people used GPS coordinates (wgs84) and didn't convert
to a Australian centric datum (which is the default option for most
collectors), the data would "stay still" while the continent moves. Which is
one of many reasons why selecting an appropriate datum/ projection is so
important.

For the US: While there is some intra-datum movement between nad27 and nad83,
most of the differences are do to improvements in the quality and accuracy of
surveys over half a century. So the differences between the two datums tend to
grow as you get further from the beginning points of the surveys.

Which means some areas, like a lot of the East coast, have minimal
differences, and areas out West have larger deltas, but it varies.

A couple of meters would be better explained by a bad datum transformation
than by drift, which is likely an order of magnitude smaller at even the worst
locations for the US.

------
antxxxx
Does anybody know how what3words is dealing with this? Do locations suddenly
have a new 3 word location, or have the words stayed the same and the location
they refer to (in GPS co-ordinates) changed?

~~~
shakna
I believe what3words encodes latitude and longitude, so the location they
refer to will have changed.

However, what3words is only accurate to 3m, so this change may not have
affected their system at all.

~~~
ferzul
well, plenty of places could have moved out of their box. many urban
properties are quite narrow; i lived on one not even 2.5 metres wide, so every
3m box would be in use (and potentially then some) on that street. (i didn't
have an address living there either, but w3w wasn't going to help that problem
much. easier to give a recognisable landmark.)

------
gorgoiler
Very exciting to have a tangible feeling for plate tectonics like this, and
great reporting. As the article says, in the course of a lifetime the
continental plate has drifted enough for GPS to mean your Uber shows up on the
wrong side of the street.

------
norswap
I'm surprised big GPS users like Google haven't already fixed this on their
apps as post-GPS corrective step. Another example of caring little and doing
the job so-so :/

~~~
beart
Sometimes it's better if everyone uses the same _wrong_ value vs one entity
using a different _correct_ value.

------
close04
Non clickbaity version: they did not “jump” anywhere, the coordinates for GPS
were just updated for the first time since 1994 to account for the constant
movement of 7cm per year. And it’s not just these 2 parts of Australia, it’s
all if it. NSW and Victoria just moved slightly more than the rest (1.8m vs.
1.5m or 1.7m for other parts).

~~~
bla3
Not quite: "To fix this, all Australian states and territories have agreed to
update their coordinates by June. However, they are all doing it at their own
speeds. On January 1, the Victorian and NSW governments updated the
coordinates of every road, property and geographical feature in their states,
essentially moving the south-eastern seaboard 1.8 metres north-east
overnight."

So all of Australia will move by June, but so far only NSW and Victoria have.

I don't see why it's a good idea to update coordinates of different parts of a
continent at different times. Likely a political decision, not a technical
one.

~~~
close04
The complaint was towards the clickbaity title which leads one to believe
there must have been a sudden tectonic event that caused the continent to
move.

“Florida man jumps back in time by one hour!” - leap hour reporting.

------
chris_wot
This mentioned Google hasn’t updated to this change, do we know when they
will?

~~~
saalweachter
The trickiness is going to be two-fold.

The trickiest part is going to be that some previous GPS coordinates will have
been "pinned" to the 1994 grid, and others will have been taken live over that
time span.

See, surveyors have always known that you can't _actually_ just write down the
GPS coordinates of a boundary or intersection or bridge, because of this exact
problem. So surveyors do the math (well, most likely their specialized
surveying GPS equipment does the math) and write down the coordinates relative
to the baseline for the continental plate in question.

If you have coordinates you know were LAT, LNG in the 1994 baseline, it's easy
to apply the transform and get the LAT', LNG' in the new 2020 baseline.

But what happens if your coordinates _weren 't_ provided by a surveyor
carefully surveying a location in the appropriate baseline? What if your
coordinates were measured by a jerk walking to a place last year with a GPS
and writing down whatever was displayed? _Those_ coordinates don't need to be
transformed, they were already basically correct for the 2020 baseline. If you
add the correction to those numbers you're introducing a new error. And to
make matters worse, people have been entering non-calibrated numbers into your
data set for _25 years_ \-- some numbers will have 5 years of drift, some 15
years. If you know _when_ an uncalibrated measurement was made, you can kind-
of interpolate the drift, but without that you're just SoL.

To make matters worse, a company like Google is using data from a wide variety
of sources, some they gathered themselves, some they get from others. With
your own data, you might at least know either whether it was calibrated to the
previous baseline or at least when it was collected, but someone else's
dataset might be _messy_ in unknownable ways.

Say you previously got the location of a park entrance from a government parks
department, in the 1994 coordinates. Now you go through your aggregated
dataset and apply the transformation to the coordinates and get the new number
in 2020 coordinates (which thankfully will match what a consumer GPS actually
says, now). Next month, when you update your data from the government parks
department, it gives you a _different_ coordinate for the park entrance, which
is neither the number you had previously for the entrance in 1994 coordinates
nor the number you computed in 2020 coordinates.

Now, do you assume that new number is in the new coordinate system, or might
it still have been measured in the old coordinate system, either having been
measured prior to the changeover or just on old equipment that was not
updated? Ideally your interchange format would include the time a GPS
measurement was taken as well as any baseline it was calibrated to, but do you
want to guess how often interchange formats are "ideal"?

So, long story short, it's going to be a long time before most of the old
coordinates are flushed from the system, and you'll probably occasionally see
a "wrong" coordinate that can be traced to this sort of thing every now and
again for the rest of your life.

~~~
Thorentis
I hadn't thought of this, thanks for explaining it so thoroughly.

Could you explain though, how you record LAT, LNG coords relative to a
continental plate baseline? I thought to solve this problem you simply
recorded the time that the measurement was taken, so that you can update the
coords based on known plate position data at a given time (e.g. if you know a
position was recorded somewhere in Aus in 2018, you just add 2cm x 7cm/yr =
14cm north east to the measurement to get the 2020 coords).

~~~
saalweachter
That's honestly getting to a point I only know vaguely about -- my real-world
experience is just from chatting with surveyors when I needed to get a couple
of parcels of land surveyed (once for a boundary survey, wherein I'm not sure
this came up, and once for a FEMA/flood zone survey, where matching the site
data to the FEMA data was much more important).

Part of the answer, in the US, (and the expensive equipment -- one of the
smaller surveyors I talked to just rented it on an as-needed basis) are the
Continuously Operating Reference Stations, which is a network of ground-based
stations of defined positions which are used to refine GPS coordinates
relative to the National Spatial Reference System:
[https://www.ngs.noaa.gov/CORS/](https://www.ngs.noaa.gov/CORS/)

------
alaithea
tl;dr Australia moves north by about the speed your hair and fingernails grow.

~~~
BurningFrog
West Iceland drifts west, and east Iceland drifts east, resulting in a 2cm
widening per year: [https://icelandmag.is/article/how-fast-iceland-growing-
due-t...](https://icelandmag.is/article/how-fast-iceland-growing-due-tectonic-
plates-drifting-apart)

~~~
notJim
Well that's one way to tackle the over-tourism problem.

