
Australia will update its latitude and longitude after moving 1.5m - jerryr
http://www.abc.net.au/news/2016-07-28/why-it-matters-that-australias-coordinates-are-moving/7668014
======
planteen
>Self-driving cars, for example, must have infinitesimally precise location
data to avoid accidents.

I'm sure surveyors, machinists, and physicists would be interested in how
"infinitesimal" location data can be obtained. This article doesn't really
spell out what is going on. Did Australia use some other datum than WGS84 and
now they changed it?

~~~
jonknee
I don't think this is even true though, it's not like self driving cars are
driving on GPS alone. They use GPS to know generally where they are and then
sensor data to actually navigate in the space. That said there aren't a ton of
mapping providers so rolling out a change should not be very hard.

~~~
adrianratnapala
But why would you bet the farm on the assumption that there is no bug anywhere
in important code that takes GPS too literaly.

True, the GPS coordinates might have a errors much greater than this 1.5
metres. But:

(1) bugs can be devious, and I don't trust them to respect this particular
insurmountable barrier, and

(2) this error accumulates roughly linearly over time and it is better to make
frequent small changes than to wait until you have to make a big, panicked
one.

~~~
jonknee
Sure, but this particular example is pure FUD in regards to self-driving cars.
That's not to say there are no bugs, but this sort of GPS inaccuracy is not an
issue for safe autonomous travel.

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taneq
DON'T USE GPS ALONE FOR SELF DRIVING CARS.

Not even DGPS. Really. Don't. A ton of metal moving under its own volition
really needs to be looking at the things around it, directly, using some kind
of vison. Cameras are good.

~~~
MiguelHudnandez
It would be criminally negligent to use GPS for any control decisions in a
self-driving vehicle.

Aside from wishy-washy long term tasks like what route to take, or which
street has traffic, GPS simply cannot be used.

GPS can fail, be jammed, or lose accuracy. I can't imagine there is any risk
of any production vehicles using GPS alone. Certainly GPS matching physical
reality will be helpful, but no car is going to drive on a sidewalk and plow
through fire hydrants because GPS was off by 1.5 meters.

Before a car can enter a physical space, it should verify with at least two
local, independent, physical sensors that the intended space is unoccupied and
that no detectable objects are on a trajectory to occupy that space. Our
brains do these calculations very easily and with minimal conscious thought.
However, our brains' attentiveness and accuracy leave much to be desired.

~~~
notahacker
I think the potential issue with GPS being a couple of metres out issue is
less cars driving through fire hydrants and more the car driving down what GPS
thinks is the correct route and looks like a nice open stretch of road to the
computer vision, but is in fact the wrong lane...

~~~
bbradley406
A common problem I've had with standalone GPS units is that they get confused
when two roads are very close to one another. Highway overpasses, on-ramps and
off-ramps, routes right next to highways, etc. You wouldn't want your self
driving car to think it's on a freeway and should do 65 when you're really on
the dirt farm road right next to it.

------
djsumdog
Reminds me of the great Melbourne earthquake of 2012. And by great I do mean
my flatmate came to my room and said, "Was that an earthquake?" "um....maybe.
I .. I think so?"

My fizzy drink fell over. It was a mess. Never forget!

~~~
Analemma_
Heh, the East Coast of the US had a similar experience in 2011, leading to
great jokes like
[http://wp.patheos.com.s3.amazonaws.com/blogs/friendlyatheist...](http://wp.patheos.com.s3.amazonaws.com/blogs/friendlyatheist/files/2012/08/Never-
Forget.jpg)

------
wongarsu
>Self-driving cars, for example, must have infinitesimally precise location
data to avoid accidents.

With GPS having at best three metres accuracy? It's nice that they keep their
data up to date, but I'm not so sure self-driving cars have anything to do
with it.

~~~
tachim
Differential GPS can hit ~10cm level accuracy.

~~~
djsumdog
Those are also $3k ~ $5k and have to be configured to use a GPS base station.
A professor once let us borrowed his. It had a full backpack and was
supposedly accurate to 3cm using the airport as our base station.

~~~
extrapickles
DGPS is much cheaper than it used to be as it is a feature of most GPS
chipsets, though its poorly documented how you enable it. You also need to
provide a serial data link between the two GPS units (for most applications
this is over RF).

Also, from my understanding, you only know the relative position of the two
stations accurately, not the absolute world location.

------
a3n
> Australia will update its latitude and longitude after moving 1.5m

I imagine a guy in a Commodore's outfit climbing a ladder to some bridge (but
on the land), making an observation, swatting the dust off a log book with his
hanky, making an entry, closing the book, looking around with satisfaction,
and then climbing back down the ladder.

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guelo
Here's an animation showing Australia crashing into Indonesia in 25 million
years and into China in 50 million years.

[https://www.youtube.com/watch?v=2It3ETk2MGA](https://www.youtube.com/watch?v=2It3ETk2MGA)

------
205guy
Wow, 7cm/yr seems fast. I thought I read once it was 1-2 cm/yr, about the same
as your fingernails grow (it was a rule of thumb). Probably different plates
are moving at different speeds.

I think it's exciting to see examples of continental drift on the human scale.
Usually, all the models talk about Pangea and hundreds of millions of years,
and our brains have trouble seeing the context.

But I wonder if we don't need a more flexible system, maybe like leap days and
leap seconds that get added much more often. Or just have a global reference
and an offset for the local datum that can be updated yearly.

~~~
gkya
"1-2 cm/yr"

IIRC that's the speed South Africa and South America are moving away from each
other.

------
ungzd
How is it related to GPS? Usually GPS devices return coordinates in WGS84
which will not be changed. They're just updating old maps which was based on
their local datums?

~~~
nraynaud
they are basically changing the official WGS84 coordinates of a number of
famous Point Of Interest.

The way they do it that they measure the position of some reference point in
WGS84 on every tectonic plate, then they measure the relative position of a
bunch of point of interest from the local reference point. At a regular
interval, they re-measure the actual coordinates of the reference point in
WGS84, and that automatically moves all of its dependent points of interest in
WGS84. Tectonic plate movement is why WGS84 is not always the best way to
store your points of interest, keeping them in the local reference also helps
propagation when an update occurs.

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mmahemoff
Wouldn't this also be relevant to boring old human-driving cars and loads of
other applications?

~~~
maxerickson
Humans don't really navigate at a meter scale when they are driving. A nav
system giving directions 19.9 seconds before the turn isn't going to be
noticeably different than one doing it 20 seconds before the turn.

~~~
varjag
One would really hope the steering in self driving cars is derived from
sensory input and not nav system waypoints.

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perseusprime11
In a few million years, it would have moved so much that it will cut down
commute times from U.S to Australia. Obviously riffing here but I am curious
where it will end up in a few million years.

~~~
gkya
See this comment for a video simulation:
[https://news.ycombinator.com/item?id=12189301](https://news.ycombinator.com/item?id=12189301)

It'll seemingly hit Asia in the guts while part of siberia leaves with Korea
moving east. And my poor little city's gonna get squashed and move north to
replace some cold Russian city...

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jjp
Slightly more detail - [http://www.abc.net.au/news/2016-07-28/why-it-matters-
that-au...](http://www.abc.net.au/news/2016-07-28/why-it-matters-that-
australias-coordinates-are-moving/7668014)

~~~
sctb
Thanks, we updated the link from [http://www.cnet.com/news/australia-has-
moved-1-5m-so-its-upd...](http://www.cnet.com/news/australia-has-
moved-1-5m-so-its-updating-its-location-for-self-driving-cars/).

