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<div class="moz-cite-prefix">On 7/31/2016 5:58 AM, Nyall Dawson
wrote:<br>
</div>
<blockquote
cite="mid:CAB28Asg6pF1LD_ZKH7s_Eq02jHAUd8sQMHw+4Q4GU5rVgk9utA@mail.gmail.com"
type="cite">
<p dir="ltr">On 30 Jul 2016 10:34 PM, "Timothy Ney" <<a
moz-do-not-send="true" href="mailto:neyfamily1@gmail.com">neyfamily1@gmail.com</a>>
wrote:<br>
><br>
> I am a professional surveyor with knowledge of the changing
coordinates. What you are referring to is the adoption of
MGA2020. To be implemented 1 January 2017. As mentioned below
the new system we consider plate drift, at approximately 7cm per
year. The most important element is that the new system will be
earth centred using the ITRF whereas AMG66, AMG84 and GDA94 were
plate centred. On 1 January 2017, all physical marks will be
given a new set of coordinates, up to about 1.6m different to
GDA94. For a while, two systems will run similtanously, the new
plate and earth centred systems. Eventually, the plate centred
coordinates will be phased out. It is expected that an
adjustment will be conducted each year, and coordinates updated.
</p>
<p dir="ltr">I'm struggling to find any information about software
support of GDA2020. The icsm FAQ has no mention of this, and I
can't find anything relevant re GDA2020 and the widely used open
source libraries like proj4 and GDAL.</p>
<p dir="ltr">Can anyone help illuminate?</p>
<p dir="ltr">Nyall</p>
</blockquote>
<br>
There are 3 problems/questions...<br>
<u><br>
</u><u>Data Storage Datum</u><br>
At present OSM uses WGS84. Will that change? In the short term
probably not. This keeps it 'simple'. <br>
<br>
<u>Data Entry - Datum</u><br>
Again OSM tries to use WGS84. If that changes then translation
between datums will be required, if one or both datums are earth
centric then the date of the measurement will be required for the
translation.<br>
<br>
<u>Data use - Datum</u><br>
If the output datum is different from the stored data of OSM again
translation will be required. <br>
<br>
If the output datum is earth centric then the date of the applied
correction should be stated on the output map (as well as the datum
used). <br>
Prediction; <br>
Paper maps produced using an earth centric datum will use a date
some time in the future, about halfway along the predicted usable
life time of the map. <br>
'Computerised' maps may adjust their output for the current date...
or use a fixed date just like the paper map above. <br>
<br>
In any short term these maps will not produce any sizable error.
Most maps are updated from time to time .. so the positional errors
will probably be acceptable to the general population during the
lifetime of the map/s. <br>
<br>
<u>Software</u><br>
Commercial proprietary software will probably not be publicised
other than its capability to use earth centric datums. There will
need to be an accepted storage format that incorporated the data of
the measurement as well as the datum, that may come out publicly as
a 'standard'. <br>
Free ware software will lag behind as usuall. <br>
<br>
<blockquote
cite="mid:CAB28Asg6pF1LD_ZKH7s_Eq02jHAUd8sQMHw+4Q4GU5rVgk9utA@mail.gmail.com"
type="cite">
<p dir="ltr">><br>
> Given that most modern GPS systems in phones, cars etc can
only achieve accuraries of 1-3 metres, it will be quite some
time before old data will no longer align with the GPS. It
should also be noted that most systems including Google use the
ITRF, or some reference to it. <br>
><br>
> In summary, the impact to most internet mapping systems
will be minimal. Even for surveyors, who is the coordinate
information, the update will have minimal impact, as we tend to
work in small areas, where coordinates are relative only. The
big players are those doing broad scale mapping and other
regional wide work. See here for more information.<br>
><br>
> <a moz-do-not-send="true"
href="http://www.icsm.gov.au/gda2020/faqs-2.html">www.icsm.gov.au/gda2020/faqs-2.html</a><br>
><br>
><br>
><br>
> On Sat, 30 Jul 2016 at 10:03 PM, <<a
moz-do-not-send="true"
href="mailto:talk-au-request@openstreetmap.org">talk-au-request@openstreetmap.org</a>>
wrote:<br>
>><br>
>> Send Talk-au mailing list submissions to<br>
>> <a moz-do-not-send="true"
href="mailto:talk-au@openstreetmap.org">talk-au@openstreetmap.org</a><br>
>><br>
>> To subscribe or unsubscribe via the World Wide Web,
visit<br>
>> <a moz-do-not-send="true"
href="https://lists.openstreetmap.org/listinfo/talk-au">https://lists.openstreetmap.org/listinfo/talk-au</a><br>
>> or, via email, send a message with subject or body
'help' to<br>
>> <a moz-do-not-send="true"
href="mailto:talk-au-request@openstreetmap.org">talk-au-request@openstreetmap.org</a><br>
>><br>
>> You can reach the person managing the list at<br>
>> <a moz-do-not-send="true"
href="mailto:talk-au-owner@openstreetmap.org">talk-au-owner@openstreetmap.org</a><br>
>><br>
>> When replying, please edit your Subject line so it is
more specific<br>
>> than "Re: Contents of Talk-au digest..."<br>
>><br>
>><br>
>> Today's Topics:<br>
>><br>
>> 1. Australia "changing coordinates" (Andy Mabbett)<br>
>> 2. Re: Australia "changing coordinates" (Warin)<br>
>> 3. Re: Australia "changing coordinates" (Andrew
Harvey)<br>
>> 4. Re: Australia "changing coordinates" (Warin)<br>
>><br>
>><br>
>>
----------------------------------------------------------------------<br>
>><br>
>> Message: 1<br>
>> Date: Fri, 29 Jul 2016 13:40:45 +0100<br>
>> From: Andy Mabbett <<a moz-do-not-send="true"
href="mailto:andy@pigsonthewing.org.uk">andy@pigsonthewing.org.uk</a>><br>
>> To: <a moz-do-not-send="true"
href="mailto:talk-au@openstreetmap.org">talk-au@openstreetmap.org</a><br>
>> Subject: [talk-au] Australia "changing coordinates"<br>
>> Message-ID:<br>
>> <CABiXOE=95mWdWn1P4SvG3ekrRktk0PEvhGNqZ=<a
moz-do-not-send="true"
href="mailto:c2vgxrbHHEcA@mail.gmail.com">c2vgxrbHHEcA@mail.gmail.com</a>><br>
>> Content-Type: text/plain; charset=UTF-8<br>
>><br>
>> See you when you reach England ;-)<br>
>><br>
>> <a moz-do-not-send="true"
href="http://www.bbc.co.uk/news/technology-36912700">http://www.bbc.co.uk/news/technology-36912700</a><br>
>><br>
>> But seriously: what impact might this have, on OSM?<br>
>><br>
>> --<br>
>> Andy Mabbett<br>
>> @pigsonthewing<br>
>> <a moz-do-not-send="true"
href="http://pigsonthewing.org.uk">http://pigsonthewing.org.uk</a><br>
>><br>
>><br>
>><br>
>> ------------------------------<br>
>><br>
>> Message: 2<br>
>> Date: Sat, 30 Jul 2016 08:40:41 +1000<br>
>> From: Warin <<a moz-do-not-send="true"
href="mailto:61sundowner@gmail.com">61sundowner@gmail.com</a>><br>
>> To: <a moz-do-not-send="true"
href="mailto:talk-au@openstreetmap.org">talk-au@openstreetmap.org</a><br>
>> Subject: Re: [talk-au] Australia "changing coordinates"<br>
>> Message-ID: <<a moz-do-not-send="true"
href="mailto:0485644d-097a-3de6-5bd2-71d49c034f60@gmail.com">0485644d-097a-3de6-5bd2-71d49c034f60@gmail.com</a>><br>
>> Content-Type: text/plain; charset=utf-8; format=flowed<br>
>><br>
>> On 7/29/2016 10:40 PM, Andy Mabbett wrote:<br>
>> > See you when you reach England ;-)<br>
>> ><br>
>> > <a moz-do-not-send="true"
href="http://www.bbc.co.uk/news/technology-36912700">http://www.bbc.co.uk/news/technology-36912700</a><br>
>> ><br>
>> > But seriously: what impact might this have, on
OSM?<br>
>> ><br>
>> Very little!<br>
>><br>
>> The change, distance wise, is upto 1.5 metres, well
within commercial<br>
>> GPS uncertainties.<br>
>><br>
>> The change is to the datum. How this will work out with
future global<br>
>> datums we will have to wait and see.<br>
>><br>
>> In another 30 years there will probably be another
change of around 1.5<br>
>> metres again.<br>
>><br>
>><br>
>><br>
>><br>
>><br>
>> ------------------------------<br>
>><br>
>> Message: 3<br>
>> Date: Sat, 30 Jul 2016 13:57:31 +1000<br>
>> From: Andrew Harvey <<a moz-do-not-send="true"
href="mailto:andrew@alantgeo.com.au">andrew@alantgeo.com.au</a>><br>
>> To: <a moz-do-not-send="true"
href="mailto:talk-au@openstreetmap.org">talk-au@openstreetmap.org</a><br>
>> Subject: Re: [talk-au] Australia "changing coordinates"<br>
>> Message-ID:<br>
>> <<a moz-do-not-send="true"
href="mailto:1469851051.2451056.680960441.20F38439@webmail.messagingengine.com">1469851051.2451056.680960441.20F38439@webmail.messagingengine.com</a>><br>
>> Content-Type: text/plain<br>
>><br>
>> On Sat, 30 Jul 2016, at 08:40 AM, Warin wrote:<br>
>> > The change, distance wise, is upto 1.5 metres,
well within commercial<br>
>> > GPS uncertainties.<br>
>> ><br>
>> > The change is to the datum. How this will work out
with future global<br>
>> > datums we will have to wait and see.<br>
>> ><br>
>> > In another 30 years there will probably be another
change of around 1.5<br>
>> > metres again.<br>
>><br>
>> As receivers become more accurate and folks start use
other ground based<br>
>> positioning technology that gives millimetre accuracy,
then that data in<br>
>> OSM will over time become more out of sync as the
tectonic plate moves<br>
>> while the coordinate system remains fixed.<br>
>><br>
>> When that happens it would be good to see a future OSM
API that lets us<br>
>> upload data in a coordinate system like GDA so that we
don't need to be<br>
>> constantly updating coordinates to reflect the move in
the techtonic<br>
>> plate.<br>
>><br>
>><br>
>><br>
>> ------------------------------<br>
>><br>
>> Message: 4<br>
>> Date: Sat, 30 Jul 2016 16:22:42 +1000<br>
>> From: Warin <<a moz-do-not-send="true"
href="mailto:61sundowner@gmail.com">61sundowner@gmail.com</a>><br>
>> To: <a moz-do-not-send="true"
href="mailto:talk-au@openstreetmap.org">talk-au@openstreetmap.org</a><br>
>> Subject: Re: [talk-au] Australia "changing coordinates"<br>
>> Message-ID: <<a moz-do-not-send="true"
href="mailto:5d2da84e-151b-b07c-4e33-57fc7a068eaf@gmail.com">5d2da84e-151b-b07c-4e33-57fc7a068eaf@gmail.com</a>><br>
>> Content-Type: text/plain; charset=utf-8; format=flowed<br>
>><br>
>> On 7/30/2016 1:57 PM, Andrew Harvey wrote:<br>
>> > On Sat, 30 Jul 2016, at 08:40 AM, Warin wrote:<br>
>> >> The change, distance wise, is upto 1.5 metres,
well within commercial<br>
>> >> GPS uncertainties.<br>
>> >><br>
>> >> The change is to the datum. How this will work
out with future global<br>
>> >> datums we will have to wait and see.<br>
>> >><br>
>> >> In another 30 years there will probably be
another change of around 1.5<br>
>> >> metres again.<br>
>> > As receivers become more accurate and folks start
use other ground based<br>
>> > positioning technology that gives millimetre
accuracy, then that data in<br>
>> > OSM will over time become more out of sync as the
tectonic plate moves<br>
>> > while the coordinate system remains fixed.<br>
>> ><br>
>> > When that happens it would be good to see a future
OSM API that lets us<br>
>> > upload data in a coordinate system like GDA so
that we don't need to be<br>
>> > constantly updating coordinates to reflect the
move in the techtonic<br>
>> > plate.<br>
>><br>
>> Sigh.<br>
>><br>
>> Simply changing from AGD66 to GDA94 can produce a
change of around 100 metres in location of a coordinate.<br>
>> So a change in datum can correct the drift without
changing the coordinates.<br>
>><br>
>><br>
>> From the above you can see that OZ moves at upto about
50 mm per year.<br>
>><br>
>> At present there is no datum system that 'drifts' over
time, that would give a system that would need little alteration
and fewer of them.<br>
>><br>
>> People who require the accuracy take into account the
drift (usually professional surveyors with very expensive
receivers, antennas etc.).<br>
>><br>
>></p>
</blockquote>
<p><br>
</p>
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