[talk-au] Talk-au Digest, Vol 109, Issue 22

Sun Jul 31 08:36:48 UTC 2016

On 31 July 2016 at 09:16, Warin <61sundowner at gmail.com> wrote:
> On 7/31/2016 5:58 AM, Nyall Dawson wrote:
>
> On 30 Jul 2016 10:34 PM, "Timothy Ney" <neyfamily1 at gmail.com> wrote:
>>
>> 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.
>
> 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.
>
> Can anyone help illuminate?
>
> Nyall
>

> 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'.
> Free ware software will lag behind as usuall.

Well - I'm trying to avoid that situation. There's no reason it
*should* lag, and a huge number of projects rely on these open source
backends.

Is there even an EPSG code assigned to this new CRS yet?

Nyall

>
>>
>> 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.
>>
>> 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.
>>
>> www.icsm.gov.au/gda2020/faqs-2.html
>>
>>
>>
>> On Sat, 30 Jul 2016 at 10:03 PM, <talk-au-request at openstreetmap.org>
>> wrote:
>>>
>>> Send Talk-au mailing list submissions to
>>>         talk-au at openstreetmap.org
>>>
>>> To subscribe or unsubscribe via the World Wide Web, visit
>>>         https://lists.openstreetmap.org/listinfo/talk-au
>>> or, via email, send a message with subject or body 'help' to
>>>         talk-au-request at openstreetmap.org
>>>
>>> You can reach the person managing the list at
>>>         talk-au-owner at openstreetmap.org
>>>
>>> When replying, please edit your Subject line so it is more specific
>>> than "Re: Contents of Talk-au digest..."
>>>
>>>
>>> Today's Topics:
>>>
>>>    1. Australia "changing coordinates" (Andy Mabbett)
>>>    2. Re: Australia "changing coordinates" (Warin)
>>>    3. Re: Australia "changing coordinates" (Andrew Harvey)
>>>    4. Re: Australia "changing coordinates" (Warin)
>>>
>>>
>>> ----------------------------------------------------------------------
>>>
>>> Message: 1
>>> Date: Fri, 29 Jul 2016 13:40:45 +0100
>>> From: Andy Mabbett <andy at pigsonthewing.org.uk>
>>> To: talk-au at openstreetmap.org
>>> Subject: [talk-au] Australia "changing coordinates"
>>> Message-ID:
>>>
>>> <CABiXOE=95mWdWn1P4SvG3ekrRktk0PEvhGNqZ=c2vgxrbHHEcA at mail.gmail.com>
>>> Content-Type: text/plain; charset=UTF-8
>>>
>>> See you when you reach England ;-)
>>>
>>>    http://www.bbc.co.uk/news/technology-36912700
>>>
>>> But seriously: what impact might this have, on OSM?
>>>
>>> --
>>> Andy Mabbett
>>> @pigsonthewing
>>> http://pigsonthewing.org.uk
>>>
>>>
>>>
>>> ------------------------------
>>>
>>> Message: 2
>>> Date: Sat, 30 Jul 2016 08:40:41 +1000
>>> From: Warin <61sundowner at gmail.com>
>>> To: talk-au at openstreetmap.org
>>> Subject: Re: [talk-au] Australia "changing coordinates"
>>> Message-ID: <0485644d-097a-3de6-5bd2-71d49c034f60 at gmail.com>
>>> Content-Type: text/plain; charset=utf-8; format=flowed
>>>
>>> On 7/29/2016 10:40 PM, Andy Mabbett wrote:
>>> > See you when you reach England ;-)
>>> >
>>> >     http://www.bbc.co.uk/news/technology-36912700
>>> >
>>> > But seriously: what impact might this have, on OSM?
>>> >
>>> Very little!
>>>
>>> The change, distance wise, is upto 1.5 metres, well within commercial
>>> GPS uncertainties.
>>>
>>> The change is to the datum. How this will work out with future global
>>> datums we will have to wait and see.
>>>
>>> In another 30 years there will probably be another change of around 1.5
>>> metres again.
>>>
>>>
>>>
>>>
>>>
>>> ------------------------------
>>>
>>> Message: 3
>>> Date: Sat, 30 Jul 2016 13:57:31 +1000
>>> From: Andrew Harvey <andrew at alantgeo.com.au>
>>> To: talk-au at openstreetmap.org
>>> Subject: Re: [talk-au] Australia "changing coordinates"
>>> Message-ID:
>>>
>>> <1469851051.2451056.680960441.20F38439 at webmail.messagingengine.com>
>>> Content-Type: text/plain
>>>
>>> On Sat, 30 Jul 2016, at 08:40 AM, Warin wrote:
>>> > The change, distance wise, is upto 1.5 metres, well within commercial
>>> > GPS uncertainties.
>>> >
>>> > The change is to the datum. How this will work out with future global
>>> > datums we will have to wait and see.
>>> >
>>> > In another 30 years there will probably be another change of around 1.5
>>> > metres again.
>>>
>>> As receivers become more accurate and folks start use other ground based
>>> positioning technology that gives millimetre accuracy, then that data in
>>> OSM will over time become more out of sync as the tectonic plate moves
>>> while the coordinate system remains fixed.
>>>
>>> When that happens it would be good to see a future OSM API that lets us
>>> upload data in a coordinate system like GDA so that we don't need to be
>>> constantly updating coordinates to reflect the move in the techtonic
>>> plate.
>>>
>>>
>>>
>>> ------------------------------
>>>
>>> Message: 4
>>> Date: Sat, 30 Jul 2016 16:22:42 +1000
>>> From: Warin <61sundowner at gmail.com>
>>> To: talk-au at openstreetmap.org
>>> Subject: Re: [talk-au] Australia "changing coordinates"
>>> Message-ID: <5d2da84e-151b-b07c-4e33-57fc7a068eaf at gmail.com>
>>> Content-Type: text/plain; charset=utf-8; format=flowed
>>>
>>> On 7/30/2016 1:57 PM, Andrew Harvey wrote:
>>> > On Sat, 30 Jul 2016, at 08:40 AM, Warin wrote:
>>> >> The change, distance wise, is upto 1.5 metres, well within commercial
>>> >> GPS uncertainties.
>>> >>
>>> >> The change is to the datum. How this will work out with future global
>>> >> datums we will have to wait and see.
>>> >>
>>> >> In another 30 years there will probably be another change of around
>>> >> 1.5
>>> >> metres again.
>>> > As receivers become more accurate and folks start use other ground
>>> > based
>>> > positioning technology that gives millimetre accuracy, then that data
>>> > in
>>> > OSM will over time become more out of sync as the tectonic plate moves
>>> > while the coordinate system remains fixed.
>>> >
>>> > When that happens it would be good to see a future OSM API that lets us
>>> > upload data in a coordinate system like GDA so that we don't need to be
>>> > constantly updating coordinates to reflect the move in the techtonic
>>> > plate.
>>>
>>> Sigh.
>>>
>>> Simply changing from AGD66 to GDA94 can produce a change of around 100
>>> metres in location of a coordinate.
>>> So a change in datum can correct the drift without changing the
>>> coordinates.
>>>
>>>
>>>  From the above you can see that OZ moves at upto about 50 mm per year.
>>>
>>> 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.
>>>
>>> People who require the accuracy take into account the drift (usually
>>> professional surveyors with very expensive receivers, antennas etc.).
>>>
>>>
>
>
>
> _______________________________________________
> Talk-au mailing list
> Talk-au at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk-au
>