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preferred methods to transform coordinates between GDA94 and GDA2020

  • 1.  preferred methods to transform coordinates between GDA94 and GDA2020

    Posted 07-01-2021 00:36
    Hi all, Just wondering if anyone has gone through this process and would be happy to share their experience. I work for a water utility company and use Mapinfo Pro.

    We will need to, at some stage, sooner rather than later,  migrate from GDA 94 to GDA 2020 as you all know. The senior GIS that managed the transformation some 10 years ago, has left the company and I will be the one trying to sort this out and I am not sure how to go about.

    Any help would be very appreciated.

    Regards
     Virginia

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    Virginia Ricardo
    [GIS/Draftsperson]
    Riverina Water County Council
    Wagga Wagga NSW
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  • 2.  RE: preferred methods to transform coordinates between GDA94 and GDA2020

    Posted 07-04-2021 19:33
    Hi Virginia,

    Waverley Council migrated across at the start of the year. Couple steps along the way:

    - Catalogue all spatial .tab/.shp/arcgisFeatureServer files or SQLtables into a single spreadsheet; these are all the files needed to migrate across to GDA2020. Also, note down for any of these files whether if contains elevation/height, and possibly what the current native projection is

     - I used FME to reproject in bulk - Waverley has couple hundred tab files and we wanted to migrated to SQL, therefore FME was the obvious choice. It caters to scenarios when the source data is in AGD or Lat/Long.

    - If you have files in AGD, you would want to reproject it to gda94 first - details here.

    - Once the catalogue is ready, I ran FME across all the files on the list to reproject them. That said, you might be able to get away with using just MapInfo if you have a small number of files to convert

    - It is recommended to reproject using 'GDA94_to_GDA2020_conformal_and_distortion' . Further details here.I dont believe Mapinfo allows for 'conformal + distortion' but the difference is minor, depending on who is using it, but obviously go with conformal and distortion if available. In FME thats using [CsmapReprojector] and transform with {'GDA94_to_GDA2020_conformal_and_distortion_NTv2_Grid_FME'}; .

    - Waverley uses NSWSpatial's incremental feed so that is another thing to consider. I believe they could be rolling out Feeds in gda2020 any time now. Unfortunately at the start of the year, it was still in gda94 so I had to convert these tables too on a nightly basis.

    I can step through the process in more detail if you like or over the phone - email . If you have FME, Im happy to share the FME workbench too, and anyone else interested

    Cheers,
    Mat

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    Mat Chen
    Waverley Council
    BONDI JUNCTION NSW
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  • 3.  RE: preferred methods to transform coordinates between GDA94 and GDA2020

    Posted 07-04-2021 21:12
    Hi Mat,

    Thank you so very much for the detailed explanation you have provided me. I am really grateful. I will talk to our  IT and try to start the process. I might give you a call if I run into some difficulties.

    Kind Regards
    Virginia

    ------------------------------
    Virginia Ricardo
    [GIS/Draftsperson]
    Riverina Water County Council
    Wagga Wagga NSW
    ------------------------------



  • 4.  RE: preferred methods to transform coordinates between GDA94 and GDA2020

    Posted 07-05-2021 08:09
    Hi Virginia & Mat,

    Viriginia - I thought I might just add to Mat's helpful process by mentioning that if going with FME and writing spatial data to SQL Server you will need the more expensive Database Edition of FME Desktop rather than the Professional Edition.

    Mat - Did you do anything with your imagery files?


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    James Nolet
    Dooley Mitchell & Morrison Pty Ltd
    Mentone, VIC, Australia
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  • 5.  RE: preferred methods to transform coordinates between GDA94 and GDA2020

    Posted 07-05-2021 20:17
    Hi James,

    You guys are awesome! Thank you for helping out as well. I will make sure we take this into consideration before starting our process.  I am hoping to have all sorted rather sooner then later.

    Once again thank you both very much.




    ------------------------------
    Virginia Ricardo
    [GIS/Draftsperson]
    Riverina Water County Council
    Wagga Wagga NSW
    ------------------------------



  • 6.  RE: preferred methods to transform coordinates between GDA94 and GDA2020

    Posted 07-05-2021 22:09
    Hi James,

    Not at this stage with our aerials. I believe Waverley's aerials are mostly in epsg:3857 (I'm relatively new to Waverley council, so i might be corrected) and we use Nearmaps here too. Also, Waverley is about to roll over from Exponare to SSA and epsg:3857 is the stock standard default projection for its 'backgrounds' therefore we decided not to port over.
    A little while ago, I spoke to Matt Robinson(@ChartisTechnology) and he suggested to use 'GDALMove'

    Yes! FME DB does help make life a lot easier. I actually don't have FME DB available, and ended up using FME Desktop alongside Easyloader, a long winded method. Easyloader is solely used to upload into SQLserver and to create MI_STYLES column which ended up as an ok option

    Slightly off topic...
    James, how do you get around mapinfo allowing only one undo/redo when working with SQL data? My major pain point at the moment. I am hoping one of MapInfo's devs will read this and improve it :)

    Cheers,
    Mat


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    Mat Chen
    Waverley Council
    BONDI JUNCTION NSW
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  • 7.  RE: preferred methods to transform coordinates between GDA94 and GDA2020

    Posted 07-06-2021 04:34
    Hi Mat,

    Thanks for the information about the aerials.  Where you have older imagery files some transformation might be required, or you can rely on the GIS to re-project on the fly.  When displaying in MapInfo (or Exponare), it might be only a matter of updating the coordinates in the reference file (e.g. the TAB file).  Some imagery files have the coordinates embedded in the actual file (e.g. ecw), but I am unsure if there is a need to go to the trouble of transforming these.

    I get around the undo/redo by being very careful.  Having used MapInfo since v4.1 I'm used to this.  Back then, MS Word and other applications were the same.  One method is to save often, and make backups at regular intervals so I don't have to repeat too much work if I make a mistake.

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    James Nolet
    Dooley Mitchell & Morrison Pty Ltd
    Mentone, VIC, Australia
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