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TasSurveyor

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TasSurveyor last won the day on April 4 2018

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  1. TasSurveyor

    Transformation GSB File

    Hi, Both grids definitely have national coverage, the extent of which is shown in Figure 3.3. in https://www.icsm.gov.au/sites/default/files/GDA2020TechnicalManualV1.1.1.pdf . I am guessing the reason you have queried this is because you have seen the results like I have when I dragged and dropped the .gsb files in QGIS. Doing this, only the WA portion of the grid displays as a very pretty raster. However, this isn't because it only includes WA but rather is related to the structure of the national grid, which was built up from separate grids originally developed for jurisdiction testing. They aren't technically "sub-grids" in the manner allowed for under NTv2 format but QGIS only displays the WA partition when i do my simple drop and drag. However, when you actually use the grid for a transformation the full national data set is applied in the software i have used it in. Recommend that you sanity check your transformation for some sample points against the results of the national online service at http://positioning.fsdf.org.au/ if you want some piece of mind. cheers, Scott.
  2. Hi Gary, I don't know anything about Oracle, but i did do something similar with QGIS v2.x. The values you need to define the GDA2020 datum and include to enable a 7 parameter transformation from GDA94 to GDA2020 (and also allow the software to apply the inverse) are available from the GDA2020 technical manual. The transformation parameters are in table 3.2. http://www.icsm.gov.au/sites/default/files/GDA2020TechnicalManualV1.1.1.pdf A very important point to note is that there are two conventions adopted for the rotation signs, and the convention adopted in Aus / the GDA Tech manual (section 2.2.1) is possibly not the convention adopted in Oracle. For a practical approach to determine this choice, my advice is look at the signs applied in the Oracle table for the AGD66 to GDA94 transformation values (or AGD84 to GDA94) and compare them with the signs noted in Appendix B2 or Appendix B3 of the GDA2020 tech manual. If the rotation sign in Oracle for these transformations is reversed from those in the manual then you will most likely need to adopt the same approach for GDA94 to GDA2020. In any case, make sure you check some sample results using one of the tools on the ICSM web page - http://www.icsm.gov.au/datum/gda-transformation-products-and-tools If Oracle allows for Ntv2 grids and you want to include these I suggest you follow the same approach and look for examples of how other Aus NTv2 grids have been applied, including where any of the grids are located in the directory structure. Hope this helps. Scott.
  3. TasSurveyor

    GDA2020 Legislation/Mandate

    Hi Mark, At present, GDA2020 has been defined and individual jurisdictions are at various stages in the process towards its practical implementation. Currently, there is no "legislation" mandating the move to GDA2020 that i know of in any Australian jurisdiction. The question of intent in relation to this issue, and more particularly where jurisdictions are at in relation to practical implementation, is best asked directly of your jurisdiction - you can try that at the appropriate forum page or directly via contacts listed on the GDA2020 related www pages of your responsible jurisdiction agency. Regards, Scott
  4. TasSurveyor

    AusGeoid xx - GSB file reader/convertor

    Hi Kerry, At the bottom of this page http://www.icsm.gov.au/gda/soft.html under the Ausgeoid products and tools heading you will find the downloadable interpolation software developed by Dr Roger Fraser.
  5. TasSurveyor

    GDA2020 officially released

    Leading up to and in conjunction with the official release of GDA2020 in December 2017 http://www.icsm.gov.au/gda/news.html the datum section of the ICSM website has seen quite a few changes to its structure and content - check it out at http://www.icsm.gov.au/gda/index.html
  6. TasSurveyor

    FME Transformers

    Hi, Note the original article on working with GDA2020 in FME https://knowledge.safe.com/articles/44498/new-australian-national-datum-gda2020-support-with.html was updated yesterday to advise on progress towards using the NTv2 grids recently released by ICSM
  7. TasSurveyor

    GDA 2020 support in Mapinfo

    Thanks Andrei, Noting that the url for the tech manual is http://www.icsm.gov.au/gda/GDA2020TechnicalManualV1.1.1.pdf All information on the national datum on the ICSM website is best accessed at from the the url with just "gda" in the path not "gda2020" i.e. http://www.icsm.gov.au/gda/.......... not http://www.icsm.gov.au/gda2020............ A bit of background is useful here - "gda2020" did feature in some urls in 2016/2017 but was changed late last year (around when GDA2020 was officially notified and tech manual v1.1 was released) to be all "gda", with a redirect implemented from the "gda2020" addresses. Many websites and shared hotlinks pointed to the path with "gda2020" in it but historically the national datum and tech manual info was always available at the "gda" url. However, the Tech manual was changed to v1.1.1 yesterday (8 January), so this must have led to the redirect for v1.1 document no longer working today! regards, Scott.
  8. Hi Ian, IF you haven't had the need to follow things closely it is understandable that you thought GDA2020 was meant to be used since last January. RE the open source libraries PROJ.4 / GDAL there are still a few things that needs to be arranged to have them working appropriately with GDA2020 and the various projections used across Australia. Yes the spatial arena is great for jargon - more of it follows below sorry. The spreadsheet you refer to above is for transforming from the historic Australian plate-fixed (static) datums AGD66/84 to GDA94 and wont be updated to include GDA94 > GDA2020, which is also a static or plate-fixed datum. Transformations between static datums only require 7 parameters - the time element (7 rates of of change, so 14 parameters) only comes into the picture if transforming to an "earth-fixed" reference frame like ITRF or stage 2 of Australian Datum modernisation - the ATRF. (This statement is probably clear as mud!) The introductory description is generalised to allow for both cases. The spreadsheets dealing with the 7 parameter GDA94 to GDA2020 transformation are on the ICSM github repository https://github.com/icsm-au but i would recommend having a look at the full GDA2020 tech manual http://www.icsm.gov.au/gda/tech.html first if you have the time.
  9. Hi Ian, GDA2020 isn't really available as an "operational" datum just yet - recommend review / keep an eye on the ICSM website for information about GDA2020 http://www.icsm.gov.au/gda/index.html - have you reviewed this site for status as well as the technical and explanatory information about horizontal and vertical transformations? Content will be updated and expanded when GDA2020 is officially "operational" as will the GA pages. The QGIS plugins will also deal with 2D GDA94 to GDA2020 transformations. This isn't far away. GDAL 2.2.2 doesn't implement a GDA94 <> GDA2020 transformation. In a successful transformation, the change in horizontal coordinate values should equate to 1.5 to 1.8m horizontal difference, depending on where you are in Australia. I don't quite understand the summary around the use of AUSgeoid09, in particular "the shift is ~ 0.5-1.5m" - shift in what?
  10. TasSurveyor

    FME Transformers

    Thanks for this advice Paul. The national GDA94-GDA2020 NTv2 distortion grid is now very close to be being finalised. Software providers will be notified directly when it is but the grids will be freely accessible via the method described by Alex previously. The ICSM website - http://www.icsm.gov.au/gda/grids.html will also provide background information / resources on all the Australian grids.
  11. A good article from a software providers perspective on the new USA Terrestrial Reference Frames that will replace the existing plate-fixed datums in 2022 http://blog.bluemarblegeo.com/2017/09/05/north-american-terrestrial-reference-frame-2022-replacing-nad83/?aid=EMMN0917&utm_source=newsletter&utm_medium=emil&utm_campaign=september_2017&utm_content=button .
  12. TasSurveyor

    GDA2020 Transforms & ArcGIS

    see new article by Gordon Sumerling https://esriaustraliatechblog.wordpress.com/2017/06/08/gda2020-transformations-arcgis/ Explanation of difference between the two grids - Conformal and full distortion - and their usage will be available when the grids are released
  13. TasSurveyor

    Application of NTv2 distortion grid

    Hi Quickclose, Thanks for the questions. As noted in the discussion regarding distortion the most appropriate action in the circumstances outlined in your query are jurisdiction specific due to the manner in which GDA94 control (CORS and traditional ground) networks have been maintained. As Nic alludes, the statement "... I assume the NTv2 grid to be released will model the distortion between the latest adjustment(s) of GDA94 and GDA2020, not previous statewide adjustments of GDA94" doesn't hold. "Never assume and assumption" was one of the more entertaining pieces of advice I recall from one of my football coach's and in relation to jurisdictional treatment of GDA94 networks it is actually pertinent (that team did win a premiership so perhaps our coach gave very good advice - or maybe we were just a very good team!). Like NSW, the realisation of GDA94 coordinates on the Tas ground control network is largely unchanged - there is no recent statewide GDA94 network adjustment and the distortions present in the network since 2000 will be swept up and corrected by the transformation grid. You can expect further jurisdiction specific advice to be presented along with explanatory information about transformation grids when GDA2020 is officially released. It is worth noting that the issues under discussion relate more to GDA94 control network realisation than the move to GDA2020 and the transformation - users of geodetic control information on GDA94 datum need to "know their data" .
  14. TasSurveyor

    GDA2020 Interim Release note

    Thanks for noting this.
  15. TasSurveyor

    GDA2020 Interim Release note

    See the latest GMIWG update for details http://www.icsm.gov.au/gda2020/gmiwg.html
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