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Dan Jaksa

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Dan Jaksa last won the day on November 26 2018

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  1. Dan Jaksa

    AUSGeoid 2020 Files

    Thanks David, Here's the response from Geoscience Australia's Geoid Team: ---------------- Unfortunately the win.dat format doesn’t permit additional columns. If the uncertainties were added, the various software packages that, among other things, interpolate the AUSGeoid2020 files to user required latitude and longitude coordinates, would need to be updated and then they wouldn’t be backwards compatible with older geoid models. It was safer to produce two files and avoid the additional problems associated with format changes. Yes, you're right about the links; they will be updated. However, they shouldn’t actually make any difference for users that are using the model onshore, as the model is only valid onshore, so this shouldn’t be an issue for users. The uncertainty offshore is set to zero so that users understand that the model is invalid offshore. ---------------- Please let me know if you need further help. Kind Regards Dan
  2. Dan Jaksa

    WGS84 -> GDA2020

    Thanks Nathan, Dpending on your position uncertainty, you can simply assume that your WGS84 coordinates are compatible with GDA2020 coordinates. This uncertainty is of the order of 3 metres or more. There are EPSG parameters that may help. Please see the "GDA2020 Technical Specifications" tab: http://www.ga.gov.au/scientific-topics/positioning-navigation/datum-modernisation However, please note that WGS84 is an Earth-Centred, Earth-Fixed, dynamic datum, where coordinates referenceing any of the 6 versions of WGS84 change with time. Unfortunately, WGS84 is also used as the name of its reference frame and ellipsoid, only to confuse users even more. More information can be found here: http://www.ga.gov.au/scientific-topics/positioning-navigation/wgs84 Kind Regards Dan
  3. Dan Jaksa

    Farewell and thanks for all the help

    Onya Mark, Thanks for all your help and advice. Good luck with your next chellange. Kind Regards Dan
  4. Dan Jaksa

    GDA202 Transformation and Conversion Tools

    Hi All, Please note that the new version of GDAy is now available to download from the ICSM Australia GitHub Repository. Please see the ICSM Software and plugins webpage for further details: http://www.icsm.gov.au/datum/gda-transformation-products-and-tools/software-and-plugins Kind Regards, Dan
  5. Dan Jaksa

    Beyond GDA2020

    Thanks Mark, It's great to hear that you are moving to GDA2020 and thinking about the future time-dependent reference frame. The information needed to compute time-referenced coordinates is available in the ICSM GDA2020 Technical Manual. The ITRF2014 reference frame is currently used. Check-out chapters 2 and 3 - specifically sections 2.2 and 3.3. Note that GDA2020 and ITRF2014 will be coincident on 2020.0, which is at 00:00:00 (midnight) on 1 January 2020. Also, as ITRF2014 is the reference frame GDA2020 is based, the future ATRF will be similarly referenced. The ICSM Permanent Committee on Geodesy is currently preparing the strategies and processes needed to continually realize the ATRF. However, please feel free to continue to raise questions regarding the ATRF, as this will help us in understanding user needs and potential issues around the future dynamic system. Kind Regards, Dan
  6. Dan Jaksa

    Use of GDA2020 logo

    Thanks Jeremy, ICSM is currently working on a GDA2020 logo policy that will define the rules around its use. However, in the interim, it would be acceptable to use the logo where the product was derived directly with reference to GDA2020, or where the product’s spatial uncertainty is greater than the spatial change resulting from a GDA94 to GDA2020 transformation. In these instances, the word "compatible” is implied by the logo and is therefore not required. This is subject to any future conditions that may require you to make appropriate changes defined by the GDA2020 logo policy. Please email icsm@ga.gov.au to obtain a copy of the logos.
  7. Dan Jaksa

    GDA2020 Metadata (extending ISO 19115)

    Hi Mark, My colleagus got back to me and advised that ISO 19115-1:2014 has all the fields that are required to accomodate GDA2020 and ATRF. Older versions do not. Please ensure that you're using the lastest version: https://www.iso.org/standard/53798.html I hope this helps, but please get back to me if you need any further information. Kind Regards Dan
  8. Dan Jaksa

    GDA2020 Metadata (extending ISO 19115)

    Thanks Mark, I represent Geoscience Australia on the Control Body for ISO 19127 Geographic information — Geodetic register and ISO 19111 Geographic information — Spatial referencing by coordinates — Part 1: Fundamentals which is ensuring that GDA2020 and ATRF-style dynamic datums are accommodated. I’m also working on ISO 19161 Geographic information/Geomatics — The International Terrestrial Reference System (ITRS): definition, realizations, dissemination, but this is somewhat unrelated. I recall looking at ISO 19115.1:2015 Geographic Information – Metadata Part 1: Fundamentals and ISO 19115.3:2016 Geographic Information – Metadata Part 3: XML schema implementation for fundamental concepts, but I’m not on any working groups/committees regarding these standards. I have asked some others within Geoscience Australia as to whether they know of any work on 19115 and will get back to you with an answer soon. Kind Regards Dan
  9. Dan Jaksa

    AUSPOS 2.3 - Derived AHD Positional Uncertainity

    Thanks for the question Kerry, As defined in the ICSM Standard for the Australian Survey Control Network Special Publication 1 (http://www.icsm.gov.au/geodesy/sp1.html), Positional Uncertainty is defined as the uncertainty of the horizontal and/or vertical coordinates of a survey control mark with respect to datum. In the case of the AUSPOS 2.3 computation, AUSGeoid2020 is used to compute AHD. AUSGeoid2020 is the Australia-wide gravimetric quasigeoid model that has been a posteriori fitted to the AHD. For reference, derived AHD is always determined from the GDA2020 coordinates. In the GDA94 section of the AUSPOS 2.3 report, AHD values are assumed to be identical to those derived from GDA2020. The uncertainties in Derived AHD are computed using the approach as defined in the paper The first Australian gravimetric quasigeoid model with location-specific uncertainty estimates by W. E. Featherstone, J. C. McCubbine, N. J. Brown, S. J. Claessens, M. S. Filmer, J. F. Kirby (https://link.springer.com/article/10.1007/s00190-017-1053-7). Essentially, the uncertainties in the Derived AHD values relate to the combination of the uncertainty in the GNSS observations, levelling data used to define AHD and the gravimetric quasigeoid. The reason AUSGeoid2020 derived AHD heights have an uncertainty of 10 – 20 cm is because AUSGeoid2020 is the first model to rigorously compute uncertainty from all sources. AUSGeoid09 did not include uncertainty from the gravimetric quasigeoid. I hope this helps, but if not, please feel free to re-post. Kind Regards, Dan
  10. Thanks Kerry, The process to transform from AGD66 or AGD84 coordinates to GDA2020 coordinates is to first transform them to GDA94 (details and tools can be found here: http://www.icsm.gov.au/gda/tech.html) and then to use the parameters and formulae published in the GDA2020 Interim Release Note (http://www.icsm.gov.au/gda2020/index.html) to transform from GDA94 to GDA2020 coordinates. As mentioned in the first post on this topic, tools to convert between GDA94 and GDA2020 and vice-versa is currently being developed by Geoscience Australia in conjunction with other jurisdictions and the Cooperative Research Centre Spatial Information. These tools are expected late April/early May.
  11. Dan Jaksa

    EPSG and MGA definitions

    Thanks Quickclose, The conventions that are applied to both GDA94 and GDA2020 and their respective projected coordinate reference system follow the standard set out in ISO 19127 (see section C.7 Element Naming, C.7.8 Projected coordinate reference systems). It was advised by the EPSG to follow this approach so as not to unnecessarily create 15 new map projections for the Map Grid of Australia that are no different to the existing ones used for GDA94. Hence the naming convention within the EPSG is GDA2020 / MGA Zone xx. Nevertheless, the new GDA2020 Technical Manual will define GDA2020 grid coordinates as Map Grid of Australia 2020 (MGA2020). I hope this makes it clear, but please repost if you need more help.
  12. Dan Jaksa

    Qld Mining Acts & Regulations - GDA

    Yes, thanks Kerry. Quite right. Interestingly, AGD66 was only used as an identifier after AGD84 was released. The biggest changes from AGD66 to AGD84 were in northern Queensland, with over 5 metres shift. I'm sure that this wont be the case between GDA94 and GDA2020. I enjoy reading old geodetic papers. Here's one that you might like to read too. The Geodetic Adjustment of Australia, 1963-1966 by A. G. Bomford. There is a great quote in this paper: "Surveyors are paid to get the right answer and the wrong answer scores nought; yet the only man who can be quite certain of making no mistakes is the man who says nothing and does nothing." So thanks for posting and keeping us all well informed.
  13. Dan Jaksa

    Qld Mining Acts & Regulations - GDA

    Hi Kerry, Any legislative changes will be driven by the jurisdiction to which it applies; in this case, the Queensland Government. The Queensland Government will need to review its legislation and apply the appropriate amendments. There is a Queensland Government representative on the GDA Modernisation Implementation Working Group, who will help in this activity. You have highlighted the GDA reference defined within the regulation as “GDA means Geocentric Datum of Australia which is a system of earth-centred datum used for mapping.” I must preface my comments by stating that I am not providing a legal opinion. The current Recognized-value standard of measurement of position 2012 (No.1) provides the definition of GDA as (https://www.legislation.gov.au/Details/F2012L00800): “The Geocentric Datum of Australia is realised by the coordinates of the following Australian Fiducial Network geodetic stations referred to the GRS80 ellipsoid determined within the International Earth Rotation Service Reference Frame 1992 (ITRF1992) at the epoch 1994.0” When this was published, there was only one Geocentric Datum of Australia, as the earlier reference system was named the Australian Geodetic Datum and there was no need to distinguish them by adding their respective year of coordinate realisation. The soon to be adopted Recognized-value standard of measurement of position 2017 will need to distinguish between the GDA at the 1994.0 epoch from the new GDA at the 2020.0 epoch. This will be the case – the definition will be “Geocentric Datum of Australia 2020”.
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