Hello,  I would like to understand how exactly time-dependent transformations work in ArcGIS Pro - in relation between the reference map and to the actual dataset in order to identify good data management/handling practices.  Quick background info: Both WGS84 (ITRF2014) and ETRS89 (ETRF2000) are going to be used for a project, which means when transforming data between the two CRS, custom transformation parameters need to be applied as per the corresponding epoch of the data acquisition/creation.  So I was wondering - which of the following ways is going to work (if none) and which one is the best way of doing it:  1. Applying the Custom Transformation to the datasets themselves with the help of the Project tool, while leaving standard transformation in Map Properties (ETRS 1989 to WGS 1984) or no transformation at all if Map already set in the correct Datum.  2. Applying standard transformation to the datasets (ETRS 1989 to WGS 1984) using the project tool and specifying the Custom Transformation in the Map Properties.  3. Applying custom transformation in both the dataset and in the Map Properties. From my current understanding the best practice is number 1, as the second will result to positioning slivers and shifts when more than one custom epoch is being used, while number 3 is like applying the custom transformation twice - which will result to errors.  Please let me if you agree with this assumption, or if there is something I am missing, and/or you would like to add something on that.  Thank you very much in advance and looking forward to your replies!  Best,  M.  ... View more

Esri and ICSM support direct transformations between GDA2020 and WGS84 ... View more

The US National Geodetic Survey (NGS) is implimenting a plan to replace NAD 83 and NAVD 88 through a modernization effort.   NGS’s main page on the subject: https://www.ngs.noaa.gov/datums/newdatums/index.shtml   NGS has been very proactive in publishing information on the planned changes, and has had several summits to directly communicate with stakeholders and invite feedback. This year’s is on May 6-7 in Silver Spring, Maryland. https://www.ngs.noaa.gov/geospatial-summit/index.shtml   Last year there was a special industry partner summit. We’ve had someone at all of these geospatial summits, and have met many of the NGS personnel who are involved in the effort.   We are also attending or watching the NGS webinars related to this subject to make sure that we’re on top of the situation.   NGS has stated that they will release beta versions of data, transformations, etc. ahead of the 2022 date. So far there hasn’t been anything that Esri can test. We plan to incorporate any new coordinate system definitions (geodetic, projected, and vertical) as they’re released officially. If NGS releases beta versions, we plan to check that we do not see any issues and that they can be used in the software.   We have occasionally pre-empted an official release of transformation grid files or coordinate systems because supposedly the names and other information have been finalized and put the objects into a current software release. Then the names are changed and we end up having to change/delete/add the existing definitions. Because there are a lot of customers using US data, we want to be very careful adding these new coordinate systems and transformations for the 2022 modernization. ... View more