@GordonSumerling
The Esri Tech blog on GDA2020 https://esriaustraliatechblog.wordpress.com/2018/12/24/understanding-gda2020-and-its-relationship-with-web-gis/ recommends>
- Transform all data to GDA2020 and republish to Web GIS in GDA2020 or a GDA2020-based projected coordinate system.
- When publishing to WGS84, utilise the projection path GDA2020⇒GDA94⇒ Data will be published with GDA94 accuracy and coordinate transformations between WGS84 and GDA94 can be Performed.
- Create your own basemaps (Imagery, Street and Topographic) in GDA2020
- DO NOT mix data from GDA94 and GDA2020 in Web GIS as there will be a 1.8 metre alignment error regardless
- If coordinate conversion is required in Web GIS from WGS84 to GDA2020 then a transformation path of WGS84⇒GDA94⇒GDA2020 should be utilised
On point 3. Create your own basemaps in GDA2020 - has anybody done this and also successfully published as a WMTS? Is this even possible as default cache method is WGS84? Is this recommendation implying using the method GDA2020>WGS84 using null projection (EPSG:8450). As a side note customers using Geocortex require services to be published in the same datum as their basemap datums so the getcaps would need to specify GDA2020.
P.S a dedicated GDA2020 section in communities would be great 🙂 Kylie