Tip: Best with WMS, WFS, Esri ImageServer.
Although QGIS supports Esri MapServer format the composite or "double hop" transformation path required is not supported (information current at publication).
Generally avoid Esri MapServer if mixing with GDA2020 data unless your basemap projection is GDA94. Software needs to support the transformation path WGS84>GDA94>GDA2020.
Image showing QGIS and MapServer data misalignment
Transformations
Info: QGIS install comes with GDA94 to GDA2020 EPSG:8048 conformal transformation by default. The main transformation for WA, EPSG:8447 needs to be downloaded and installed. Newer versions of QGIS provide detailed transformation information and the required download link.
Screen shot from QGIS 3.16
WMS
QGIS Before and After: GDA2020 basemap (blue line) with GDA94 imagery and WMS Cadastre Address
Tip: After changing the layer CRS switching back to the original CRS will result in the layer disappearing from the map. If this happens, change CRS back to EPSG:4283 or remove the layer and re-add.
Tip: For data outside of the national grid use conformal only transformations - EPSG:8048 (7P), 8444 (Christmas Island) 8445 (Cocos (Keeling)).
- Starting with a basemap CRS of GDA2020
- From the Data Source Manager connect to the SLIP WMS service and add the layer. Do not change CRS at this point.
- In Project Properties >Transformations (CRS in older versions) add Datum Transformation GDA94 to GDA2020 (2) - EPSG:8447
- In the Layer Panel right-click the WMS layer and set Layer CRS to EPSG:4283
WFS
- Starting with a basemap CRS of GDA2020
- From the Data Source Manager connect to the SLIP WFS service using WFS Version 1.0
- Add the layer and do not change the CRS at this point.
- In Project Properties >Transformations add Datum Transformation GDA94 to GDA2020 (2) - EPSG:8447
- In the Layer Panel right-click the WMS layer and set Layer CRS to EPSG:4283