As a regular user of ArcGIS Online and Experience Builder, I often work with spatial data in different coordinate reference systems – especially WGS84 (EPSG:4326) and national systems such as S-JTSK (EPSG:5514).
Currently, the coordinate system of a Web Map is implicitly set when the map is first created (based on the basemap or first operational layer). After that, there is no user-friendly way to view or change the map’s CRS, which causes multiple challenges:
Problems:
- The CRS is invisible in the Map Viewer interface – users cannot easily determine what coordinate system is being used.
- Even if the basemap is later replaced with one in WGS84, the Web Map may still retain a custom projection (e.g., S-JTSK), causing:
- Skewed rendering,
- Slow drawing performance (due to reprojection),
- Poor compatibility with other apps like Experience Builder.
- Editing the CRS requires manual modification of JSON via ArcGIS Assistant – a risky and non-intuitive process.
- ArcGIS Pro allows changing the map’s projection locally, but this does not propagate back to the original Web Map in AGOL.
Proposed improvements:
- Show the current CRS in the Map Viewer (Classic and new).
- Allow users to change the spatial reference of existing Web Maps, e.g.:
- Through map settings,
- By reinitializing based on a new basemap or user selection.
- Warn users when projections between layers and the map differ, and offer to reproject or recreate map in another CRS.
- Make this functionality available both in ArcGIS Online and ArcGIS Pro publishing workflows.
- If limitations apply, provide clear guidance or suggestions via the UI (e.g., when mixing projections).
Why this matters:
- It would prevent common confusion and wasted hours trying to “fix” reprojection artifacts.
- It would empower users to optimize performance and ensure accurate spatial display.
- It aligns with how GIS professionals work in ArcGIS Pro, where CRS control is standard.
- It reduces reliance on advanced JSON editing, which not all users are comfortable with.
