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Using the Visual
This page summarises the key capabilities of the OS Power BI Map Visual. For full step-by-step instructions, refer to the OS Maps for Power BI Visual documentation on the OS docs site.
The visual is distributed as a .pbiviz file. Download the latest version from the Releases page, then import it into Power BI via Insert → Visuals → Import a visual from a file.
Your Power BI administrator must have enabled the use of custom visuals from files for this to work.
→ Full installation instructions
- Power BI Desktop or Power BI Service (web). Tested against Power BI Desktop version 2.142.1277.0 64-bit (April 2025) or later; older versions are not guaranteed to work.
- An OS Maps API key from the OS Data Hub. This is required to display the basemap — enter it in the visual's settings pane.
- An internet connection — the visual does not work offline. Map tiles, geocoding lookups, and ONS boundary retrieval all require network access.
The visual renders OS basemap tiles using the OS Maps API. Available map styles include OS Road, OS Light, OS Outdoor, and OS Leisure. The basemap can be displayed in either WGS84 (EPSG:4326) or British National Grid (EPSG:27700) projection.
Data is added by dragging Power BI table fields into the visual's field wells. The visual supports two independent data layers which can be used separately or together:
- Features layer — typically polygon/area data (choropleth maps, or custom geometries)
- Points layer — point data plotted as circle markers
→ Adding data to the map → Using both map layers together
The visual supports drag-and-drop geocoding for several location identifier types. Drag the relevant column into the appropriate field well and the visual will resolve locations automatically:
| Location type | Field well | Notes |
|---|---|---|
| Latitude / Longitude | Lat + Lon fields | Passed through directly |
| Easting / Northing | Easting + Northing fields | Converted via OSTN15 grid |
| Postcode | Postcode field | Resolved via Codepoint Open (AGOL-hosted) |
| UPRN | UPRN field | Resolved via OpenUPRN (AGOL-hosted) |
| GSS code | GSS Code field | Boundary retrieved from ONS services (AGOL-hosted) |
Only open-data sources are used for geocoding. No per-user authentication is required beyond the OS Maps API key. Up to 30,000 features can be geocoded in a single visual instance.
GSS (Government Statistical Service) codes in the GSS Code field well automatically retrieve the corresponding ONS boundary polygon. This gives access to hundreds of boundary types — LSOAs, MSOAs, wards, local authority districts, parliamentary constituencies, and many more — without importing any geometry files into your Power BI data model.
→ How to add a polygon reference layer to the map
Polygon or point geometries held in a Power BI data model as WKT or GeoJSON strings can be added to the features layer. Note Power BI's 30 KB field length limit applies; power users can work around this by concatenating multiple fields within a Power BI query.
→ Displaying your own geometries
Features are coloured by a data field dragged into the Colour field well:
- Continuous values — a colour ramp between two user-chosen endpoint colours, with min–max or percent-clip stretch available.
- Categorical values — either pre-determined ColorBrewer palettes (up to 12 classes, recommended) or user-controlled endpoint colours.
Point size on the points layer can be set to a fixed value or driven by a data field.
See Design Philosophy for the reasoning behind these symbology choices.
The visual participates in Power BI's cross-filtering. To select features and cross-filter other visuals in the report:
- Activate the lasso tool from the visual's toolbar.
- Draw a selection area around the features you wish to select.
- Selected features are passed to Power BI, which updates all other cross-filterable visuals in the report.
Selection is limited to 500 features at once for performance reasons. To clear a selection, use the reset button in the toolbar.
A reference boundary layer can be displayed by entering a list of GSS codes into the Reference Layer Identifiers settings field. These boundaries are retrieved and shown on the map with a neutral background symbology, making it clear they are not part of the main data.
The reference layer automatically suppresses any feature that is currently shown in the main data layer to avoid duplication. This is useful for displaying a full set of boundaries (e.g. all wards in a local authority) as geographic context while the data layer shows only a cross-filtered subset.
Clicking on a feature opens a popup showing its attribute values. Where multiple features overlap at the clicked location (e.g. coincident points, or points overlapping polygons), the popup is paginated to allow navigation between all features at that location.
Common questions about the visual are answered in the OS Maps for Power BI Visual FAQs on the OS docs site, covering topics including:
- Whether the visual is free to use
- Limits on numbers of points/polygons and layers
- What a GSS identifier is, and which boundaries are supported
- Northern Ireland coverage
- Data storage and external services used