Set up a new connection

Once a new project with a base map map has been set up, zoom in to a small area to reduce the number of requests that are initially sent to the API. Select Layer > Add Layer > Add WFS / OGC API - Features Layer.

Create a new connection

In the Data Source Manager | WFS / OGC API - Features dialog click New and in the New WFS Connection dialog:

• Name: Provide a name for the connection. You can reuse this connection in the future.

• URL: Copy the OS NGD API – Features endpoint address from the OS Data Hub and paste it into this field. Your API Key is automatically appended to this URL in the key parameter.

• Authentication: Leave these settings at their defaults. You do not need a username or password as authentication is done through your API Key.

• Version: Click Detect to identify the version.

• Enable feature paging: Select this option, if necessary.

• Page size: Enter a maximum page size. This limits the page size to a maximum number of features. We recommend a setting of about 100 to speed up response times. Larger values may result in a very slow response time.

• Other: Leave the other settings at their defaults.

• Click OK.

Adding layers to the map

Data Source Manager | WFS / OGC API - Features dialog:

• Select your new connection in the dropdown, if necessary.

• Click Connect.

When you click Connect, a list of layers available in OS NGD API – Features populates in the main box:

• To add a layer to the map: Select the layer to highlight it. You can select multiple layers by using the Ctrl key.

• Only request features overlapping the view extent: Select this option.

• Click Add.

The layer will then display in the Layers panel and the data will display on the map:

Set up a connection

Once a new project with a new map has been set up, select Insert > Connections > Server > New OGC API Server.

Add an API URL and set up custom parameters

In the Add OGC API Server Connection dialog:

• Server URL: Enter the URL for OS NGD API – Features, excluding the API Key. For example, https://api.os.uk/features/ngd/ofa/v1.

• Select Custom request parameters and enter the following:

  • Parameter: key

  • Value: [Insert your OS API Key here]

• Click OK.

Adding layers to the map

You can explore the available layers in OS NGD API – Features by using the ArcGIS Pro Catalog panel.

In the Catalog panel:

• To add a layer to the map: Right-click on a layer and select Add to Current Map.

In the pop-up Add OGC API Layer(s) dialog:

• Set the maximum features returned: Set the maximum number of features to be displayed (we suggest 1000).

• To specify the extent:

  • Select the Use Spatial Extent checkbox.

  • Get extent from: Select Current visible extent.

  • Click OK to load the features onto the map.

The layer will then display in the Contents panel and the data will display on the map:

Adjusting the map view

Features will not automatically refresh when you zoom or pan on the map. This is purposely designed to protect the API from unnecessary spikes in usage.

If the extent of the screen changes and you need to update the features displayed, right-click on the layer in the Contents panel, then select the OGC Features property for the layer, re-click Current visible extent, and click Apply and OK. This will force ESRI ArcGIS Pro to send a new request to the API and load features based on the new extent.

Add a new layer

Once you've signed into your ESRI ArcGIS Online account and opened the map viewer. Zoom in to a small area to reduce the number of requests that are initially sent to the API.

• Select Layers > Add > Add layer from URL.

Add an API and set up custom parameters

In the Add Layer dialog:

• URL: Enter the base URL for OS NGD API – Features, excluding the API Key. For example, https://api.os.uk/features/ngd/ofa/v1.

• Type: Select OGC feature layer.

• Select Custom request parameters and enter the following:

  • Parameter: key

  • Value: [Insert your OS API Key here]

• Click Next.

Adding layers to the map

In the Add Layer dialog:

• To add a layer to the map: Select a layer to add to the map and then click Add to map.

The layer will then display in the Layers panel and the data will display on the map:

Features will automatically refresh when you zoom or pan on the map. If you wish to add multiple layers to the same map, repeat steps 2 and 3.

Add overlay

Once a new map has been set up, in the Home tab, click Add Overlay.

Select API

In the Overlay Types dialog:

• Select Ordnance Survey (GB) > OS (GB) Data Hub, and then click Next.

In the OS (GB) Data Hub dialog:

• Select OS National Geographic Database (NGD) API – Features.

• API Key: Enter your API key.

• Premium/Public Sector Plan: Select this option if you have this plan.

• Save in the UI settings database (encrypted): Select this option.

• Click Next.

Adding layers to the map

In the OS Data Hub NGD API – Features Data Themes and Feature Types dialog:

• Well-known ‘recipe’: Select a predefined recipe, if available.

• Data Themes: Select your data themes.

• Features: If necessary, use the editing tools (on the right) to delete feature types or to change the order in which they display in your SIS Workspace Definition (SWD). By default, all feature types within the selected data themes are available in the right panel.

• Local cache: Select this option to store the data temporarily on your machine. If you save and reopen the SWD, the data will still be available as it is fetched from your local cache.

• One-off import: Select this option to do a one-off import of the data. If you save and reopen the SWD, the data will not be available and you will need to re-import it. These imports have a larger file size.

• Filtering: These settings are used in conjunction and define how much data is required for display. It is recommended that you always set a spatial filter and feature limit.

  • Spatial: The Intersect with current view extent option limits the download to only selected features within the current window extent. You can also load features within a specific area of interest using the polygon feature to draw your area of interest on the map BEFORE opening the Add Overlay dialog.

  • Maximum number of features: Limits the number of feature values downloaded to the number set. This limit is applied per feature within any filtered spatial area.

• Click Finish.

The selected layer(s) will then display in the SIS Workspace Definition (SWD) and the data will display in the map area:

Set up your HTML file

• Create a new HTML file with a text editor (for example, Notepad, Visual Studio Code).

• Add the basic HTML structure to your file with a placeholder <div> for the map.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>OS NGD API – Features | Template (EPSG:3857) | OpenLayers</title>
    
    <!--Add the Ordnance Survey Styling-->
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/OrdnanceSurvey/os-api-branding@0.3.1/os-api-branding.css" />
    <script src="https://cdn.jsdelivr.net/gh/OrdnanceSurvey/os-api-branding@0.3.1/os-api-branding.js"></script>
    
    <!--Add the OpenLayers libraries-->
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/ol@v8.1.0/ol.css" />
    <script src="https://cdn.jsdelivr.net/npm/ol@v8.1.0/dist/ol.js"></script>
    
    <style>
        /* Set the map container size and style */
        body { margin: 0; padding: 0; }
        #map { position: absolute; top: 0; bottom: 0; width: 100%; }
    </style>
</head>
<body>
    
    <!--Create a div element to hold the map-->
    <div id="map"></div>
    
    <!--Add your Javascript code below--> 
    <script>
        // Your Javascript code will go here

    </script>

</body>
</html>

Insert your API Key and OS NGD collection

• To enable access to OS APIs an API Key is required. Inside the <script> tag, add a variable called apiKey, replacing 'INSERT_API_KEY_HERE' with the API Key from your project.

• Add a variable called collectionId, replacing 'INSERT_COLLECTIONID_HERE' with the collection ID for the desired OS NGD feature type and version (for example, bld-fts-buildingpart-1).

// Set API Key 
 const apiKey = 'INSERT_API_KEY_HERE';
 
 const collectionId= 'INSERT_COLLECTIONID_HERE';

Add a basemap

• Create a source for the basemap layer using OS Maps API and initialise the ol.map class with the applicable map properties – target, layers and view. Add the following code inside the JavaScript block:

// Initialize the map object.
    const map = new ol.Map({
        target: 'map',
        layers: [
            new ol.layer.Tile({
                source: new ol.source.XYZ({
                    url: `https://api.os.uk/maps/raster/v1/zxy/Light_3857/{z}/{x}/{y}.png?key=${apiKey}`
                })
            })
        ],
        view: new ol.View({
            projection: 'EPSG:3857',
            extent: ol.proj.transformExtent([ -10.76418, 49.528423, 1.9134116, 61.331151 ], 'EPSG:4326', 'EPSG:3857'),
            minZoom: 7,
            maxZoom: 20,
            center: ol.proj.fromLonLat([ -3.541809, 50.727589 ]),
            zoom: 18
        })
    });

The above code creates the main map instance using the OpenLayers library where you can specify various properties:

• target: Defines where the map should be displayed. In this instance, it is set to the id of the <div> element.

• layers: An array containing the layers to be added to the map.

• view: Defines the initial view of the main, containing various settings such as projection, extent (the geographic bounds of the map), minimum and maximum zoom levels, centre of the map and the initial zoom level.

Add an OS NGD API – Features layer

• Define and initialise the source using the ol.source.Vector class to make a request to OS NGD API – Features. By utilising the ol.loadingstrategy.bbox this means that data from OS NGD API – Features will be loaded based on the visible map extent.

• To create a separate layer to overlay OS NGD data onto the map, you will need to add the ngdFeatures layers to the ol.map object to render both layers on the map.

// Create the NGD Features API layer (with BBOX strategy).
    const ngdFeatures = new ol.layer.Vector({
        source: new ol.source.Vector({
            format: new ol.format.GeoJSON(),
            url: function(extent) {
                return (
                    `https://api.os.uk/features/ngd/ofa/v1/collections/${collectionId}/items?key=${apiKey}&bbox=${extent.join(',')}&bbox-crs=http://www.opengis.net/def/crs/EPSG/0/3857`
                );
            },
            strategy: ol.loadingstrategy.bbox
        })
    });

    // Add the NGD Features API layer to the map.
    map.addLayer(ngdFeatures);

Set up your HTML file

• Create a new HTML file with a text editor (for example, Notepad, Visual Studio Code).

• Add the basic HTML structure to your file with a placeholder <div> for the map.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>OS NGD API – Features | Template (EPSG:3857) | Maplibre GL JS</title>
    
    <!--Add the Ordnance Survey Styling-->
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/OrdnanceSurvey/os-api-branding@0.3.1/os-api-branding.css" />
    <script src="https://cdn.jsdelivr.net/gh/OrdnanceSurvey/os-api-branding@0.3.1/os-api-branding.js"></script>
    
    <!--Add the Maplibre GL JSlibraries-->
    <link rel="stylesheet" href="https://unpkg.com/maplibre-gl@2.4.0/dist/maplibre-gl.css" />
    <script src="https://unpkg.com/maplibre-gl@2.4.0/dist/maplibre-gl.js"></script>
   
    <style>
        /* Set the map container size and style */
        body { margin: 0; padding: 0; }
        #map { position: absolute; top: 0; bottom: 0; width: 100%; }
    </style>
</head>
<body>
    
    <!--Create a div element to hold the map-->
    <div id="map"></div>
    
    <!--Add your Javascript code below--> 
    <script>
        // Your Javascript code will go here

    </script>

</body>
</html>

Insert your API Key and OS NGD collection

• To enable access to OS APIs an API Key is required. Inside the <script> tag, add a variable called apiKey, replacing 'INSERT_API_KEY_HERE' with the API Key from your project.

• Add a variable called collectionId, replacing 'INSERT_COLLECTIONID_HERE' with the collection ID for the desired OS NGD feature type and version (for example, bld-fts-buildingpart-1).

// Set API Key 
 const apiKey = 'INSERT_API_KEY_HERE';
 
 const collectionId= 'INSERT_COLLECTIONID_HERE';

Add a basemap

• To add the OS Maps API, you will need to define the map style using MapLibre GL JS's format. This specifies the source of map tiles, which will be retrieved from OS Maps API in the 'Light' raster tiles style.

• Initialise the map object using the maplibregl.Map class to configure the basemap layer and define its properties – container, minZoom, maxZoom, maxBounds, style, center and zoom.

• Add navigation controls to the map, excluding the compass button and disabling map rotation.

// Create a map style object using the ZXY service.
    const style = {
    "version": 8,
        "sources": {
            "raster-tiles": {
            "type": "raster",
            "tiles": [`https://api.os.uk/maps/raster/v1/zxy/Light_3857/{z}/{x}/{y}.png?key=${apiKey}`],
            "tileSize": 256
            }
         },
         "layers": [{
             "id": "os-maps-zxy",
             "type": "raster",
             "source": "raster-tiles"
         }]
     };
     
     // Initialize the map object.
         const map = new maplibregl.Map({
             container: 'map',
             minZoom: 6,
             maxZoom: 19,
             style: style,
             maxBounds: [
                 [-10.76418, 49.528423],
                 [1.9134116, 61.331151]
             ],
             center: [-3.541809, 50.727589],
             zoom: 17
         });
         
         map.dragRotate.disable(); // Disable map rotation using right click + drag.
         map.touchZoomRotate.disableRotation(); // Disable map rotation using touch rotation gesture.
         
         // Add navigation control (excluding compass button) to the map.
         map.addControl(new maplibregl.NavigationControl({
             showCompass: false
             }));

The above code creates the main map instance using the MapLibre GL JS library where you can specify various properties:

• container: Defines where the map should be displayed. In this instance, it is set to the id of the <div> element.

• minZoom and maxZoom: Sets the minimum and maximum zoom level for the map. Users will not be able to go beyond these levels.

• maxBounds: Defines the maximum bounds and restricts panning the map.

• style: Defines the style of the map, configured via a URL pointing at the style specified.

• center: Sets the initial centre point of the map.

• zoom: Sets the initial zoom level of the map.

Add an OS NGD API – Features layer

• Create an empty GeoJSON placeholder to hold the feature objects called by OS NGD API – Features.

• Create a function called fetchFeatures that fetches the API based on the current map extent (bounding box) by generating a bbox string.

• Construct the API request URL to fetch OS NGD data from OS NGD API – Features. The URL includes the collectionId, bbox and apiKey.

• Once the features have been returned in JSON, update the source data of the map's layers to display the features.

let layers = [ 'polygon', 'linestring', 'point' ];

// Create an empty GeoJSON FeatureCollection.
const geoJson = {
    "type": "FeatureCollection",
    "features": []
};

// Define an asynchronous function to fetch and display the NGD Features API features.
async function fetchFeatures(bounds) {
        // Generate a BBOX string for the map extent.
        const bbox = bounds.toArray().toString();

        // Construct the NGD Features API request URL.
        const url = `https://api.os.uk/features/ngd/ofa/v1/collections/${collectionId}/items?&key=${apiKey}&bbox=${bbox}`;

        // Fetch features from the API endpoint.
        const features = await fetch(url).then(response => response.json());

        // Update the source data with the new GeoJSON data.
        layers.forEach((element) => map.getSource(element).setData(features))
}

Load and update features on the map dynamically

• Event listeners are triggered when the map loads and finishes moving (panning or zooming) to load and update features based on the map's updated extent. Inside the map.on('load',...) event handler, we add styles for various types of features, including polygons, linestrings and points so that any collectionId specified will render.

The map.on('moveend',...) event handler will then fetch and update the features based on the map's current extent.

map.on('load', () => {
    // Add a fill style layer to render polygons on the map.
    map.addLayer({
        "id": "polygon",
        "type": "fill",
        "source": {
            "type": "geojson",
            "data": geoJson
        },
        "layout": {},
        "paint": {
            "fill-color": "rgba(51,136,255,0.3)",
            "fill-outline-color": "#38f"
        },
        "filter": [ "==", "$type", "Polygon" ]
    });

    // Add a line style layer to render linestrings on the map.
    map.addLayer({
        "id": "linestring",
        "type": "line",
        "source": {
            "type": "geojson",
            "data": geoJson
        },
        "layout": {},
        "paint": {
            "line-color": "#38f",
            "line-width": 1
        },
        "filter": [ "==", "$type", "LineString" ]
    });

    // Add a circle style layer to render points on the map.
    map.addLayer({
        "id": "point",
        "type": "circle",
        "source": {
            "type": "geojson",
            "data": geoJson
        },
        "layout": {},
        "paint": {
            "circle-color": "rgba(51,136,255,0.8)",
            "circle-radius": 4,
            "circle-stroke-color": "#fff",
            "circle-stroke-width": 1
        },
        "filter": ["==", "$type", "Point"]
    });

    // Get the visible map bounds (BBOX).
    let bounds = map.getBounds();

    // Initial fetch and display of features.
    fetchFeatures(bounds);
        
    // Add event which will be triggered when the map has finshed moving (pan + zoom).
    // Implements a simple strategy to only request data when the map viewport invalidates
    // certain bounds.
    map.on('moveend', function() {
        let bounds1 = new maplibregl.LngLatBounds(bounds.getSouthWest(), bounds.getNorthEast()),
            bounds2 = map.getBounds();

        if( JSON.stringify(bounds) !== JSON.stringify(bounds1.extend(bounds2)) ) {
            bounds = bounds2;
            fetchFeatures(bounds);
        }
    });
});

Set up your HTML file

• Create a new HTML file with a text editor (for example, Notepad, Visual Studio Code).

• Add the basic HTML structure to your file with a placeholder <div> for the map.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>OS NGD API – Features | Template (EPSG:3857) | Leaflet</title>
    
    <!--Add the Ordnance Survey Styling-->
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/OrdnanceSurvey/os-api-branding@0.3.1/os-api-branding.css" />
    <script src="https://cdn.jsdelivr.net/gh/OrdnanceSurvey/os-api-branding@0.3.1/os-api-branding.js"></script>
    
    <!--Add the Leaflet libraries-->
    <link rel="stylesheet" href="https://unpkg.com/leaflet@1.9.4/dist/leaflet.css" />
    <script src="https://unpkg.com/leaflet@1.9.4/dist/leaflet.js"></script>
    
   
    <style>
        /* Set the map container size and style */
        body { margin: 0; padding: 0; }
        #map { position: absolute; top: 0; bottom: 0; width: 100%; }
    </style>
</head>
<body>
    
    <!--Create a div element to hold the map-->
    <div id="map"></div>
    
    <!--Add your Javascript code below--> 
    <script>
        // Your Javascript code will go here

    </script>

</body>
</html>

Insert your API Key and OS NGD collection

• To enable access to OS APIs an API Key is required. Inside the <script> tag, add a variable called apiKey, replacing 'INSERT_API_KEY_HERE' with the API Key from your project.

• Add a variable called collectionID, replacing 'INSERT_COLLECTIONID_HERE' with the collection ID for the desired OS NGD feature type and version (for example, bld-fts-buildingpart-1).

// Set API Key 
 const apiKey = 'INSERT_API_KEY_HERE';
 
 const collectionId= 'INSERT_COLLECTIONID_HERE';

Add a basemap

• Define the configuration options for the map, defining minZoom, maxZoom, center, zoom, maxBounds, attributionControl.

  • minZoom and maxZoom: Sets the minimum and maximum zoom level for the map. Users will not be able to go beyond these levels.

  • center: Sets the initial centre point of the map.

  • zoom: Sets the initial zoom level of the map.

  • maxBounds: Defines the maximum bounds and restricts panning the map.

  • style: Defines the style of the map, configured via a URL pointing at the style specified.

  • attributionControl: When set to 'false', it hides the attribution control which displays map credits.

• Initialize the map with the id of the <div> element and the configuration option defined in mapOptions.

• Using the 'L.tileLayer' method, specify the basemap layer for OS Maps API, which includes your API Key to load the tiles to your map.

// Initialize the map.
    const mapOptions = {
        minZoom: 7,
        maxZoom: 20,
        center: [ 50.727589, -3.541809 ],
        zoom: 18,
        maxBounds: [
            [ 49.528423, -10.76418 ],
            [ 61.331151, 1.9134116 ]
        ],
        attributionControl: false
    };

    const map = L.map('map', mapOptions);

    // Load and display ZXY tile layer on the map.
    const basemap = L.tileLayer(`https://api.os.uk/maps/raster/v1/zxy/Light_3857/{z}/{x}/{y}.png?key=${apiKey}`, {
        maxZoom: 20
    }).addTo(map);

Add an OS NGD API – Features layer

• Create a function called fetchFeatures that fetches the API based on the current map extent (bounding box) by generating a bbox string.

• Construct the API request URL to fetch OS NGD data from OS NGD API – Features. The URL includes the collectionId, bbox and apiKey.

• Once the features have been returned in JSON, update the source data of the map's layers to display the features.

// Add layer group to make it easier to add or remove layers from the map.
    const lyrGroup = new L.layerGroup().addTo(map);

// Define an asynchronous function to fetch and display the NGD Features API features.
    async function fetchFeatures(bounds) {
        // Generate a BBOX string for the map extent.
        const bbox = bounds.toBBoxString();

        // Construct the NGD Features API request URL.
        const url = `https://api.os.uk/features/ngd/ofa/v1/collections/${collectionId}/items?key=${apiKey}&bbox=${bbox}`;

        // Fetch features from the API endpoint.
        const features = await fetch(url).then(response => response.json());

        // Parse the GeoJSON data and display it on the map.
        lyrGroup.clearLayers().addLayer(L.geoJSON(features));
    }

// Get the visible map bounds (BBOX).
    let bounds = map.getBounds();

// Initial fetch and display of features.
    fetchFeatures(bounds);

Load and update features on the map dynamically

The map.on('moveend',...) event handler fetches and updates the features based on the map's current extent.

// Add event which will be triggered when the map has finshed moving (pan + zoom).
// Implements a simple strategy to only request data when the map viewport invalidates
// certain bounds.
    map.on('moveend', function() {
        let bounds1 = new L.latLngBounds(bounds.getSouthWest(), bounds.getNorthEast()),
            bounds2 = map.getBounds();

        if( JSON.stringify(bounds) !== JSON.stringify(bounds1.extend(bounds2)) ) {
            bounds = bounds2;
            fetchFeatures(bounds);
        }
    });

Plot Data

# Plot the features
gdf.plot(figsize=(12,8),facecolor="#2d8fb6", edgecolor="#b19d3e", lw=0.05)