How to add a line on the map - Amazon Location Service
Adding a pre-recorded lineAdd a line in real-timeDeveloper tips

How to add a line on the map

With Amazon Location Service, you can add both pre-recorded GPS traces as line-strings and real-time GPS traces to dynamic maps.

Adding a pre-recorded line

In this example, you will add a pre-recorded GPS trace as a GeoJSON (main.js) to the dynamic map. To do so, you need to add a source (like GeoJSON) and a layer with line styling of your choice to the map.

index.html

    <!DOCTYPE html>
    <html lang="en">
        <head>
            <title>Add a line on the map</title>
            <meta property="og:description" content="Initialize a map in an HTML element with MapLibre GL JS." />
            <meta charset='utf-8'>
            <meta name="viewport" content="width=device-width, initial-scale=1">
            <link rel='stylesheet' href='https://unpkg.com/maplibre-gl@4.x/dist/maplibre-gl.css' />
            <link rel='stylesheet' href='style.css' />
            <script src='https://unpkg.com/maplibre-gl@4.x/dist/maplibre-gl.js'></script>
            <script src='main.js'></script>
        </head>
        <body>
            <!-- Map container -->
            <div id="map"></div>
            <script>
                const apiKey = "<API_KEY>";
                const mapStyle = "Standard";
                const awsRegion = "eu-central-1";
                const styleUrl = `https://maps.geo.${awsRegion}.amazonaws.com/v2/styles/${mapStyle}/descriptor?key=${apiKey}`;

                const map = new maplibregl.Map({
                    container: 'map',
                    style: styleUrl,
                    center: [-123.126575, 49.290585],
                    zoom: 12.5
                });

                map.on('load', () => {
                    map.addSource('vancouver-office-to-stanley-park-route', {
                        type: 'geojson',
                        data: routeGeoJSON
                    });

                    map.addLayer({
                        id: 'vancouver-office-to-stanley-park-route',
                        type: 'line',
                        source: 'vancouver-office-to-stanley-park-route',
                        layout: {
                            'line-cap': 'round',
                            'line-join': 'round'
                        },
                        paint: {
                            'line-color': '#008296',
                            'line-width': 2
                        }
                    });
                });
            </script>
        </body>
    </html>
style.css

    body { margin: 0; padding: 0; }
    html, body, #map { height: 100%; }
main.js

    const routeGeoJSON = {
        type: "FeatureCollection",
        features: [
            {
                type: "Feature",
                geometry: {
                    type: "LineString",
                    coordinates: [
                        [-123.117011, 49.281306],
                        [-123.11785, 49.28011],
                        ...
                        [-123.135735, 49.30106]
                    ]
                },
                properties: {
                    name: "Amazon YVR to Stanley Park",
                    description: "An evening walk from Amazon office to Stanley Park."
                }
            }
        ]
    };

Add a line in real-time

In this example, you will simulate adding new GPS coordinates one by one to create a real-time GPS trace. This is useful for tracking real-time data updates.

index.html

    <!DOCTYPE html>
    <html lang="en">
        <head>
            <title>Add a line on the map in real-time</title>
            <meta property="og:description" content="Initialize a map in an HTML element with MapLibre GL JS." />
            <meta charset='utf-8'>
            <meta name="viewport" content="width=device-width, initial-scale=1">
            <link rel='stylesheet' href='https://unpkg.com/maplibre-gl@4.x/dist/maplibre-gl.css' />
            <link rel='stylesheet' href='style.css' />
            <script src='https://unpkg.com/maplibre-gl@4.x/dist/maplibre-gl.js'></script>
            <script src='main.js'></script>
        </head>
        <body>
            <!-- Map container -->
            <div id="map"></div>
            <script>
                const apiKey = "<API_KEY>";
                const mapStyle = "Standard";
                const awsRegion = "eu-central-1";
                const styleUrl = `https://maps.geo.${awsRegion}.amazonaws.com/v2/styles/${mapStyle}/descriptor?key=${apiKey}`;

                const map = new maplibregl.Map({
                    container: 'map',
                    style: styleUrl,
                    center: [-123.126575, 49.290585],
                    zoom: 12.5
                });

                map.on('load', () => {
                    const coordinates = routeGeoJSON.features[0].geometry.coordinates;
                    routeGeoJSON.features[0].geometry.coordinates = [coordinates[0], coordinates[20]];

                    map.addSource('vancouver-office-to-stanley-park-route', {
                        type: 'geojson',
                        data: routeGeoJSON
                    });

                    map.addLayer({
                        id: 'vancouver-office-to-stanley-park-route',
                        type: 'line',
                        source: 'vancouver-office-to-stanley-park-route',
                        layout: {
                            'line-cap': 'round',
                            'line-join': 'round'
                        },
                        paint: {
                            'line-color': '#008296',
                            'line-width': 2
                        }
                    });

                    map.jumpTo({center: coordinates[0], zoom: 14});
                    map.setPitch(30);

                    let i = 0;
                    const timer = window.setInterval(() => {
                        if (i < coordinates.length) {
                            routeGeoJSON.features[0].geometry.coordinates.push(coordinates[i]);
                            map.getSource('vancouver-office-to-stanley-park-route').setData(routeGeoJSON);
                            map.panTo(coordinates[i]);
                            i++;
                        } else {
                            window.clearInterval(timer);
                        }
                    }, 100);
                });
            </script>
        </body>
    </html>
style.css

    body { margin: 0; padding: 0; }
    html, body, #map { height: 100%; }
main.js

    const routeGeoJSON = {
        type: "FeatureCollection",
        features: [
            {
                type: "Feature",
                geometry: {
                    type: "LineString",
                    coordinates: [
                        [-123.117011, 49.281306],
                        [-123.11785, 49.28011],
                        ...
                        [-123.135735, 49.30106]
                    ]
                },
                properties: {
                    name: "Amazon YVR to Stanley Park",
                    description: "An evening walk from Amazon office to Stanley Park."
                }
            }
        ]
    };

Developer tips

Fitting bounds: You can fit the line to the map bounds by calculating the bounds of the line's coordinates:


    const coordinates = routeGeoJSON.features[0].geometry.coordinates;
    const bounds = coordinates.reduce((bounds, coord) => bounds.extend(coord), new maplibregl.LngLatBounds(coordinates[0], coordinates[0]));
    map.fitBounds(bounds, { padding: 20 });