CODEWITHSUNDEEP
javascriptopenlayersopenstreetmap
user3062040
user3062040

Reputation: 41

How to draw a line following the road in OpenLayers

On an OSM base layer, I have drawn a line following 3 points, with an array for the points and the object/method OpenLayers.Geometry.LineString

Now, I'd like this line to follow the road. Some hours spent on internet, and impossible to find a solution. Is there an object for this ? Do I have to catch some information from the tiles first ?

May I ask some help please ?

Here under is how I'm drawing the straight line

function init() {

    var epsg4326 = new OpenLayers.Projection("EPSG:4326");
    var map = new OpenLayers.Map('map');

    var osmLayer = new OpenLayers.Layer.OSM("OSM");
    map.addLayer(osmLayer);
    var center = new OpenLayers.LonLat(-71.6, -33.7).transform(epsg4326,map.getProjectionObject());
    map.setCenter(center,4); 

    var points = new Array(
        new OpenLayers.Geometry.Point(-71.26,-32.47),
        new OpenLayers.Geometry.Point(-71.30,-32.97),
        new OpenLayers.Geometry.Point(-70.81,-32.89)
    );

    var myLine = new OpenLayers.Geometry.LineString(points).transform(epsg4326, map.getProjectionObject());
    var myLineStyle = {strokeColor:"#0500bd", strokeWidth:3};
    var myFeature = new OpenLayers.Feature.Vector(myLine, {}, myLineStyle);
    var myVector = new OpenLayers.Layer.Vector("line test");
    myVector.addFeatures([myFeature]);
    map.addLayers([myVector]);

}

Upvotes: 4

Views: 4818

Answers (1)

scai
scai

Reputation: 21469

Usually OpenLayers just displays raster tiles but you can't extract road geometry information out of them. You need either raw or otherwise pre-processed data for this. Both OpenLayers and Leaflet are able to display GPX files. So once you got a GPX file everything else will become easy.

Unfortunately you didn't tell us whether you want to follow it a specific road (based on a name/address? or based on coordinates?) or whether you want to display a route along several roads or something completely different.

For retrieving raw geoinformation out of OpenStreetMap there is an official API, and there is the Overpass API which is usually a lot faster and allows to specify rather complex queries. But displaying such raw data requires a lot of preprocessing first.

If you want to display a route instead then you can choose one of the available online routers for OSM, for example OSRM. Many of them offer a GPX export of the calculated route which you can then use with OpenLayers.

There are a few more options but presenting them here without knowing what you are actually trying to do would be a waste of time.

Upvotes: 6

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