[GIS] openlayers extent intersects is not working properly

extentsintersectopenlayers

I am using

ol.extent.intersects(extent1, extent2)

to check for intersection between layers and polygon I drew, but it doesn't get me any intersection which is weird because I draw the polygon creating intersection with the layer

can you think of any reason of this please ?

Best Answer

The reason was that the projection of the vector and the projection of the polygons drawn are different. To check for intersection, the projection for the vector and the polygons should be the same.

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[GIS] How to draw a polygon in OpenLayers 3

This code is working correctly. where vertices are the array of coordinates

var feature = new ol.Feature({
            geometry: new ol.geom.Polygon([vertices])
        });

feature.getGeometry().transform('EPSG:4326', 'EPSG:3857');
var vectorSource= new ol.source.Vector({
        features: [feature ]
    });

 var vectorLayer = new ol.layer.Vector({
        source: vectorSource
    });
 var map = new ol.Map({
        target: $('#map')[0],
        layers: [
            new ol.layer.Tile({
                source: new ol.source.TileJSON({
                    url: 'http://api.tiles.mapbox.com/v3/mapbox.geography-class.jsonp'
                })
            }),
            vectorLayer 
        ],
        view: new ol.View({
            center: ol.proj.transform([104.07143559628913, 30.669867138240782], 'EPSG:4326', 'EPSG:3857'),
            zoom: 12
        })
    });

Demo

[GIS] OpenLayers 3 Zoom to extent only working in debug

I had a similar problem in version 3.8.2. I solved it by putting getExtent into the event:

vector.getSource().on("change", function(evt) {
    extent = vector.getSource().getExtent();
    map.getView().fit(extent, map.getSize());
});

In older version you just use fitExtent instead of fit.

Best Answer

Related Solutions

[GIS] How to draw a polygon in OpenLayers 3

[GIS] OpenLayers 3 Zoom to extent only working in debug

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