Reputation: 25
I have a jsfiddle below where I attempt to create a circle 1600 meters in radius. I don't think that I have the projection right, because this circle is definitely smaller than 1600 meters. Measuring on Google Maps I think it's around 1000 meters instead. What do I need to do to correct this please>
Thank you.
var centerLongitudeLatitude = ol.proj.fromLonLat([-1.733014, 51.982989]);
var layer = new ol.layer.Vector({
source: new ol.source.Vector({
projection: 'EPSG:4326',
features: [new ol.Feature(new ol.geom.Circle(centerLongitudeLatitude, 1600))]
}),
style: [
new ol.style.Style({
stroke: new ol.style.Stroke({
color: 'blue',
width: 3
}),
fill: new ol.style.Fill({
color: 'rgba(0, 0, 255, 0.1)'
})
})
]
});
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
source: new ol.source.OSM()
}),
layer
],
view: new ol.View({
center: ol.proj.fromLonLat([-1.733014, 51.982989]),
zoom: 14
})
});
html,
body {
height: 100%;
width: 100%;
padding: 0px;
margin: 0px;
}
.map {
height: 100%;
width: 100%;
}
<link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/openlayers/openlayers.github.io@master/en/v6.2.1/css/ol.css">
<script src="https://cdn.jsdelivr.net/gh/openlayers/openlayers.github.io@master/en/v6.2.1/build/ol.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="map" class="map"></div>
Upvotes: 0
Views: 1397
Reputation: 25
Thanks to Mike and cabesuon I have a solution, posted here for future readers.
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
source: new ol.source.OSM()
})
],
view: new ol.View({
center: ol.proj.fromLonLat([-1.733014, 51.982989]),
zoom: 14
})
});
var centerLongitudeLatitude = ol.proj.fromLonLat([-1.733014, 51.982989]);
var viewProjection = map.getView().getProjection();
var pointResolution = ol.proj.getPointResolution(viewProjection , 1, centerLongitudeLatitude );
var radius = 1600 / pointResolution;
var layer = new ol.layer.Vector({
source: new ol.source.Vector({
projection: 'EPSG:4326',
features: [new ol.Feature(new ol.geom.Circle(centerLongitudeLatitude, radius))]
}),
style: [
new ol.style.Style({
stroke: new ol.style.Stroke({
color: 'blue',
width: 3
}),
fill: new ol.style.Fill({
color: 'rgba(0, 0, 255, 0.1)'
})
})
]
});
map.addLayer(layer);
html,
body {
height: 100%;
width: 100%;
padding: 0px;
margin: 0px;
}
.map {
height: 100%;
width: 100%;
}
<link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/openlayers/openlayers.github.io@master/en/v6.2.1/css/ol.css">
<script src="https://cdn.jsdelivr.net/gh/openlayers/openlayers.github.io@master/en/v6.2.1/build/ol.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="map" class="map"></div>
Upvotes: 1
Reputation: 5268
You have an inconsistency between the SRS of the vector layer (EPSG:4326
), and the center and of the circle (EPSG:3857
). You need to one of the above, not both.
Try to create the layer without specifying projection
, it would use the default view projection, in this case EPSG:3857
(because of OSM).
UPDATE:
After building the snippet below, I realize that the proposed change does not affect the result, not sure why just now, so I proposed the use of Polygon.circular
as an alternative.
<!doctype html>
<html lang="en">
<head>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/openlayers/openlayers.github.io@master/en/v6.1.1/css/ol.css" type="text/css">
<style>
.map {
height: 400px;
width: 100%;
}
</style>
<script src="https://cdn.jsdelivr.net/gh/openlayers/openlayers.github.io@master/en/v6.1.1/build/ol.js"></script>
<title>Circle features</title>
</head>
<body>
<div id="map" class="map"></div>
<script type="text/javascript">
// features
var radius = 1600;
var center = [-1.733014, 51.982989]
var fcircle = new ol.Feature({
geometry: new ol.geom.Circle(
ol.proj.fromLonLat(center),
radius
)
});
fcircle.setStyle(new ol.style.Style({
stroke: new ol.style.Stroke({
color: 'blue',
width: 2
})
}));
var fcircular = new ol.Feature({
geometry: ol.geom.Polygon.circular(center, radius, 64).transform('EPSG:4326', 'EPSG:3857')
});
fcircular.setStyle(new ol.style.Style({
stroke: new ol.style.Stroke({
color: 'red',
width: 1
})
}));
// map
var view = new ol.View({
center: ol.proj.fromLonLat(center),
zoom: 14
});
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
source: new ol.source.OSM()
}),
new ol.layer.Vector({
source: new ol.source.Vector({
features: [fcircle, fcircular]
})
})
],
view
});
</script>
</body>
</html>
Upvotes: 0