Develop Reference

rendering opensensemap IDW features via openlayers

I'm trying to render some extra features on map using openlayers. The features can be fetched from the opensensemap API, but for some reason they are not rendered. As I am completely new to openlayers, and dont know much javascript either, I hope for some help.
live code: https://ttnkn.github.io/map/pax/
var GeoStyle = {
'Point': new ol.style.Style({
image: new ol.style.Icon({
src: '../img/bike.png',
scale: 0.075,
})
}),
'Circle': new ol.style.Circle({
fill: new ol.style.Fill({
color: 'rgba(255,255,255,0.4)'
}),
stroke: ol.style.Stroke({
color: '#3399CC',
width: 1.25
}),
radius: 5
})
};
function GeoStyleFunc (feature,resolution) {
return GeoStyle[feature.getGeometry().getType()];
}
var VectorSource = new ol.source.Vector({
format: new ol.format.GeoJSON(),
url: 'https://api.opensensemap.org/boxes?bbox=9.118815,47.653129,9.228427,47.698786&format=geojson&exposure=mobile',
});
var VectorTile = new ol.source.XYZ({
url: 'http://tile.memomaps.de/tilegen/{z}/{x}/{y}.png ',
attributions: 'Map © OSM | Tiles © MeMoMaps | Data © OpenSenseMap'
});
var map = new ol.Map({
target: document.getElementById('map'),
layers: [
new ol.layer.Tile({
source: VectorTile
}),
new ol.layer.Vector({
source: VectorSource,
style: GeoStyleFunc
})
],
controls: ol.control.defaults({ zoom: true, attribution: true }),
view: new ol.View({
center: ol.proj.fromLonLat([9.173, 47.672]),
zoom: 15,
maxZoom: 17,
minZoom: 13
})
});
var url = 'https://api.opensensemap.org/statistics/idw?bbox=9.118815,47.653129,9.228427,47.698786&phenomenon=Temperatur&gridType=hex&cellWidth=2';
fetch(url).then(value => {
value.json().then(value => {
var featureJson = value.data.featureCollection;
var features = (new ol.format.GeoJSON()).readFeatures(featureJson);
var vectorSourceHEX = new ol.source.Vector({
features: features,
projection: ol.proj.get('EPSG:4326')
});
var vectorLayer = new ol.layer.Vector({
source: vectorSourceHEX,
// style: GeoStyleFunc
});
map.addLayer(vectorLayer);
});
}, error => { console.log(error) });

The projection option isn't used in vector sources. If you use readFeatures you must transform the data to the view projection (when you construct a source with a url that is done automatically).
var features = (new ol.format.GeoJSON()).readFeatures(featureJson, {
dataProjection: 'EPSG:4326',
featureProjection: map.getView().getProjection()
});
var vectorSource = new ol.source.Vector({
features: features,
});

OpenLayers 5 wms tiled map wrapping with Gall-Peters projection

With OL5 I'm trying to use a map with Gall-Peters projection with this definition:
var projname = 'EPSG:22';
var projdef = '+proj=cea +lon_0=0 +lat_ts=45 +x_0=0 +y_0=0 +ellps=WGS84 +units=m +no_defs';
var petersProjection = new Projection({
code: projname,
units: 'm',
extent: [-14192432.0000000000000000,-8984819.0000000000000000, 14192432.0000000000000000,8928365.0000000000000000]
});
proj4.defs(projname, projdef);
register(proj4);
GeoServer is used to serve the map as WMS and WMTS also in Gall-Peters projection.
In OL client the map is not wrapped across the 180° meridian. It only shows "one world".
When I switch the projection to EPSG:4326 or EPSG:3857 I get a continous wrapped map.
I'm stuck here.
Is something wrong with my projection definition?
Is OL only able to wrap with standard projections?
How can I get a wrapped map in Gall-Peters projection?
For reference here are my definitions of layer, view and map:
var basiskarte_source = new TileWMS({
url: geoserver_url,
serverType: 'geoserver',
params: {'FORMAT': 'image/png',
'VERSION': '1.1.1',
TILED: true,
LAYERS: 'eg:basiskarte',
tilesOrigin: -180 + "," + -90,
srs: 'EPSG:22'
},
projection : petersProjection
});
var wms_geoserver_tiled_layer =
new TileLayer({
title : 'gall-peters-map',
type : 'base',
visible : true,
source: basiskarte_source
});
var myview = new View({
center: fromLonLat([36.8394, -1.2743], petersProjection),
projection: projectionInUse,
zoom: 1,
rotation: deg2rad(180)
});
var map = new Map({
target: 'map',
layers: [
new LayerGroup({
title : 'Basiskarte',
layers: [wms_geoserver_tiled_layer]
})
],
view: myview
});

OpenLayers 4 zoom to cluster

Im using OpenLayers 4 and have a layer with an ol.source.Cluster as source. When I click on a clustered point I want to zoom in to the extent of the original points that makes up the cluster. My problem is that I can not find these original points anywhere.
I have tried to calculate an extent from the distance I use on the cluster but the result is not satisfying.
Any idea how to determine which the original points behind a cluster point are?
<html>
<head>
<title>Cluster</title>
<link rel="stylesheet" href="https://openlayers.org /en/v4.1.1/css/ol.css" type="text/css">
<script src="https://openlayers.org/en/v4.1.1/build/ol.js"></script>
</head>
<body>
<div id="map" class="map"></div>
<script>
var geojsonObject = {
'type': 'FeatureCollection',
'crs': {
'type': 'name',
'properties': {
'name': 'EPSG:3857'
}
},
'features': [{
'type': 'Feature',
'geometry': {
'type': 'Point',
'coordinates': [0, 0]
}
}, {
'type': 'Feature',
'geometry': {
'type': 'Point',
'coordinates': [9, 9]
}
},{
'type': 'Feature',
'geometry': {
'type': 'Point',
'coordinates': [10, 10]
}
}]
};
var source = new ol.source.Vector({
features: (new ol.format.GeoJSON()).readFeatures(geojsonObject)
});
var clusterSource = new ol.source.Cluster({
source: source,
distance: 30
});
var layer = new ol.layer.Vector({
source: clusterSource
});
var select = new ol.interaction.Select({
layers: [layer]
});
var view = new ol.View({
center: [5, 5],
zoom: 20
});
var map = new ol.Map({
target: 'map',
layers: [new ol.layer.Tile({
source: new ol.source.OSM()
}),layer],
view: view
});
map.addInteraction(select);
var selectedFeatures = select.getFeatures();
selectedFeatures.on('add', function(event) {
// event.target only contains the clustered point
var feature = event.target.item(0);
});
</script>
</body>
</html>

I found the answer myself in a OpenLayers example.
In the selected feature function you can do
var originalFeatures = feature.get('features');
To get the original features, and then in my case to zoom to the extent
var extent = new ol.extent.createEmpty();
originalFeatures.forEach(function(f, index, array){
ol.extent.extend(extent, f.getGeometry().getExtent());
});
map.getView().fit(extent, map.getSize());

You can get the features in the cluster from:
source.getFeatures()
You can get the extent from:
source.getExtent()
Where source is an instance of ol.source.Cluster

Openlayers 3 circles from geojson not working with layer tile source different from TileWMS

I am working with openlayers 3 with a layer from mapbox or openstreetmap and I need to draw some circles on it.
I am able to print the circles with a view with a projection EPSG:4326, but then I have no map. Changing the projection with a transform the map is displayed, but the points are all together. The only way I am made it work is using TileWMS as a source, but I am not able to use it in production environment
Here is my code:
version 1: working with TileWMS
var source = new ol.source.GeoJSON({
url: 'geojson url'
});
var pointsLayer = new ol.layer.Vector({
source: source,
style: new ol.style.Style({
image: new ol.style.Circle({
radius: 15,
fill: new ol.style.Fill({color: 'rgba(170,33,33, 0.8)'}),
stroke: new ol.style.Stroke({color: 'rgba(170,33,33, 0.3)', width: 8})
})
})
});
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
title: "Global Imagery",
source: new ol.source.TileWMS({
url: 'http://maps.opengeo.org/geowebcache/service/wms',
params: {LAYERS: 'bluemarble', VERSION: '1.1.1'}
})
}),
pointsSource
],
view: new ol.View({
projection: 'EPSG:4326',
center: [-82.3, -10.65],
zoom: 3
})
});
This is the result
Using mapbox or osm, failing:
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
source: new ol.source.XYZ({
url: 'http://api.tiles.mapbox.com/v4/XXXXX.kcp9cpdn/{z}/{x}/{y}.png?access_token=token'
})
}),
/*
new ol.layer.Tile({
source: new ol.source.OSM()
}),*/
pointsSource
],
view: new ol.View({
projection: 'EPSG:4326',
center: [-82.3, -10.65],
zoom: 3
})
});
This is the result
And finally, changing the view the map is displayed but the circles
var map = new ol.Map({
target: 'map',
layers: [
new ol.layer.Tile({
source: new ol.source.XYZ({
url: 'http://api.tiles.mapbox.com/v4/XXXXX.kcp9cpdn/{z}/{x}/{y}.png?access_token=token'
})
}),
/*
new ol.layer.Tile({
source: new ol.source.OSM()
}),*/
pointsSource
],
view: new ol.View({
center: ol.proj.transform([-82.3, -10.65], 'EPSG:4326', 'EPSG:3857'),
zoom: 3
})
});
And the result
Is there a way to make this work?
Thanks in advance.

I found the solution, here it is for it is helping anyone
Following this answer in gis stackexchange https://gis.stackexchange.com/a/118818/42868 There is an unstable option for the ol.source.GeoJSON object, so adding it in this way made it work
var source = new ol.source.GeoJSON({
url: 'geojson url',
projection: 'EPSG:3857'
});

how to add markers with OpenLayers 3

I'm trying to add makers on a OpenLayers 3 map.
The only example I have found is this one in the OpenLayers example list.
But the example uses ol.Style.Icon instead of something like OpenLayers.Marker in OpenLayers 2.
First Question
The only difference would be that you have to set the image Url but is it the only way to add a marker?
Also OpenLayers 3 doesn't seem to come with marker images so it would make sense if there's no other way than ol.Style.Icon
Second Question
It would be really nice if someone could give me an example of a function to add markers or icons after the map is loaded.
From what I understand in the example, they create a layer for the icon
var iconFeature = new ol.Feature({
geometry: new ol.geom.Point(ol.proj.transform([-72.0704, 46.678], 'EPSG:4326', 'EPSG:3857')),
name: 'Null Island',
population: 4000,
rainfall: 500
});
var iconStyle = new ol.style.Style({
image: new ol.style.Icon(/** #type {olx.style.IconOptions} */ ({
anchor: [0.5, 46],
anchorXUnits: 'fraction',
anchorYUnits: 'pixels',
opacity: 0.75,
src: 'data/icon.png'
}))
});
iconFeature.setStyle(iconStyle);
var vectorSource = new ol.source.Vector({
features: [iconFeature]
});
var vectorLayer = new ol.layer.Vector({
source: vectorSource
});
Then they set the icon layer when they initialize the map
var map = new ol.Map({
layers: [new ol.layer.Tile({ source: new ol.source.OSM() }), vectorLayer],
target: document.getElementById('map'),
view: new ol.View2D({
center: [0, 0],
zoom: 3
})
});
If I want to add many markers, do I have to create 1 layer for each marker?
How could I add many markers to a layer? I can't figure out how this part would look
like
var vectorSource = new ol.source.Vector({
features: [iconFeature]
});
var vectorLayer = new ol.layer.Vector({
source: vectorSource
});
Thank you

Q1. Markers are considered deprecated in OpenLayers 2, though this isn't very obvious from the documentation. Instead, you should use an OpenLayers.Feature.Vector with an externalGraphic set to some image source in its style. This notion has been carried over to OpenLayers 3, so there is no marker class and it is done as in the example you cited.
Q2. The ol.source.Vector takes an array of features, note the line, features: [iconFeature], so you would create an array of icon features and add features to that, eg:
var iconFeatures=[];
var iconFeature = new ol.Feature({
geometry: new ol.geom.Point(ol.proj.transform([-72.0704, 46.678], 'EPSG:4326',
'EPSG:3857')),
name: 'Null Island',
population: 4000,
rainfall: 500
});
var iconFeature1 = new ol.Feature({
geometry: new ol.geom.Point(ol.proj.transform([-73.1234, 45.678], 'EPSG:4326',
'EPSG:3857')),
name: 'Null Island Two',
population: 4001,
rainfall: 501
});
iconFeatures.push(iconFeature);
iconFeatures.push(iconFeature1);
var vectorSource = new ol.source.Vector({
features: iconFeatures //add an array of features
});
var iconStyle = new ol.style.Style({
image: new ol.style.Icon(/** #type {olx.style.IconOptions} */ ({
anchor: [0.5, 46],
anchorXUnits: 'fraction',
anchorYUnits: 'pixels',
opacity: 0.75,
src: 'data/icon.png'
}))
});
var vectorLayer = new ol.layer.Vector({
source: vectorSource,
style: iconStyle
});
Obviously, this could be more elegantly handled by putting all of the ol.Feature creation inside a loop based on some data source, but I hope this demonstrates the approach. Note, also, that you can apply a style to the ol.layer.Vector so that it will be applied to all features being added to the layer, rather than having to set the style on individual features, assuming you want them to be the same, obviously.
EDIT: That answer doesn't seem to work. Here is an updated fiddle that works by adding the features (icons) to the empty vector source in a loop, using vectorSource.addFeature and then adds the whole lot to the layer vector afterwards. I will wait and see if this works for you, before updating my original answer.

there's a good tutorial at: http://openlayersbook.github.io
not tested but may helpful
var features = [];
//iterate through array...
for( var i = 0 ; i < data.length ; i++){
var item = data[i]; //get item
var type = item.type; //get type
var longitude = item.longitude; //coordinates
var latitude = item.latitude;
/*....
* now get your specific icon...('..../ic_customMarker.png')
* by e.g. switch case...
*/
var iconPath = getIconPath(type);
//create Feature... with coordinates
var iconFeature = new ol.Feature({
geometry: new ol.geom.Point(ol.proj.transform([longitude, latitude], 'EPSG:4326',
'EPSG:3857'))
});
//create style for your feature...
var iconStyle = new ol.style.Style({
image: new ol.style.Icon(/** #type {olx.style.IconOptions} */ ({
anchor: [0.5, 46],
anchorXUnits: 'fraction',
anchorYUnits: 'pixels',
opacity: 0.75,
src: iconPath
}))
});
iconFeature.setStyle(iconStyle);
features.push(iconFeature);
//next item...
}
/*
* create vector source
* you could set the style for all features in your vectoreSource as well
*/
var vectorSource = new ol.source.Vector({
features: features //add an array of features
//,style: iconStyle //to set the style for all your features...
});
var vectorLayer = new ol.layer.Vector({
source: vectorSource
});
map.addLayer(vectorLayer);

var exampleLoc = ol.proj.transform(
[131.044922, -25.363882], 'EPSG:4326', 'EPSG:3857');
var map = new ol.Map({
target: 'map',
renderer: 'canvas',
view: new ol.View2D({
projection: 'EPSG:3857',
zoom: 3,
center: exampleLoc
}),
layers: [
new ol.layer.Tile({source: new ol.source.MapQuest({layer: 'osm'})})
]
});
map.addOverlay(new ol.Overlay({
position: exampleLoc,
element: $('<img src="resources/img/marker-blue.png">')
.css({marginTop: '-200%', marginLeft: '-50%', cursor: 'pointer'})
.tooltip({title: 'Hello, world!', trigger: 'click'})
}));
map.on('postcompose', function(evt) {
evt.vectorContext.setFillStrokeStyle(
new ol.style.Fill({color: 'rgba(255, 0, 0, .1)'}),
new ol.style.Stroke({color: 'rgba(255, 0, 0, .8)', width: 3}));
evt.vectorContext.drawCircleGeometry(
new ol.geom.Circle(exampleLoc, 400000));
});
var exampleKml = new ol.layer.Vector({
source: new ol.source.KML({
projection: 'EPSG:3857',
url: 'data/example.kml'
})
});
map.addLayer(exampleKml);

We just finished updating our website NUFOSMATIC from ol2 to ol6. Both the ol2 and ol3 code is on the site. This includes Matt Walker's ol-layerswitcher https://github.com/walkermatt replacing the missing ol2 layerswitcher. We actually updated three map applications; HEATMAP replaces the Patrick Wied (http://www.patrick-wied.at) ol2 heatmap with the native ol6 heatmap.
Only took 6 days. Wonder why we waited this long... oh, yeah, we have day jobs...