Image layer with *locally* stored image - openlayers-3

I would like to add an image layer to a map using OpenLayers 3. The image file is stored locally, not on the web. The OL 2 documentation says that the image must be accessible on the web: http://dev.openlayers.org/docs/files/OpenLayers/Layer/Image-js.html, however, it seems to be possible to use a local basemap: Using openlayers with a local basemap?. There is no HTTP server running on the local system.
The starting point is the static image example on the OL website: http://openlayers.org/en/v3.12.1/examples/static-image.html
<!DOCTYPE html>
<html>
<head>
<title>Static Image</title>
<link rel="stylesheet" href="http://openlayers.org/en/v3.12.1/css/ol.css" type="text/css">
<script src="http://openlayers.org/en/v3.12.1/build/ol.js"></script>
</head>
<body>
<div id="map" class="map"></div>
<script>
// Map views always need a projection. Here we just want to map image
// coordinates directly to map coordinates, so we create a projection that uses
// the image extent in pixels.
var extent = [0, 0, 1024, 968];
var projection = new ol.proj.Projection({
code: 'xkcd-image',
units: 'pixels',
extent: extent
});
var map = new ol.Map({
layers: [
new ol.layer.Image({
source: new ol.source.ImageStatic({
attributions: [
new ol.Attribution({
html: '© xkcd'
})
],
url: 'http://imgs.xkcd.com/comics/online_communities.png',
projection: projection,
imageExtent: extent
})
})
],
target: 'map',
view: new ol.View({
projection: projection,
center: ol.extent.getCenter(extent),
zoom: 2,
maxZoom: 8
})
});
</script>
</body>
</html>
Here, http://imgs.xkcd.com/comics/online_communities.png should be replaced by the path to a local file. file://... does not work for me. The OS is Windows 7.

Related

ArcGIS 3.x to 4.x Migration

I was using ArcGIS JS API 3.10 and have a Github
repository to display GeoJSON data on a map but now I have to upgrade to
4.9 version I read 3.x to 4.x migration document published by ESRI and apply he changes like link location etc. but it’s not working anymore.
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=7,IE=9">
<meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
<title>ArcGIS GeoJSON Layer</title>
<!-- ArcGIS API for JavaScript CSS-->
<link rel="stylesheet" href="https://js.arcgis.com/4.9/esri/css/main.css">
#*<link rel="stylesheet" href="//js.arcgis.com/3.9/js/esri/css/esri.css">*#
<!-- Web Framework CSS - Bootstrap (getbootstrap.com) and Bootstrap-map-js (github.com/esri/bootstrap-map-js) -->
<link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">
<link rel="stylesheet" href="//esri.github.io/bootstrap-map-js/src/css/bootstrapmap.css">
<style>
html, body, #mapDiv {
height: 500px;
width: 100%;
}
</style>
<script src="https://js.arcgis.com/4.9/"></script>
<!-- ArcGIS API for JavaScript library references -->
#*<script src="//js.arcgis.com/3.10"></script>*#
<!-- Terraformer reference -->
<script src="/vendor/terraformer/terraformer.min.js"></script>
<script src="/vendor/terraformer-arcgis-parser/terraformer-arcgis-parser.min.js"></script>
<script>
require(["esri/Map",
"/Scripts/Refine.js",
"dojo/on",
"dojo/dom",
"dojo/domReady!"],
function (Map, GeoJsonLayer, on, dom) {
// Create map
var map = new Map("mapDiv", {
basemap: "gray",
center: [-122.5, 45.5],
zoom: 5
});
map.on("load", function () {
addGeoJsonLayer("http://113.197.55.251/api/punjab");
});
// Add the layer
function addGeoJsonLayer(url) {
// Create the layer
var geoJsonLayer = new GeoJsonLayer({
url: url
});
// Zoom to layer
geoJsonLayer.on("update-end", function (e) {
map.setExtent(e.target.extent.expand(1.2));
});
// Add to map
map.add(geoJsonLayer);
}
});
</script>
</head>
<body>
<div id="mapDiv"></div>
</body>
</html>

In ArcGIS 4.9 you have to use a MapView like below:
For the conversion between GeoJson and EsriJson, I suggest you the arcgis-to-geojson-utils library
Import the library in your html:
<script src="https://unpkg.com/#esri/arcgis-to-geojson-utils"></script>
javascript:
require([
"esri/Map",
"esri/views/MapView",
"esri/Graphic",
"esri/layers/FeatureLayer",
"esri/layers/support/Field",
"dojo/on",
"dojo/dom",
"dojo/domReady!"],
function (Map, MapView, Graphic, FeatureLayer, Field, on, dom) {
// Create mapView and map
var mapView = new MapView({
container: mapDiv,
map: new Map({
basemap: "gray"
}),
center: [-122.5, 45.5],
zoom: 5
}).when(function(mapView) {
makeRequest("http://113.197.55.251/api/punjab", function(response) {
createLayerFromGeoJSON(response, mapView);
});
});
// Request the geojson data using XmlHttpRequest
function makeRequest(url, callback) {
var xhr = new XMLHttpRequest();
xhr.open("GET", url, true);
xhr.setRequestHeader("Content-type", "application/json; charset=utf-8");
xhr.onreadystatechange = function() {
if (xhr.readyState == 4 && xhr.status == 200) {
callback(JSON.parse(xhr.response));
}
};
xhr.onerror = function(error) {
throw error;
}
xhr.send();
};
// Create the layer from the geojson data
function createLayerFromGeoJSON(geojson, mapView) {
// Convert geojson to esriJson using arcgis-to-geojson-utils library
var esriJson = ArcgisToGeojsonUtils.geojsonToArcGIS(geojson);
// Create an array of graphics from the esriJson
var graphics = esriJson.map(function(feature, i) {
return new Graphic({
geometry: {
type: "polygon",
rings: feature.geometry.rings
},
attributes: {
ObjectID: i,
Name: feature.attributes.Name
}
});
});
// Create a FeatureLayer from the graphics
var layer = new FeatureLayer({
title: "My feature layer",
source: graphics, // autocast as an array of esri/Graphic
geometryType: "polygon",
fields: [
new Field({
name: "ObjectID",
alias: "ObjectID",
type: "oid"
}),
new Field({
name: "Name",
alias: "Name",
type: "string"
}),
],
objectIdField: "ObjectID", // This must be defined when creating a layer from Graphics
renderer: {
type: "simple", // autocasts as new SimpleRenderer()
symbol: {
type: "simple-fill", // autocasts as new SimpleFillSymbol()
color: {r: 200, g: 200, b: 200, a: 0.5},
outline: { // autocasts as new SimpleLineSymbol()
width: 0.5,
color: "black"
}
}
}
});
mapView.map.add(layer);
return layer;
};
});

In ArcGis Js 4.x version you have to also declare a view constructor (MapView for 2D or SceneView for 3D). Here is a guide on how to set up 2D view: https://developers.arcgis.com/javascript/latest/sample-code/intro-mapview/index.html
Another way to add Json file is to convert your existing your json file to an esri json format, like in this guide: https://developers.arcgis.com/javascript/latest/sample-code/sandbox/index.html?sample=layers-featurelayer-collection.
Since I don't know your json file attributes I can't really provide a working sample, but its really simple.

Get Features in heatmap openlayers3

I want to get all features when I click on heat map in openlayers 3...It is possible or not? How to count the features in heat map and give heat map total count features label? thanks

Openlayers3 can do this easily,You can use getFeatures() to get all the features.
var features = heatlayer.getSource().getFeatures()
alert('count: '+features.length);
This method returns an array containing all the features,so you can use length to count.
<!DOCTYPE html>
<html>
<head>
<title>heatlayer count example</title>
<link rel="stylesheet" href="https://openlayers.org/en/v3.20.1/css/ol.css" type="text/css">
<!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
<script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
<script src="https://openlayers.org/en/v3.20.1/build/ol.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jspdf/1.2.61/jspdf.min.js"></script>
<style>
.map {
max-width: 566px;
}
</style>
</head>
<body>
<div id="map" class="map"></div>
<script>
var raster = new ol.layer.Tile({
source: new ol.source.OSM()
});
var heatlayer = new ol.layer.Heatmap({
source: new ol.source.Vector(),
blur: parseInt(14),
radius: parseInt(8)
});
var adddata = [[104.807799,30.232233],[106.803599,31.233225]];
//addfeature
for(var i = 0;i < adddata.length ; i++){
var feature = new ol.Feature({
geometry:new ol.geom.Point([adddata[i][0],adddata[i][1]])
});
heatlayer.getSource().addFeature(feature);
}
var map = new ol.Map({
layers: [raster,heatlayer],
target: 'map',
controls: ol.control.defaults({
attributionOptions: /** #type {olx.control.AttributionOptions} */ ({
collapsible: false
})
}),
view: new ol.View({
projection: 'EPSG:4326',
center:[104.07, 30.7],
zoom: 2
})
});
map.on('click', function(event){
var features = heatlayer.getSource().getFeatures()
alert('count: '+features.length);
});
</script>
</body>
</html>

Openlayers 3 WMTS

I am having an issue where I am trying to load a WMTS feed using Openlayers and seem not to be getting good results. For ArcGis services this seems to go through but not GeoServer's WMTS services. The code is as shown below. I keep getting a javascript error
TypeError: Argument 2 of CanvasRenderingContext2D.putImageData is not a finite floating-point value.
The code I am using is shown below. Regardless of changing the projection the error remains the same. Please advise. Raw Gist here
<!DOCTYPE html>
<html>
<head>
<title>WMTS example</title>
<script src="https://code.jquery.com/jquery-1.11.2.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"> </script>
<link rel="stylesheet" href="http://openlayers.org/en/v3.8.2/css/ol.css" type="text/css">
<script src="http://openlayers.org/en/v3.8.2/build/ol.js"></script>
<meta content="text/html;charset=utf-8" http-equiv="Content-Type">
<meta content="utf-8" http-equiv="encoding">
</head>
<body>
<div class="container-fluid">
<div class="row-fluid">
<div class="span12">
<div id="map" class="map"></div>
</div>
</div>
</div>
<script>
var projection = ol.proj.get('EPSG:4326');
var projectionExtent = projection.getExtent();
var size = ol.extent.getWidth(projectionExtent) / 256;
var resolutions = new Array(21);
var matrixIds = new Array(21);
for (var i=0; i<21; ++i) {
matrixIds[i] = "EPSG:4326:" + i;
}
var attribution = new ol.Attribution({
html: 'Tiles © <a href="http://services.arcgisonline.com/arcgis/rest/' +
'services/Demographics/USA_Population_Density/MapServer/">ArcGIS</a>'
});
var map = new ol.Map({
layers: [
new ol.layer.Tile({
source: new ol.source.OSM(),
opacity: 0.7
}),
new ol.layer.Tile({
opacity: 0.7,
source: new ol.source.WMTS({
attributions: [attribution],
url: 'http://suite.opengeo.org/geoserver/gwc/service/wmts',
layer: 'opengeo:countries',
matrixSet: 'ESPG:4326',
format: 'image/png',
style : 'default',
projection: projection,
tileGrid: new ol.tilegrid.WMTS({
origin: ol.extent.getTopLeft(projectionExtent),
resolutions: resolutions,
matrixIds: matrixIds
}),
wrapX: true
})
})
],
target: 'map',
controls: ol.control.defaults({
attributionOptions: /** #type {olx.control.AttributionOptions} */ ({
collapsible: false
})
}),
view: new ol.View({
center: [-13677832, 5213272],
//center: [-11158582, 4813697],
zoom: 1
})
});
</script>
</body>
</html>

Your resolutions array is just filled with undefineds, right? You should fill it with you desired resolutions.

You should to init your resolution array like this:
for (var z = 0; z < 21; ++z) {
resolutions[z] = size / Math.pow(2, z);
matrixIds[z] = "EPSG:4326:" + z;;
}
Did you set map's projection to ol.proj.get('EPSG:4326')?
var view = new ol.View({
center: [0, 0],
zoom: 1,
projection: ol.proj.get('EPSG:4326')
});

OpenLayers 3 WMS Layer - Misplaced tiles in EPSG:2180 projection

I'm trying to display map of Poland using OpenLayers 3. I need it to be in projection EPSG:2180. Ewerything is ok until I switch the projection.
This works fine:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script src="http://openlayers.org/en/v3.7.0/build/ol.js" type="text/javascript"></script>
<script src="proj4js/proj4-src.js" type="text/javascript"></script>
<script>
proj4.defs('EPSG:2180', "+proj=tmerc +lat_0=0 +lon_0=19 +k=0.9993 +x_0=500000 +y_0=-5300000 +ellps=GRS80 +units=m +no_defs");
function init()
{
var p = ol.proj.get('EPSG:3857');
var mapTiles = new ol.Map({
target: 'map',
renderer: 'canvas',
layers: [
new ol.layer.Tile({
source: new ol.source.TileWMS({
url: 'http://mapy.geoportal.gov.pl/wss/service/img/guest/ORTO/MapServer/WMSServer',
params: {
'LAYERS': 'Raster'
}
}),
isBaseLayer: true,
projection: p
})
],
view: new ol.View({
center: ol.proj.transform([19, 52], 'EPSG:4326', 'EPSG:3857'),
zoom: 6,
projection: p
})
});
}
</script>
</head>
<body onload="init()">
<div id="map"></div>
</body>
</html>
When i switch projection to EPSG:2180 tiles are misplaced.
Code with EPSG:2180
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>test</title>
<script src="http://openlayers.org/en/v3.7.0/build/ol.js" type="text/javascript"></script>
<script src="proj4js/proj4-src.js" type="text/javascript"></script>
<script>
proj4.defs('EPSG:2180', "+proj=tmerc +lat_0=0 +lon_0=19 +k=0.9993 +x_0=500000 +y_0=-5300000 +ellps=GRS80 +units=m +no_defs");
function init()
{
var p = ol.proj.get('EPSG:2180');
var mapTiles = new ol.Map({
target: 'map',
renderer: 'canvas',
layers: [
new ol.layer.Tile({
source: new ol.source.TileWMS({
url: 'http://mapy.geoportal.gov.pl/wss/service/img/guest/ORTO/MapServer/WMSServer',
params: {
'LAYERS': 'Raster',
'CRS': 'EPSG:2180'
}
}),
isBaseLayer: true,
projection: p
})
],
view: new ol.View({
center: ol.proj.transform([19, 52], 'EPSG:4326', 'EPSG:2180'),
zoom: 6,
projection: p
})
});
}
</script>
</head>
<body onload="init()">
<div id="map"></div>
</body>
</html>
Any idea what is the problem?
https://jsfiddle.net/b2L6qppd/

I have add one element - it prevent of axes problem.
params: {
'LAYERS': 'Raster',
'CRS': 'EPSG:2180',
'VERSION': '1.1.1'
}
try with this: jsfiddle.net/b2L6qppd/2/

openlayer geometric points won't show

I am new to openlayers and a beginner to javascript, but I have tried for 3 days and nights now. My code seems okay but there is something I am missing out and just can’t figure it out
I have this problem, I can’t find my geometric points on my map.
My code goes thus:
//html
<!doctype html>
<head>
<title> Me OpenStreetMap </title>
<link rel="stylesheet" href="../assets/ol3/css/ol.css" type="text/css" />
<link rel="stylesheet" href="../assets/ol3/css/samples.css" type="text/css" />
</head>
<body>
<div id="map"></div>
<script src="../assets/ol3/js/ol.js"></script>
<script>
// style for geometric layer
var meStyle = new ol.style.Circle({
radius: 20,
fill: new ol.style.Fill({
color: '#ff9900',
opacity: 1
}),
stroke: new ol.style.Stroke({
color: '#ffcc00',
opacity: 1
})
});
// geometric layer
var geoLayer = new ol.layer.Vector({
source : new ol.source.Vector({
projection : 'EPSG:3857',
url : '../data/json.json',
format: new ol.format.GeoJSON(),
style: meStyle
})
});
// create layer
var osmLayer = new ol.layer.Tile({
source : new ol.source.OSM()
});
// create view
var yaounde = new ol.proj.transform([11.5653, 3.86617],
'EPSG:4326', 'EPSG:3857'
);
var view = new ol.View({
center: yaounde,
zoom: 15
});
// create map
var map = new ol.Map({
target: 'map'
});
map.addLayer(osmLayer, geoLayer);
map.setView(view);
</script>
</body>
</html>
//geojson
{"type":"FeatureCollection",
"features":
[
{"type":"Feature","properties":{"Name":"","Description":""},"geometry":{"type":"Point","coordinates":[0.0,0.0]}},
{"type":"Feature","properties":{"Name":"1","Description":""},"geometry":{"type":"Point","coordinates":[11.50728,3.87471,0.0]}},
{"type":"Feature","properties":{"Name":"2","Description":""},"geometry":{"type":"Point","coordinates":[11.5072,3.8759,0.0]}},
{"type":"Feature","properties":{"Name":"3","Description":""},"geometry":{"type":"Point","coordinates":[11.5032,3.87556,0.0]}},
{"type":"Feature","properties":{"Name":"4","Description":""},"geometry":{"type":"Point","coordinates":[11.50291,3.87552,0.0]}},
{"type":"Feature","properties":{"Name":"5","Description":""},"geometry":{"type":"Point","coordinates":[11.50278,3.87573,0.0]}},
{"type":"Feature","properties":{"Name":"6","Description":""},"geometry":{"type":"Point","coordinates":[11.50316,3.87621,0.0]}},
{"type":"Feature","properties":{"Name":"7","Description":""},"geometry":{"type":"Point","coordinates":[11.50347,3.87611,0.0]}},
{"type":"Feature","properties":{"Name":"8","Description":""},"geometry":{"type":"Point","coordinates":[11.50314,3.8763,0.0]}},
{"type":"Feature","properties":{"Name":"9","Description":""},"geometry":{"type":"Point","coordinates":[11.50325,3.87652,0.0]}},
{"type":"Feature","properties":{"Name":"10","Description":""},"geometry":{"type":"Point","coordinates":[11.50356,3.87558,0.0]}},
{"type":"Feature","properties":{"Name":"11","Description":""},"geometry":{"type":"Point","coordinates":[11.5033,3.87564,0.0]}},
{"type":"Feature","properties":{"Name":"12","Description":""},"geometry":{"type":"Point","coordinates":[11.50397,3.87586,0.0]}},
{"type":"Feature","properties":{"Name":"13","Description":""},"geometry":{"type":"Point","coordinates":[11.50299,3.87641,0.0]}},
{"type":"Feature","properties":{"Name":"14","Description":""},"geometry":{"type":"Point","coordinates":[11.50279,3.8771,0.0]}},
{"type":"Feature","properties":{"Name":"15","Description":""},"geometry":{"type":"Point","coordinates":[11.50269,3.87723,0.0]}},
{"type":"Feature","properties":{"Name":"16","Description":""},"geometry":{"type":"Point","coordinates":[11.50258,3.87722,0.0]}},
{"type":"Feature","properties":{"Name":"17","Description":""},"geometry":{"type":"Point","coordinates":[11.49122,3.8738,0.0]}},
{"type":"Feature","properties":{"Name":"18","Description":""},"geometry":{"type":"Point","coordinates":[11.48567,3.87447,0.0]}},
{"type":"Feature","properties":{"Name":"19","Description":""},"geometry":{"type":"Point","coordinates":[11.48548,3.88107,0.0]}},
{"type":"Feature","properties":{"Name":"20","Description":""},"geometry":{"type":"Point","coordinates":[11.48526,3.8812,0.0]}},
{"type":"Feature","properties":{"Name":"21","Description":""},"geometry":{"type":"Point","coordinates":[11.48614,3.88044,0.0]}},
{"type":"Feature","properties":{"Name":"22","Description":""},"geometry":{"type":"Point","coordinates":[11.48638,3.88033,0.0]}},
{"type":"Feature","properties":{"Name":"23","Description":""},"geometry":{"type":"Point","coordinates":[11.48641,3.88053,0.0]}},
{"type":"Feature","properties":{"Name":"24","Description":""},"geometry":{"type":"Point","coordinates":[11.4868,3.88029,0.0]}},
{"type":"Feature","properties":{"Name":"25","Description":""},"geometry":{"type":"Point","coordinates":[11.48772,3.87994,0.0]}},
{"type":"Feature","properties":{"Name":"26","Description":""},"geometry":{"type":"Point","coordinates":[11.4887,3.88057,0.0]}},
{"type":"Feature","properties":{"Name":"27","Description":""},"geometry":{"type":"Point","coordinates":[11.48869,3.88057,0.0]}},
{"type":"Feature","properties":{"Name":"28","Description":""},"geometry":{"type":"Point","coordinates":[11.48868,3.8807,0.0]}},
{"type":"Feature","properties":{"Name":"29","Description":""},"geometry":{"type":"Point","coordinates":[11.4888,3.88071,0.0]}},
{"type":"Feature","properties":{"Name":"30","Description":""},"geometry":{"type":"Point","coordinates":[11.49206,3.8775,0.0]}},
{"type":"Feature","properties":{"Name":"31","Description":""},"geometry":{"type":"Point","coordinates":[11.49251,3.87748,0.0]}},
{"type":"Feature","properties":{"Name":"32","Description":""},"geometry":{"type":"Point","coordinates":[11.4923,3.87783,0.0]}},
{"type":"Feature","properties":{"Name":"33","Description":""},"geometry":{"type":"Point","coordinates":[11.49273,3.87822,0.0]}}
]
}
The OpenStreet map appears by I can’t find the points

It is very simple to solve:
map.addLayer(osmLayer);
map.addLayer(geoLayer);
The addLayer method accepts a layer, only one. A working demo with your code.

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