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Openlayers3 - fractional zoom on touch device using pinch gesture?

Openlayers3 can display a map at a fractional zoom level programmatically by specifying a fractional number in setZoom().
However, I want my users to be able to get a fractional zoom level on a mobile touch-driven device (ie, a smart phone). Pinch or reverse pinch zooms out/in by jumping to the nearest whole zoom level when the fingers are removed from the screen.
How can a touch/mobile user get Openlayers3 to stay at the exact extent (fractional zoom level) that the user has pinched to?
Is there something I can add to the javascript for my Openlayers3 map or view to get this to work as desired?
In particular, I note that Openlayers3 has a ol.interaction.PinchZoom() class ( https://openlayers.org/en/latest/apidoc/ol.interaction.PinchZoom.html ). This is a subclass of ol.interaction.Pointer which has a handleUpEvent and a handleEvent (which should be a function). So in theory, I should be able to either replace the handleUpEvent in PinchZoom OR replace the default PinchZoom interaction with one that has a custom event handler function. But with both of these approaches, I can't get my new handleUpEvent function to be called.
(While trawling the OL code for PinchZoom I have found that the default PinchZoom does what I want if one finger is lifted from the touch-screen before the other finger, but I still want to get this working when both fingers are lifted simultaneously.)
Here is what I've tried so far...
FIRST ATTEMPT - This just attempts to replace the standard PinchZoom's handleUpEvent with a custom one, and set this as the only interaction for the map. However, the event function is never called (never logs anything).
function handleUpEvent(evt) {
console.log("Up event handler");
return true; // Stop drag
}
map = new ol.Map({
layers: [],
target: 'map',
controls: controls,
interactions: [new ol.interaction.PinchZoom({handleEvent: handleUpEvent})],
view: new ol.View({projection: projCode})
});
SECOND ATTEMPT - This attempt is based on the actual OL code for creating the standard PinchZoom interaction. In this case, all my event handler functions DO get called, the number of touches ( targetPointers ) is always zero (as logged). I'm no javascript guru, but I suspect that this is because the symbols in ol.js are different to in ol-debug.js which I'm basing this on. In fact I had to declare targetPointers myself to even get this to run, even though it is declared by OL itself already (but presumably using a different symbol name in the non-debug version).
function handleDownEvent(mapBrowserEvent) {
console.log("DOWN event handler");
this.anchor_ = null;
this.lastDistance_ = undefined;
this.lastScaleDelta_ = 1;
mapBrowserEvent.map.render();
return true; // Start drag
}
function handleDragEvent(mapBrowserEvent) {
if ( this.targetPointers.length < 2 ) {
console.log("DRAG event ignored - touches ", this.targetPointers.length);
} else {
console.log("DRAG event handled");
var scaleDelta = 1.0;
var touch0 = this.targetPointers[0];
var touch1 = this.targetPointers[1];
var dx = touch0.clientX - touch1.clientX;
var dy = touch0.clientY - touch1.clientY;
// distance between touches
var distance = Math.sqrt(dx * dx + dy * dy);
if (this.lastDistance_ !== undefined) {
scaleDelta = this.lastDistance_ / distance;
}
this.lastDistance_ = distance;
if (scaleDelta != 1.0) {
this.lastScaleDelta_ = scaleDelta;
}
var map = mapBrowserEvent.map;
var view = map.getView();
var resolution = view.getResolution();
// scale anchor point.
var viewportPosition = map.getViewport().getBoundingClientRect();
var centroid = ol.interaction.Pointer.centroid(this.targetPointers);
centroid[0] -= viewportPosition.left;
centroid[1] -= viewportPosition.top;
this.anchor_ = map.getCoordinateFromPixel(centroid);
// scale, bypass the resolution constraint
map.render();
ol.interaction.Interaction.zoomWithoutConstraints(
map, view, resolution * scaleDelta, this.anchor_);
}
}
function handleUpEvent(mapBrowserEvent) {
console.log("UP event handler");
return true; // Stop drag
}
var pinchZoom = new ol.interaction.Pointer({
handleDownEvent: handleDownEvent,
handleDragEvent: handleDragEvent,
handleUpEvent: handleUpEvent
});
pinchZoom.targetPointers = [];
map = new ol.Map({
interactions: ol.interaction.defaults().extend([pinchZoom]),
layers: [
new ol.layer.Tile({
source: new ol.source.TileJSON({url: 'https://api.tiles.mapbox.com/v3/mapbox.geography-class.json?secure'})
})
],
target: 'map',
view: new ol.View({center: [0, 0], zoom: 3})
});

The problems with your attempts:
First attempt
The option handleEvent for ol.interaction.PinchZoom does not exists. That is why your callback is not executed.
Second attempt
As you already noted you try to use openlayers internals. This might work with the debug build but will not work in the release build as the names are different than.
Solution
Add the option to keep a fractional resolution at the pinch zoom end in the openlayers sources.
Issue: https://github.com/openlayers/ol3/issues/6223
Pull request: https://github.com/openlayers/ol3/issues/6224
The pinch zoom will by default keep the fractional zoom level as chosen by the user .. starting with OpenLayers 3.20
An earlier idea:
As an example I added the option keepFractionalZoomLevel to ol.interaction.PinchZoom: https://github.com/aAXEe/ol3/commit/7639cb20d17858492652896bcd4a6ff7992a9bb0
See this fiddle for a working example: https://jsfiddle.net/wm78prro/5/
Note: The fiddle uses a custom openlayers build: https://github.com/aAXEe/ol3/pull/1
The deploy url is: https://deploy-preview-1--pump-attendant-rhinoceros-42285.netlify.com/ol-debug.js
Does this example behave as you want?
As this may be usefull for others we can try to integrate it into openlayers.

How do I access and hide markers created by loadGeoJson()?

I am loading custom coordinates into my map application via JSON. I have been able to find out how to color code the markers based on feature properties, but one of my next steps will be to create filters to show or hide markers based on the properties.
My code starts like this:
var map;
var infowindow = new google.maps.InfoWindow();
function initialize()
{
var mapCanvas = document.getElementById('map');
var mapOptions = {
mapTypeId: google.maps.MapTypeId.ROADMAP
}
map = new google.maps.Map(mapCanvas, mapOptions);
map.data.loadGeoJson('/map_json.php', null, SetBounds);
map.data.setStyle(function(feature) {
var color = 'FF0000';
var symbol = '%E2%80%A2'; // dot
// color selection code here [...]
return /** #type {google.maps.Data.StyleOptions} */ {
icon: 'http://chart.apis.google.com/chart?chst=d_map_pin_letter_withshadow&chld=' + symbol + '|' + color
};
}
I already found how I can access the imported data through a jquery autocomplete search:
$(input).autocomplete({
minLength: 0,
source: function(request, response) {
data = [];
map.data.forEach(function(feature)
{
var str = request.term.toUpperCase();
if (String(feature.getProperty('name')).toUpperCase().indexOf(str) > -1)
{
data.push({id: feature.getProperty('id'), name: feature.getProperty('name'), address: feature.getProperty('address')});
}
});
response(data);
},
select: function(event, ui)
{
map.data.forEach(function(feature)
{
if (feature.getProperty('id') == ui.item.id)
{
var content = GetContent(feature);
infowindow.setContent(content);
infowindow.setPosition(feature.getGeometry().get());
infowindow.setOptions({pixelOffset: new google.maps.Size(0, -34)});
infowindow.open(map);
// zoom in
map.setZoom(15);
map.panTo(feature.getGeometry().get());
return false;
}
});
}
})
.autocomplete().data('uiAutocomplete')._renderItem = function(ul, item)
{
return $('<li>')
.append('<a>' + item.name + ' (ID: ' + item.id + ')<br>' + item.address + '</a>')
.appendTo(ul)
};
So using this same principle to run my filters is not a problem.
The problem is that I have not found a way yet to access the visible markers based on the feature information that I have in map.data.
All the examples I found so far are based on the principle of manually adding markers and storing them in an array to access later, e.g.:
var marker = new google.maps.Marker({
position: myLatLng,
map: map,
title: 'Hello World!'
});
But I don't have that - I load the entire set of data using getGeoJson().
How can I access the marker and manipulate it (e.g. hide it or show it) based on the information I can access using map.data.forEach()?
--- Update ---
Here are more details on the project.
The map will markers that are generated from a list of customers. The customers have different categories and properties, so a typical entry form the GeoJSON string would look like this:
{"type":"Feature","geometry":{"type":"Point","coordinates":[0,0]},"properties":{"name":"Customer 1","id":"1001","address":"1234 Test Street, Test City, TX 12345, USA","category":"vendor","active":1}}
Also on the map is a filter box with checkboxes that are checked by default. Clicking any of them will run the filtering code that should hide or remove the markers that are associated with any customers that match that filter.
So if I disable the checkbox that filters "inactive", then only customers with the property "active":1 will remain on the map. If I disable the checkbox that filters "vendors", then all customers with the category "vendor" will be hidden.
Checking the checkboxes again later will undo the hiding of these entries.
What I have found in my research is a lot of mentioning of markers, but ONLY if they are added manually - not via GeoJSON import.
I can see a few potential solutions to my problem - I could ignore the GeoJSON format and instead import the client list into jQuery manually and parse it from there into markers that then go into an array. But then why use the GeoJSON format at all?
My current solution of using map.data.setStyle() (see comment) seems to work and do the job. But I am curious if there isn't another more direct way.
I figured, the filter function would go through all data (map.data.forEach()) to locate any items that should be hidden based on the filters, and then each item would communicate to its associated marker that the marker needs to be hidden. But it is this association that I have not been able to figure out so far.
When I loop through all features (map.data.forEach()), I have access to the data I uploaded, but not to the markers that were placed as a result of the import.
My question is if there is a direct way to access the marker from the feature.
I hope this is clearer now.
--- Update ---
I created a very simple jsfiddle for it:
http://jsfiddle.net/semmelbroesel/9bv68ngp/
This is the concept I want to achieve, and it works as is. My only question is if there is another way to achieve the same results by directly accessing the placed markers instead of using setStyle() to hide/show them.

You don't need to use forEach, since setStyle does already traverse the Features.
If you declare the styling function as:
map.data.setStyle(function(feature) {
var color = 'FF0000';
var symbol = '%E2%80%A2'; // dot
return /** #type {google.maps.Data.StyleOptions} */ {
visible: feature.getProperty('active'), // this links visibility to feature property
icon: 'http://chart.apis.google.com/chart?chst=d_map_pin_letter_withshadow&chld=' + symbol + '|' + color
};
});
You don't need to call the method again, since the style gets bound to the feature property. Setting the active property to false will propagate to the marker style seamlessly.
After that, you can make your filters like (rough example)
var setFilter = function(property, value) {
map.data.forEach(function(feature) {
feature.setProperty('active', feature.getProperty(property) === value);
});
};
and calling for example setFilter('name','John');
Again, this is a rough example. I'd rather implement the filtering method on the google.maps.Data prototype, but this should point you in the right direction.

can't change marker icons / colors in mapbox

I'm manipulating the mapbox marker radius example here:
https://www.mapbox.com/mapbox.js/example/v1.0.0/marker-radius-search/
to attempt to change the color / icon of the markers within a certain radius of a random point, but the colors aren't changing despite the properties being registered as changed. Here's my code:
clusterLayer = L.mapbox.featureLayer('examples.map-h61e8o8e').on('ready', function(e) {
clusterGroup = new L.MarkerClusterGroup({
showCoverageOnHover: false,
animateAddingMarkers: true
});
e.target.eachLayer(function(layer) {
clusterGroup.addLayer(layer);
layerArray.push(layer);
});
map.addLayer(clusterGroup);
});
window.setTimeout(eventFunction,eventTiming);
function eventFunction(){
clusterLayer.setFilter(affectMarker);
}
function affectMarker(feature) {
var fLat = feature.geometry.coordinates[1];
var fLng = feature.geometry.coordinates[0];
var fPt = L.latLng(fLat,fLng);
var dist = eventPt.distanceTo(fPt);
if (dist < eventRadius){
feature.properties['marker-color'] = eventColorNegative;
feature.properties['marker-symbol'] = 'danger';
}
}
Why doesn't this work? I've verified that it is returning valid points.
Note also that the markers being used are MakiMarkers

I found two ways to do this, though neither, I think, is as ideal as being able to do so with the code above. The first is, rather than to use setFilter, use eachLayer:
clusterLayer.eachLayer(affectMarker);
and then in the loop, use setIcon:
layer.feature.properties['marker-color'] = eventColorNegative;
layer.feature.properties['marker-symbol'] = 'danger';
layer.setIcon(L.mapbox.marker.icon(layer.feature.properties));
The other way is to first include the MakiMarkers extension (which I believe has been deprecated and rolled into Mapbox):
https://github.com/jseppi/Leaflet.MakiMarkers
and then use this syntax:
layer.setIcon(L.MakiMarkers.icon({icon: "danger", color: eventColorNegative}));

Assign ID to marker in leaflet

So i try to achieve a result as on foursquare: https://foursquare.com/explore?cat=drinks&mode=url&near=Paris which is when you clik on a marker on the map, it scrolls through the listed of restaurants on the right -hand side of the screen to the ad hoc restaurant, and highlights it through CSS. Conversely, when you click on the restaurant on the list, it highlights it on the map.
I am using skobbler/leaflet. I think I can achieve this by amending dynamically CSS as shown in this example: http://jsfiddle.net/gU4sw/7/ + a scroll to destination script already in place in the page.
To achieve this however, it looks like I need to assign an ID within the markers (2 markers below):
var marker = L.marker([52.52112, 13.40554]).addTo(map);
marker.bindPopup("Hello world!<br>I am a popup1.", { offset: new L.Point(-1, -41) }).openPopup();
var marker = L.marker([52.53552, 13.41994]).addTo(map);
marker.bindPopup("Hello world!<br>I am a popup2.", { offset: new L.Point(-1, -41) }).openPopup();
Question is: How can I assign an marker ID to trigger css change in the corresponding element within my html page?
My knowledge of JS is very limited, but may be there's a nice and easy solution out there, thx

I've been looking for a nice way to do this and as far as I can tell there is still no built-in way (using leaflet) to give a marker an ID. I know I'm a bit late to answering this but hopefully it will help others who stumble upon this question. As far as I can tell there are two main issues here:
Problem #1:
Unless you save your markers to an object or map, described below, there is no easy programmatic way of accessing them later on. For example - A user clicks something OUTSIDE the map that corresponds to a marker INSIDE the map.
Problem #2:
When a user clicks on a marker INSIDE the map, there is no built in way to retrieve the ID of that marker and then use it to highlight a corresponding element or trigger an action OUTSIDE the map.
Solutions
Using a one or more of these options will help address the issues described above. I'll start with the one mentioned in the previous answer. Here is the working pen, which holds all the code found below.
Option #1:
Save each marker, using a hardcoded or dynamic ID, inside an object -
// Create or retrieve the data
var data = [
{
name: 'Bob',
latLng: [41.028, 28.975],
id: '2342fc7'
}, {...}, {...}
];
// Add an object to save markers
var markers = {};
// Loop through the data
for (var i = 0; i < data.length; i++) {
var person = data[i];
// Create and save a reference to each marker
markers[person.id] = L.marker(person.latLng, {
...
}).addTo(map);
}
Similar to the other answer you can now access a single marker by using -
var marker = markers.2342fc7; // or markers['2342fc7']
Option #2:
While leaflet doesn't provide a built-in 'id' option for markers, you can add the an ID to the element directly by accessing ._icon property:
// Create and save a reference to each marker
markers[person.id] = L.marker(person.latLng, {...}).addTo(map);
// Add the ID
markers[person.id]._icon.id = person.id;
Now when you handle click events, it's easy as pie to get that marker's ID:
$('.leaflet-marker-icon').on('click', function(e) {
// Use the event to find the clicked element
var el = $(e.srcElement || e.target),
id = el.attr('id');
alert('Here is the markers ID: ' + id + '. Use it as you wish.')
});
Option #3:
Another approach would be use the layerGroup interface. It provides a method, getLayer, that sounds like it would be perfect get our markers using an ID. However, at this time, Leaflet does not provide any way to specify a custom ID or name. This issue on Github discusses how this should be done. However you can get and save the auto-generated ID of any Marker (or iLayer for that matter) like so:
var group = L.layerGroup()
people.forEach(person => {
// ... create marker
group.addLayer( marker );
person.marker_id = group.getLayerId(marker)
})
Now that we have every marker's ID saved with each backing object in our array of data we can easily get the marker later on like so:
group.getLayer(person.marker_id)
See this pen for a full example...
Option #4:
The cleanest way to do this, if you have the time, would be to extend the leaflet's marker class to handle your individual needs cleanly. You could either add an id to the options or insert custom HTML into the marker that has your id/class. See the documentation for more info on this.
You can also you use the circleMarker which, in the path options, you will see has an option for className which can be nice for styling groups of similar markers.
Styling:
Almost forgot that your original question was posed for the purpose of styling... simply use the ID to access individual elements:
.leaflet-marker-icon#2342fc7 { ... }
Conclusion
I'll also mention that layer and feature groups provide another great way to interface with markers. Here is a question that discusses this a bit. Feel free to tinker with, or fork either the first or second pen and comment if I've missed something.

An easy way to do this is to add all the markers to a list with a unique id.
var markersObject = {};
markersObject["id1"] = marker1;
markersObject["id2"] = marker2;
markersObject["id3"] = marker3;
If the list of restaurants have a property in the html element of a single restaurant that corresponds to the id of the added marker. Something like:
Click
Then add the click event where you will pass the id of the restaurant (in this case "data-restaurantID") and do something like:
markersObject["passedValueFromTheClickedElement"].openPopup();
This way once you click on the item in the list a markers popup will open indicating where on the map is the restaurant located.

var MarkerIcon = L.Icon.extend({
options: {
customId: "",
shadowUrl: 'leaf-shadow.png',
iconSize: [64, 64],
shadowSize: [50, 64],
iconAnchor: [22, 94],
shadowAnchor: [4, 62],
popupAnchor: [-3, -76]
}
});
var greenIcon = new MarkerIcon({iconUrl: "/resources/images/marker-green.png"}),
redIcon = new MarkerIcon({iconUrl: "/resources/images/marker-red.png"}),
orangeIcon = new MarkerIcon({iconUrl: "/resources/images/marker-orange.png"});
var mymap = L.map('mapid').setView([55.7522200, 37.6155600], 13);
L.tileLayer('https://api.tiles.mapbox.com/v4/{id}/{z}/{x}/{y}.png?access_token=pk.eyJ1IjoibWFwYm94IiwiYSI6ImNpejY4NXVycTA2emYycXBndHRqcmZ3N3gifQ.rJcFIG214AriISLbB6B5aw', {
maxZoom: 18,
id: 'mapbox.streets'
}).addTo(mymap);
// добавить маркер
L.marker([55.7522200, 37.6155600], {customId:"010000006148", icon: greenIcon, title:setMarkerTitle("010000006148")}).addTo(mymap).on('click', markerOnClick);
L.marker([55.7622200, 37.6155600], {customId:"010053166625", icon: redIcon, title: setMarkerTitle("010053166625")}).addTo(mymap).on('click', markerOnClick);
function markerOnClick(e) {
var customId = this.options.customId;
document.location.href = "/view/abonents/" + customId;
}
function setMarkerTitle(customId){
var result = customId;
result += "\nline2 ";
result += "\nline3 ";
return result;
}

For my case, I found the best way was to generate and pass a unique ID to L.marker's Options object when I create it.
const newMarker = L.marker([lat, lng], { uniqueID })
You can then add this marker to a leaflet layerGroup.
const newLayerGroup = L.layerGroup().addTo(map);
newLayerGroup.addLayer(newMarker);
You can access the ID with layer.options.uniqueID This allows me to find and manipulate the marker later; all I need is Leaflet's .eachLayer() and the uniqueID.
My backend (Cloud Firestore) already generates unique document ID's, which makes it super easy to sync my Leaflet map and backend in real-time, rather than rebuilding and remounting the entire layerGroup or refreshing the page.
//e.g. a callback which fires whenever a doc has been removed from my db
newLayerGroup.eachLayer((layer) => {
if (deletedDocID === layer.options.uniqueID) {
newLayerGroup.removeLayer(layer);
}
});

I just added an ID to the extended control that got created, by using setAttribute.
Here is an example:
var someViewer = L.Control.extend({
onAdd: function () {
var someContainer = L.DomUtil.create('div');
var someDiv = L.DomUtil.create('div');
someDiv.setAttribute('id', 'SPQR_Gauge'); // <-- Just add this line to get an ID
// code continues down ...
After that, you can use pretty much anything. Style, innerHTML, you name it.
document.getElementbyId('someDiv').style = // bla bla bla

My solution is storing ID in e.target.options
function mark_click(e){
console.log(`${e.target.options.id} has been click`);
}
for (var i in data) {
var row = data[i];
var marker = L.marker([row.lat, row.lng], {
opacity: 1,
icon: myIcon,
id:123
});
marker.addTo(mymap).on('click', mark_click);
}

Leaflet's className option can allow one to add identifiers to objects:
var onMouseover = function() {
// returns all members of the specified class
d3.selectAll(".mySpecialClass")
.style("opacity", ".1");
};
// add desired class to pointer
L.circleMarker([46.85, 2.35], {className: "mySpecialClass"})
.addTo(map).on('mouseover', onMouseover);
// to select the marker(s) with a particular class, just use css selectors
// here's a d3.js solution
d3.selectAll(".mySpecialClass")
.style("opacity", ".3")

A fairly straight forward and easy way to accomplish creating an array of clickable markers within a leaflet map object is to manipulate the class list of the created marker by adding a custom incremented class name to each marker. Then it is easy to create a listener and know which marker was clicked. By skipping the active one or not, each has a retrievable click event with a reliable ID.
// creates markers, each with a leaflet supplied class
if (length === 1) {
for (i = 0; i < parks.length; ++i) {
if (parks[i].parksNumber !== parks.parksNumber)
L.marker([parks[i].latitude, parks[i].longitude], {
icon: parks[i].iconMarker
}).addTo(mymap);
}
}
// select all of the leaflet supplied class
let markers = document.querySelectorAll(".leaflet-marker-icon");
// loop through those elements and first assign the indexed custom class
for (i = 0; i < markers.length; ++i) {
markers[i].classList.add("marker_" + parks[i].parksNumber);
// then add a click listener to each one
markers[i].addEventListener("click", e => {
// pull the class list
let id = String(e.target.classList);
// pull your unique ID from the list, be careful cause this list could
// change orientation, if so loop through and find it
let parksNumber = id.split(" ");
parksNumber = parksNumber[parksNumber.length - 1].replace("marker_", "");
// you have your unique identifier to then do what you want with
search_Number_input.value = parksNumber;
HandleSearch();
});
}

1.) Lets create Marker with unique id...
L.marker([marker.lat, marker.lng],{customID:'some ID',title:marker.title}).on('click', this.markerClick).addTo(mymap);
2.) Go to node_modules#types\leaflet\index.d.ts and add customID?:string;
export interface MarkerOptions extends InteractiveLayerOptions {
icon?: Icon | DivIcon;
title?: string;
....
autoPanSpeed?: number;
customID:string;
}
3.) In the same file add customID to LeafletMouseEvent
export interface LeafletMouseEvent extends LeafletEvent {
latlng: LatLng;
layerPoint: Point;
containerPoint: Point;
originalEvent: MouseEvent;
customID:customID
}
4.) Create customID class
export class customID {
constructor(customID: string);
customID: number;
}
5.) Get your marker id in function
markerClick(e){
console.log(e.sourceTarget.options.customID)
}

How to display markers (huge numbers) on a map which has been logically divided into segments?

What i have done so far:
i'm developing an application where i have to display more than(50K) points/Markers on the Navteq map divided into different segments.
for example: if i have 50K points i will divide all points into different segments.
if i divide 50K points into 50 segments each segment would have 1000 points (may not be 50 segments , it may depend).
right now it is working but it takes long time and hangs to render all the points on the MAP.so that i would like to perform segmentation displaying to display only few points with clustering.
so that i can get an idea of how the segment will look like.
but the problem here is i should only perform the clustering based on the segments.otherwise points from different segments willbe mixed together and displayed
as single unit and that conveys the wrong information to the user.
so here my question is: is it possible to perform the clustering based on the segment. so that only points from same segment will be clustered.
Note: if this is not possible, i would like to use Latest version of here-maps 2.5.3 (Asynchronous) may reduce some time while loading, so that i would like to use indexing functionality also while rendering the points
to improve the rendering time using nokia.maps.clustering.Index class.
i studied that indexing would reduce the time while rendering the points/markers on map. does it help in my case? could anybody please suggest how to perform indexing ?
This is the code with which i'm displaying points on map:
function displayAllLightPoints(arrLightPointCoordinats, totalLightPoints,
selectedSegmentId, totalSegmentsCount,segmentColorcode)
{
var MyTheme1 = function () {
};
segmentColorcode = segmentColorcode.substring(2,segmentColorcode.length-1);
MyTheme1.prototype.getNoisePresentation = function (dataPoint) {
var markerLightPoint = new nokia.maps.map.Marker(dataPoint, {
icon: new nokia.maps.gfx.BitmapImage("..//Images//Lightpoint//" +
segmentColorcode + ".png"),
anchor: {
x: 12,
y: 12
}
});
return markerLightPoint;
};
MyTheme1.prototype.getClusterPresentation = function (data) {
var markerLightPoint = new
nokia.maps.map.StandardMarker(data.getBounds().getCenter(), {
icon: new nokia.maps.gfx.BitmapImage("..//Images//
Segment/" + segmentColorcode + ".png", null, 66, 65),
text: data.getSize(),
zIndex: 2,
anchor: {
x: 12,
y: 12
}
});
return markerLightPoint;
};
var ClusterProvider = nokia.maps.clustering.ClusterProvider,
theme = new MyTheme1(),
clusterProvider = new ClusterProvider(map, {
eps: 0.00000000001,
minPts: 1000000,
strategy: nokia.maps.clustering.ClusterProvider.
STRATEGY_DENSITY_BASED,
theme: theme,
dataPoints: []
});
var lightpointsDataSet1 = new Array();
for (var i = 0; i < totalLightPoints; i++) {
lightpointsDataSet1[i] = { latitude: arrLightPointCoordinats[i][0],
longitude: arrLightPointCoordinats[i][1], title:
'LightPoint ' + (i + 1) };
}
clusterProvider.addAll(lightpointsDataSet1);
clusterProvider.cluster();
}

To deal with a very large (50K+) data set , I would do all the heavy number crunching server side and send over a new JSON response whenever the map is updated. Something like the HTML page described here
The key section of the code is the ZoomObserver:
var zoomObserver = function (obj, key, newValue, oldValue) {
zoom = newValue;
if (zoom < 7)
{ zoom = 7;}
if (zoom > 16)
{ zoom = 16;}
// Define the XML filename to read that contains the marker data
placeMarkersOnMaps('http://api.maps.nokia.com/downloads/java-me/cluster/'+ zoom + '.xml'
+ '?lat1=' + map.getViewBounds().topLeft.latitude
+ '&lng1='+ map.getViewBounds().topLeft.longitude
+ '&lat2='+ map.getViewBounds().bottomRight.latitude
+ '&lng2='+ map.getViewBounds().bottomRight.longitude);
};
map.addObserver("zoomLevel", zoomObserver );
Where the REST service returns a "well-known" data format which can be used to add markers and clusters to the map.
Now assuming you have two massive data sets you could make two requests to different endpoints, or somehow distinguish which cluster of data belongs to which so that you would just be returning information of the form:
{latitude':51.761,'longitude':14.33128,'value':102091},
i.e. using the DataPoint standard (which means you could use a heat map as well.
Of course, what I'm not showing here is the back-end functionality to cluster in the first place - but this leaves the client (and the API) to do what it does best displaying data, not number crunching.