I have a standard leaflet map showing a tile layer. Now leaflet only lets you use panTo method using LatLng for example,
map.panTo(new L.LatLng(40.17, -98.12));
How will I use above panTo method if my coordinates are in EPSG:3857 for example (3679364.68,-9096106.74) ?
This is quite simple to to in Openlayers as once you define a map projection everything works in that projection. But Leaflet always works on latlng on the outside.
Any simple way to accomplish this using leaflet library?
Thanks!
Leaflet lets you use panTo method by unproject 3857 point. If you don't want to use proj4js library it also achieve in leaflet.
var point = new L.Point(3679364.68,-9096106.74); // Lon/Lat
var earthRadius = 6378137;
var latlng = L.Projection.SphericalMercator.unproject(point.divideBy(earthRadius));
map.panTo(new L.LatLng(latlng.lat, latlng.lng));
I can get it working if I use proj4js library to transform the coordinates by doing this:
var source = new Proj4js.Proj('EPSG:3857');
var dest = new Proj4js.Proj('EPSG:4326');
var p = new Proj4js.Point(-9096106.74,3679364.68); //this takes x,y
Proj4js.transform(source, dest, p);
this.map.setView(new L.LatLng(p.y, p.x),zoom);
But this is still not an ideal solution as it taxes me a Megabyte for for including the library. I am still looking for a leaflet solution. Knowing that internally leaflet already uses EPSG:3857 to fetch tiles, this shouldn't be this difficult.
Update
To do this purely in Leaflet, look at #ARsl's answer. Only reason I still accept this as my answer because, still feel uncomfortable doing the projection calculations like that (not that they are wrong), and just for that reason I don't accept this answer. Plus proj4js as added advantages of supporting many more datums.
I also haven't found any built-in method to convert EPSG:3857 coordinates to LatLng.
LeafLet crs class L.CRS.EPSG3857 has only project method which converts L.LatLng to L.Point in EPSG:3857 coordinates.
https://github.com/Leaflet/Leaflet/blob/master/src/geo/crs/CRS.EPSG3857.js
But it is quite easy to extend it with unproject method:
L.CRS.EPSG3857.unproject = function (point) { // Point -> LatLng
var earthRadius = 6378137;
projectionPoint = L.point(point).divideBy(earthRadius);
return this.projection.unproject(projectionPoint);
};
Then you can use it with panTo method:
map.panTo(map.options.crs.unproject([1372720.6476878107, 5690559.995203462]));
or:
map.panTo(L.CRS.EPSG3857.unproject([1372720.6476878107, 5690559.995203462]));
Related
I've ran across all fitbounds tutorials for Mapbox and still cannot figure out how refocus my map on a given raster layer. I have a menu that toggles a number of older maps and would like to refit the map at each turn.
Here's what I have so far. mapnumber is the string for my raster map.
var coordinates = map.getBounds(mapnumber);
var bounds = new mapboxgl.LngLatBounds(coordinates[0], coordinates[0]);
map.fitBounds({bounds});
The bounds are there, I just cannot use fitbounds on them. This is the error.
lng_lat.js:97 Uncaught Error: `LngLatLike` argument must be specified
as a LngLat instance, an object {lng: <lng>, lat: <lat>}, or an array
of [<lng>, <lat>]
Uncaught Error: LngLatLike argument must be specified
as a LngLat instance
It looks like you're using mapboxgl.LngLatBounds incorrectly. You'll need to pass in two LngLat instances, rather than two coordinates. The API docs have an example that creates a point for the southwest and northeast corners of your bounding box:
var sw = new mapboxgl.LngLat(-73.9876, 40.7661);
var ne = new mapboxgl.LngLat(-73.9397, 40.8002);
var llb = new mapboxgl.LngLatBounds(sw, ne);
Then you can use map.fitBounds() with the bounding box
map.fitBounds(llb);
UPDATE: answering follow up question
how can I extract the two sets (sw and ne) from the raster?
You can use the map.getSource() method. Pass in the source ID of your raster layer and that will return an object that has a bounds property. Use this bounds property to pass into map.fitBounds().
var bounds = map.getSource('mapbox://username.source-id').bounds;
map.fitBounds(bounds);
Here's a working example: https://codepen.io/mapsam/pen/RZvyBQ
I'm here because I'm trying to create a GTA V map with Leafletjs API. In deed, I've got my tiles that are ready. But the aim is to put markers on the map by using GTA V in-game coordinates. To achieve it, I need to convert the coordinates to LatLong but after many researches, I can't find a solution.
Example :
Thanks in advance.
Your coordinates are coming from different map projections. The Leaflet ones are most probably standard WGS 84 (SRID 4326). GTA V coordinates are obviously based on a different projection.
Coordinates can be transformed from one projection to anothers. But you need to know, which projection your coordinates are coming from, to do the math.
Here is an online converter provided with some common projections, and i tried your coordinates, but had no luck in coming close with these projections.
I tried this:
var latlng = new L.latLng(-43.1731, 6.6906);
var point = L.Projection.Mercator.project(latlng);
console.log(point);
// o.Point {x: 744794.1851014761, y: -5309112.129212381}
It is not close to your GTA V coordinates, but I'm not sure it were just for example.
You can use L.latlng function
http://leafletjs.com/reference.html#latlng
I have a list of lat long pairs. (Or I could create GeoJSON). I want to map them all on leaflet map.
How do I find what should I set as the center and as the zoom level so that all the points show up.
All the leaflet examples seem to use a fixed center and zoom, but I am accepting user input so I need to calculate them.
The easiest way is with a LatLngBounds object. You can then have the map fitBounds. Or get its center manually if you prefer.
var myPoints = [[1,1],[2,2] /*, ...*/ ];
var myBounds = new L.LatLngBounds(myPoints);
myMap.fitBounds(myBounds); //Centers and zooms the map around the bounds
You can even forgo instantiating the bounds object if you would like:
myMap.fitBounds([[1,1],[2,2] /*, ...*/ ]);
I'd recommend to use GeoJSON and create your leaflet map as described in the tutorial. Than you can simply use geojsonLayer.getBounds() together with map.setBounds() to zoom to your data.
I am getting line latitude & longitude as
LINESTRING(1491215.4689647 6893983.2031826,1494163.0718675 6894785.7919795)
after seeing this solution.
how to get points return from OpenLayers.Control.DrawFeature
Now what I want to do is that I want to display start point & end point on my web page.
So how can I extract latitude & longitude from here so that I can show it in my page.
If your linestring is already in OpenLayers, there is no reason to convert it to WKT. Linestring geometry contains array of Points. You can access components of geometry in several ways, for example:
drawControls[key].events.register('featureadded', drawControls[key], function(f) {
// First point
var firstPointGeom = f.feature.geometry.components[0].clone();
// Last point
var secondPointGeom = f.feature.geometry.components[f.feature.geometry.components.length - 1].clone();
// Now you got geometries, let's create features from them...
var firstPointFeat = new OpenLayers.Feature.Vector(firstPointGeom);
var secondPointGeom = new OpenLayers.Feature.Vector(secondPointGeom);
yourVectorLayer.addFeatures([firstPointFeat, secondPointGeom]);
});
Pay attention - this works with LineStrings. Probably it's not necessary to go into detail about clone(), it's up to particular use case, whether you need it, or you can use just var firstPointGeom = f.feature.geometry.components[0];
Thats WKT format, you're looking at. You'll potentially need to reproject those coordinates to the target projection if they are not in the same projection. After than, you should be able ot ask openlayers for the points of any given geometry using the base geometry functionaily. Get the point array from the linestring instance and iterate over it. Make sure you know the right coordinate order for your projection / data model.
Hope that helps!
I want to zoom to a particular house in the google mapS, but when I provide its bounds and lattitude and longitude, it does not show images as well as the particular house. Can anyone provide the solution for this?
Solution would be probably to transporm coordinates first. Unfortunately when You pass coordinates to OpanLayers.LonLat(lon,lat) it is supposed to be WGS:84, while OpenLayer.Bounds() needs coordinates given in EPSG:900913.
You should then use Proj4js.transform and pass transformed coordintes in EPSG:900913
You can transform it like this one:
var map = new OpenLayers.Map('map');
var location.transform(map.getProjectionObject(), new OpenLayers.Projection("EPSG:900913"));