I want to create a point B on the nearest lineString when I create another point A on the map. A and B are connected with a lineString which is perpendicular with the nearest lineString. I tried something but it's not working.. I search on Google for two hours but I didn't find a solution of my problem.. Someone can help me ?
For instance, it can be like this :
Example
Thanks,
Vico
You should be able to achieve this using the Turf library's nearestPointOnLine function. So if L is the LineString feature, and A is the newly created point, then you will have something like:
const B = turf.nearestPointOnLine(L, A)
const tangent = {
type: 'LineString',
coordinates: [A.geometry.coordinates, B.geometry.coordinates]
}
map.addSource({ type: 'geojson', id: 'tangent', tangent})
Related
I execute the following code in my leaflet webmap
map.getBounds().getWest() + "&y1=" +
map.getBounds().getSouth() + "&x2=" +
map.getBounds().getEast() + "&y2=" +
map.getBounds().getNorth()
This results in a result showing me four coordinates in the WGS84 (standard) coordinate system.
Is there any way to alter this so it will output 28992 coordinates instead?
I guess that by "28992 coordinates" you're referring to the EPSG:28992 Coordinate Reference System.
The canonical way to use "non-standard" CRSs in Leaflet is to leverage proj4leaflet. This answer assumes that you're already doing so.
So the getBounds() method of L.Map always returns a L.LatLngBounds instance, which refer to unprojected WGS84 coordinates. However, we can use the map's CRS to project a L.LatLng into a L.Point with the projected coordinates, in the map's display CRS; e.g.
var map = L.map('containerId`, { crs: crsForEpsg28992 });
var foo = map.options.crs.project(L.latLng([60.3,21.1]));
var qux = map.options.crs.project(map.getCenter());
Because of how map projections work (they rotate and bend the coordinate spaces), and because of how proj4js is implemented, it's not possible to project a bounding box into a bounding box. (In most cases, the projection of a bounding box would be a curved polygon!). This image from an article by Gregor Aisch illustrates the issue:
We can, however, do an approximation: project the four corners of the bounding box, e.g.:
var mapBounds = map.getBounds();
var crs = map.options.crs;
var nw = crs.project(mapBounds.getNorthWest());
var ne = crs.project(mapBounds.getNorthEast());
var sw = crs.project(mapBounds.getSouthWest());
var se = crs.project(mapBounds.getSouthEast());
We can even create a L.Bounds (but not a L.LatLngBounds!) from those projected coordinates; that'll be a bbox in the specified CRS that contains all corners, e.g.:
var bbox = L.bounds([nw, ne, sw, se]);
It's not gonna be perfect, but that approximation should be enough for most use cases.
See also this working example (based off on one of the proj4leaflet examples), which should further illustrate the issue.
I am working with Leaflet and Leaflet-Draw in Angular to draw some polygons on the Google Map. How can I implement a listener when the user clicks exactly on the edge of the drawn polygons and get the lat and lng of that edge. I know a similar situation can be implemented with Google Map API like the code below, but I can not find any source to help me implement the same thing in Leaflet.
google.maps.event.addListener(polygon, 'click', function (event) { console.log(event.edge) }
Google Map Documentation: https://developers.google.com/maps/documentation/javascript/reference/polygon#PolyMouseEvent
For those who come across this question: I found a solution myself!
I didn't find anything directly from Leaflet draw library that I could use, so I defined the problem for myself as a trigonometry problem and solve it that way.
I defined a function in which on polygon click, it converts the event.latlng and loops over polygon.getLatLngs()[0] taking a pair of A and B points. A is the first coordinates, B is the next and if it reaches to the end of array, B will be the first point. Then using Collinear Function of 3 points with x, y, I checked if the clicked x, y has a same slope as point A and B.(has to be rounded it up), if so, I would save that A and B point pair with their latLng information and further used it in my project.
Although this method works, I would appreciate if anybody would know a better solution or library built-in function that can be used instead. Thanks!
When the user clicks on the polygon you can loop through all corners and check if he clicked in the near of the corner.
poly.on('click', function(e){
var latlng = e.latlng;
var corners = poly.getLatLngs();
if(!L.LineUtil.isFlat(corners)){ //Convert to a flat array
corners = corners[0];
}
//Convert the point to pixels
var point = mymap.latLngToContainerPoint(latlng);
//Loop through each corner
corners.forEach(function(ll){
//Convert the point to pixels
var point1 = mymap.latLngToContainerPoint(ll);
var distance = Math.sqrt(Math.pow(point1.x - point.x, 2) + Math.pow(point.y - point1.y, 2));
//Check if distance between pixels is smaller then 10
if(distance < 10){
console.log('corner clicked');
}
});
});
This is plain JS you have to convert it self to angular.
A alternativ is to place on each corner a DivMarker or a CircleMarker and fire a event if the marker is clicked.
Looks like: https://geoman.io/leaflet-geoman
please could anyone help?
I need to use a map.toFly() method to interpolate between 2 locations.
According to the Mapbox documentation, I need to pass in an object describing the destination I want to fly to. The object has to have a center property holding an array with centre Long/lat coordinates of the destination I need to be taken to.
https://docs.mapbox.com/mapbox-gl-js/example/flyto/
My problem with implementing the method is that I only have bounding box coordinates of the 2 locations between which I need to interpolate . I can’t do something like this:
map.flyTo(bbox)
Does anyone know how to obtain
centre Long/lat coordinates of each location based on their bbox coordinates?
Assuming you have 2 LngLatBounds objects you can call the getCenter() method.
var point1 = bounds1.getCenter();
var point2 = bounds2.getCenter();
where both bounds1 and bounds2 are objects of the type LngLatBounds.
Check:
https://docs.mapbox.com/mapbox-gl-js/api/#lnglatbounds#getcenter
Edit: for the values you gave in your comment it would be for the first bounds:
var sw1 = new mapboxgl.LngLat(110.2672863, -7.1144639);
var ne1 = new mapboxgl.LngLat(110.5088836, -6.9319917);
var bounds1 = new mapboxgl.LngLatBounds(sw1, ne1);
Note: Mapbox GL uses longitude, latitude coordinate order (as opposed to latitude, longitude).
I am trying to display a certain amount of points within a specific range, that is within a circle. But when using the .getBounds() function for comparison to see whether the point is within the bound, i get some points outside it as shown in the screenshot below:
Map Screenshot
The code currently using to check if the point is within the circle bound is below:
echo '
var mark = L.marker([' . $r->coordinates[0]->longitude . ',' . $r->coordinates[0]->latitude . ']);
if(circle.getBounds().contains(mark.getLatLng())){
mark.addTo(map);
mark.bindPopup("'.$info.'");
}
';
I am looping into an array to retrieve the latitude and longitude and from there, to see whether the coordinates fills into the bound, if so, it adds it to the map with their corresponding popup
Any solution regarding this particular issue?
Thanks for helping
You can create your own contains method and add it to the L.Circle class because it doesn't have one by default. You can use the utility method distanceTo of the L.LatLng objects to calculate distance between your marker and the circle's center and compare that to the circle's radius:
L.Circle.include({
contains: function (latLng) {
return this.getLatLng().distanceTo(latLng) < this.getRadius();
}
});
Now when you have a circle and a marker or latlng object you can do this:
var map = L.map(...);
var circle = L.circle(...).addTo(map),
marker = L.marker(...).addTo(map);
latLng = L.latLng(...);
// Returns true when in the circle and false when outside
circle.contains(marker.getLatLng());
circle.contains(latLng);
Working example on Plunker: http://plnkr.co/edit/OPF7DM?p=preview
L.Circle reference: http://leafletjs.com/reference.html#circle
L.Marker reference: http://leafletjs.com/reference.html#marker
L.LatLng reference: http://leafletjs.com/reference.html#latlng
The method getBounds() always returns a rectangular area. Hence it can't be used for checking whether a non-rectangular object contains a given point.
For a circle you should be able to calculate the distance (distanceTo()) of the point to the circle's center (getLatLng()) and check whether it is smaller than the circle's radius (getRadius()). Note that the distance and radius are in meters.
Hey people this is going to be my first question so dont hit me too hard !
Before I have already added polygons but the intersection is a bit complicating.
with pre-defined i mean for example intersection coordinates of two other polygons. I'm calculating the area of the polygon intersection but i also want to highlight the area. Thanks
You would need two steps:
calculate intersection: polygon from 2 polygons. I would use JTS for it, you would need to provide data in JTS objects.
highlight the intersection on mapview (nutiteq for example). You can just add the resulting polygon as one geometry element into geometry layer, just as any other polygon. Use special styling to make it look different. You would need to convert JTS polygon to Nutiteq Polygon object to show it on map
ArrayList<MapPos> keslist = new ArrayList<MapPos>();
for (int i = 0; i < sonuc.getNumPoints(); i++) {
double lon = sonuc.getX(i);
double lat = sonuc.getY(i);
MapPos mPos = new MapPos(lon, lat);
keslist.add(mPos);
}
PolygonStyle polygonStyle = PolygonStyle.builder().setColor(Color.GREEN).build();
StyleSet<PolygonStyle> polygonStyleSet = new StyleSet<PolygonStyle>(null);
polygonStyleSet.setZoomStyle(10, polygonStyle);
Polygon KesisimPol = new Polygon(keslist, new DefaultLabel("Kesişim"), polygonStyleSet, null);
GeometryLayer geomLayer = new GeometryLayer(mapView.getLayers().getBaseLayer().getProjection());
mapView.getLayers().addLayer(geomLayer);
geomLayer.add(KesisimPol);
}
Here is my solution. I've tried it works. Right now I'm trying to add this new polygon to editable objects layer. Because I can't use the result polygon in another intersection process.
I hope this will help the others.