[GIS] Leaflet circle radius unit

leaflet

Leaflet circle has two radius properties: _mRadius, which is the radius in meter, and _radius. Is _radius in radians or what is the unit of it?

Best Answer

_radius can't be in radians, because radians are not units of lengths. It is, in fact, in pixels. This is how it is initialized:

this._point = this._map.latLngToLayerPoint(latlng);
this._radius = Math.max(this._point.x - pointLeft.x, 1);

The property is used for SVG / Canvas output in getPathString() function.

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[GIS] Leaflet snap circle draw to marker

Did you find a solution?

I've created a function which does this for me.

  function mapToPosition(position){
    lon = position.coords.longitude;
    lat = position.coords.latitude;

    var marker = new L.Marker([lat,lon],{title: "Not at the right spot? Drag me!"}).addTo(map);
    marker.dragging.enable();

    marker.on('dragend', function(e){
      var coords = e.target.getLatLng();
      var lat = coords.lat;
      var lon = coords.lng;
      map.panTo({lon:lon,lat:lat})
      map.removeLayer(cir);
      cir = L.circle([lat,lon],1000).addTo(map).bindPopup("Area within 1km of your point.");
    });

    cir = L.circle([lat,lon],1000).addTo(map);
  }

I hope that helps!

[GIS] Calculate radius from magnitude of earthquake on leaflet map

The question is, what is your radius trying to represent. I get the feeling you don't really know. Is it meant to be the distance at which you would physically feel the quake? That's hard to measure.

Is it the energy of the quake? Then you would want a scale that isn't just linear - because each +1 unit of magnitude is around 30x stronger than the previous.

Plus, I know that earthquakes don't pass through the same land material types at the same rate, so if you want to be picky, the "radius" wouldn't be circular anyway.

In short, if you're not trying to show a specific geological feature, then I'd say just go with what looks good!

Best Answer

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[GIS] Leaflet snap circle draw to marker

[GIS] Calculate radius from magnitude of earthquake on leaflet map

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