How can I find the area of a polygon in square km using D3.js? I'm not even really sure whether to use d3.geo.path.area or d3.geo.area.
Here is my code (JSFiddle):
var d = { "type":"Feature", "id":"7525", "properties":{"name":"Paris, 11e arrondissement","id":"117525"}, "geometry": { "type":"Polygon", "coordinates":[[[2.377,48.8719],[2.3991,48.8481],[2.369,48.8532], [2.3684,48.8557],[2.3639,48.8674],[2.377,48.8719]]] } }; var w=720, h=640; var projection = d3.geo.orthographic().scale(3660).rotate([-3,-46.35]) .clipExtent([[0,0], [w,h]]).translate([w/2,h/2]); var path = d3.geo.path().projection(projection); console.log('path area', path.area(d)); console.log('geo area', d3.geo.area(d)); For path area I get 1.0841410092907608 and for geo area I get 8.101249039703731e-8.
The docs suggest that the first is the result in pixels, and the second is the result in steradians. Is it possible to convert steradians to square km?
أكثر...
Here is my code (JSFiddle):
var d = { "type":"Feature", "id":"7525", "properties":{"name":"Paris, 11e arrondissement","id":"117525"}, "geometry": { "type":"Polygon", "coordinates":[[[2.377,48.8719],[2.3991,48.8481],[2.369,48.8532], [2.3684,48.8557],[2.3639,48.8674],[2.377,48.8719]]] } }; var w=720, h=640; var projection = d3.geo.orthographic().scale(3660).rotate([-3,-46.35]) .clipExtent([[0,0], [w,h]]).translate([w/2,h/2]); var path = d3.geo.path().projection(projection); console.log('path area', path.area(d)); console.log('geo area', d3.geo.area(d)); For path area I get 1.0841410092907608 and for geo area I get 8.101249039703731e-8.
The docs suggest that the first is the result in pixels, and the second is the result in steradians. Is it possible to convert steradians to square km?
أكثر...