D3

Spherical shapes ​

These shape generators return spherical GeoJSON for use with geoPath.

TIP

To generate a great arc (a segment of a great circle), pass a GeoJSON LineString geometry object to a geoPath. D3’s projections use geodesic interpolation for intermediate points.

geoGraticule() ​

Source · Constructs a geometry generator for creating graticules: a uniform grid of meridians and parallels for showing projection distortion. The default graticule has meridians and parallels every 10° between ±80° latitude; for the polar regions, there are meridians every 90°.

graticule() ​

Source · Returns a GeoJSON MultiLineString geometry object representing all meridians and parallels for this graticule.

graticule.lines() ​

Source · Returns an array of GeoJSON LineString geometry objects, one for each meridian or parallel for this graticule.

graticule.outline() ​

Source · Returns a GeoJSON Polygon geometry object representing the outline of this graticule, i.e. along the meridians and parallels defining its extent.

graticule.extent(extent) ​

Source · If extent is specified, sets the major and minor extents of this graticule. If extent is not specified, returns the current minor extent, which defaults to ⟨⟨-180°, -80° - ε⟩, ⟨180°, 80° + ε⟩⟩.

graticule.extentMajor(extent) ​

Source · If extent is specified, sets the major extent of this graticule. If extent is not specified, returns the current major extent, which defaults to ⟨⟨-180°, -90° + ε⟩, ⟨180°, 90° - ε⟩⟩.

graticule.extentMinor(extent) ​

Source · If extent is specified, sets the minor extent of this graticule. If extent is not specified, returns the current minor extent, which defaults to ⟨⟨-180°, -80° - ε⟩, ⟨180°, 80° + ε⟩⟩.

graticule.step(step) ​

Source · If step is specified, sets the major and minor step for this graticule. If step is not specified, returns the current minor step, which defaults to ⟨10°, 10°⟩.

graticule.stepMajor(step) ​

Source · If step is specified, sets the major step for this graticule. If step is not specified, returns the current major step, which defaults to ⟨90°, 360°⟩.

graticule.stepMinor(step) ​

Source · If step is specified, sets the minor step for this graticule. If step is not specified, returns the current minor step, which defaults to ⟨10°, 10°⟩.

graticule.precision(angle) ​

Source · If precision is specified, sets the precision for this graticule, in degrees. If precision is not specified, returns the current precision, which defaults to 2.5°.

geoGraticule10() ​

Source · A convenience method for directly generating the default 10° global graticule as a GeoJSON MultiLineString geometry object. Equivalent to:

js
function geoGraticule10() {
  return d3.geoGraticule()();
}

geoCircle() ​

Source · Returns a new circle generator.

circle(...arguments) ​

Source · Returns a new GeoJSON geometry object of type “Polygon” approximating a circle on the surface of a sphere, with the current center, radius and precision. Any arguments are passed to the accessors.

circle.center(center) ​

Source · If center is specified, sets the circle center to the specified point [longitude, latitude] in degrees, and returns this circle generator. The center may also be specified as a function; this function will be invoked whenever a circle is generated, being passed any arguments passed to the circle generator. If center is not specified, returns the current center accessor, which defaults to:

js
function center() {
  return [0, 0];
}

circle.radius(radius) ​

Source · If radius is specified, sets the circle radius to the specified angle in degrees, and returns this circle generator. The radius may also be specified as a function; this function will be invoked whenever a circle is generated, being passed any arguments passed to the circle generator. If radius is not specified, returns the current radius accessor, which defaults to:

js
function radius() {
  return 90;
}

circle.precision(angle) ​

Source · If precision is specified, sets the circle precision to the specified angle in degrees, and returns this circle generator. The precision may also be specified as a function; this function will be invoked whenever a circle is generated, being passed any arguments passed to the circle generator. If precision is not specified, returns the current precision accessor, which defaults to:

js
function precision() {
  return 2;
}

Small circles do not follow great arcs and thus the generated polygon is only an approximation. Specifying a smaller precision angle improves the accuracy of the approximate polygon, but also increase the cost to generate and render it.