README.md

Extended Geographic Projections

airy	aitoff	albers *	albersUsa *
armadillo	august	azimuthalEqualArea *	azimuthalEquidistant *
baker	berghaus	boggs	bonne
bromley	chamberlin	collignon	conicEqualArea *
conicConformal *	conicEquidistant *	craig	craster
cylindricalEqualArea	cylindricalStereographic	eckert1	eckert2
eckert3	eckert4	eckert5	eckert6
eisenlohr	equirectangular *	fahey	gilbert
ginzburg4	ginzburg5	ginzburg6	ginzburg8
ginzburg9	gnomonic *	gringorten	guyou
hammer	hammerRetroazimuthal	healpix	hill
homolosine	kavrayskiy7	lagrange	larrivee
laskowski	littrow	loximuthal	mercator *
miller	modifiedStereographic	mollweide	mtFlatPolarParabolic
mtFlatPolarQuartic	mtFlatPolarSinusoidal	naturalEarth	nellHammer
orthographic *	peirceQuincuncial	polyconic	polyhedron.butterfly
polyhedron.waterman	rectangularPolyconic	robinson	satellite
sinuMollweide	sinusoidal	stereographic *	times
twoPointAzimuthal	twoPointEquidistant	transverseMercator *	vanDerGrinten
vanDerGrinten2	vanDerGrinten3	vanDerGrinten4	wagner4
wagner6	wagner7	wiechel	winkel3

Projections:

• aitoff - Aitoff
• airy - Airy’s minimum-error azimuthal
• albers - Albers equal-area conic
• armadillo - Armadillo
• august - August conformal
• azimuthalEqualArea - Lambert azimuthal equal-area
• azimuthalEquidistant - azimuthal equidistant
• baker - Baker Dinomic
• berghaus - Berghaus Star
• boggs - Boggs eumorphic
• bonne - Bonne
• bromley - Bromley
• chamberlin - Chamberlin trimetric
• collignon - Collignon
• conicConformal - Lambert conformal conic
• conicEquidistant - conic equidistant
• craig - Craig retroazimuthal
• craster - Craster parabolic
• cylindricalEqualArea - cylindrical equal-area, Gall–Peters, Hobo–Dyer, Tobler world-in-a-square
• cylindricalStereographic - cylindrical stereographic, Gall’s stereographic
• eckert1 - Eckert I
• eckert2 - Eckert II
• eckert3 - Eckert III
• eckert4 - Eckert IV
• eckert5 - Eckert V
• eckert6 - Eckert VI
• eisenlohr - Eisenlohr conformal
• equirectangular - Equirectangular (Plate Carrée), Cassini
• fahey - Fahey
• foucaut - Foucaut
• gilbert - Gilbert’s two-world perspective (Note: this wraps a projection such as d3.geo.orthographic.)
• ginzburg4 - Ginzburg IV
• ginzburg5 - Ginzburg V
• ginzburg6 - Ginzburg VI
• ginzburg8 - Ginzburg VIII
• ginzburg9 - Ginzburg IX
• gnomonic - gnomonic
• gringorten - Gringorten
• guyou - Guyou hemisphere-in-a-square
• hammer - Hammer, Eckert–Greifendorff, quartic authalic, Briesemeister
• hammerRetroazimuthal - Hammer retroazimuthal
• healpix - HEALPix
• hill - Hill eucyclic, Maurer No. 73
• homolosine - Goode homolosine
• kavrayskiy7 - Kavrayskiy VII
• lagrange - Lagrange conformal
• larrivee - Larrivée
• laskowski - Laskowski tri-optimal
• littrow - Littrow
• loximuthal - loximuthal
• mercator - Mercator
• miller - Miller
• modifiedStereographic - modified stereographic
• mollweide - Mollweide, Atlantis
• mtFlatPolarParabolic - McBryde–Thomas flat-polar parabolic
• mtFlatPolarQuartic - McBryde–Thomas flat-polar quartic
• mtFlatPolarSinusoidal - McBryde–Thomas flat-polar sinusoidal
• naturalEarth - Natural Earth
• nellHammer - Nell–Hammer
• orthographic - orthographic
• peirceQuincuncial - Pierce quincuncial
• polyconic - polyconic
• rectangularPolyconic - rectangular polyconic
• robinson - Robinson
• satellite - satellite (tilted perpsective)
• sinusoidal - sinusoidal
• sinuMollweide - Sinu-Mollweide
• stereographic - stereographic
• times - Times
• transverseMercator - transverse Mercator
• twoPointAzimuthal - two-point azimuthal
• twoPointEquidistant - two-point equidistant
• vanDerGrinten - Van der Grinten
• vanDerGrinten2 - Van der Grinten II
• vanDerGrinten3 - Van der Grinten III
• vanDerGrinten4 - Van der Grinten IV
• wagner4 - Wagner IV, Putniṇš P2´
• wagner6 - Wagner VI
• wagner7 - Wagner VII
• wiechel - Wiechel
• winkel3 - Winkel tripel

This plugin also provides d3.geo.interrupt, which can be used to create arbitrary interrupted projections from a given raw projection. For example, see Philbrick’s interrupted Sinu-Mollweide.

This plugin requires D3 3.0 or greater. To use the official hosted version, include the projection plugin after including D3:

<script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script>
<script src="http://d3js.org/d3.geo.projection.v0.min.js" charset="utf-8"></script>

Alternatively, you can clone this repo, download the zipball, or right-click d3.geo.projection.v0.min.js and save.

To use this plugin within a Node.js context, you can npm install d3 d3-geo-projection and then say:

var d3 = require("d3");

require("d3-geo-projection")(d3);

Subsequently, d3.geo will contain all the extended projections.

Defining a New Projection

First define your raw projection function:

function cosinusoidal(λ, φ) {
  return [λ * Math.sin(φ), φ];
}

cosinusoidal.invert = function(x, y) {
  return [x / Math.sin(y), y];
};

Then create a constructor using d3.geo.projection:

d3.geo.cosinusoidal = function() {
  return d3.geo.projection(cosinusoidal);
};

You can optionally expose the raw projection to facilitate composite projections:

(d3.geo.cosinusoidal = function() {
  return d3.geo.projection(cosinusoidal);
}).raw = cosinusoidal;