d3-geo-projection

Extended geographic projections for d3-geo. See Command-Line Cartography for an introduction.

Installing

If you use NPM, npm install d3-geo-projection. Otherwise, download the latest release. You can also load directly from d3js.org as a standalone library. AMD, CommonJS, and vanilla environments are supported. In vanilla, a d3 global is exported:

<script src="https://d3js.org/d3-array.v1.min.js"></script>
<script src="https://d3js.org/d3-geo.v1.min.js"></script>
<script src="https://d3js.org/d3-geo-projection.v2.min.js"></script>
<script>

var aitoff = d3.geoAitoff();

</script>

Try d3-geo-projection in your browser.

API Reference

• Projections
• Interrupted Projections
• Polyhedral Projections
• Quincuncial Projections
• Transformations

Projections

Note: projections tagged [d3-geo] are exported by d3-geo, not d3-geo-projection. These commonly-used projections are also included in the d3 default bundle.

d3.geoAiry() Source
d3.geoAiryRaw(beta)

Airy’s minimum-error azimuthal projection.

airy.radius([radius])

Defaults to 90°.

d3.geoAitoff() Source
d3.geoAitoffRaw

The Aitoff projection.

d3.geoAlbers() Source [d3-geo]

Albers’ equal-area conic projection.

d3.geoArmadillo() Source
d3.geoArmadilloRaw(phi0)

The armadillo projection. The default center assumes the default parallel of 20° and should be changed if a different parallel is used. Note: requires clipping to the sphere.

armadillo.parallel([parallel])

Defaults to 20°.

d3.geoAugust() Source
d3.geoAugustRaw

August’s epicycloidal conformal projection.

d3.geoAzimuthalEqualArea() Source [d3-geo]
d3.geoAzimuthalEqualAreaRaw

The Lambert azimuthal equal-area projection.

d3.geoAzimuthalEquidistant() Source [d3-geo]
d3.geoAzimuthalEquidistantRaw

The azimuthal equidistant projection.

d3.geoBaker() Source
d3.geoBakerRaw

The Baker Dinomic projection.

d3.geoBerghaus() Source
d3.geoBerghausRaw(lobes)

Berghaus’ star projection. The default center assumes the default lobe number of 5 and should be changed if a different number of lobes is used. Note: requires clipping to the sphere.

berghaus.lobes([lobes]) Source

If lobes is specified, sets the number of lobes in the resulting star, and returns this projection. If lobes is not specified, returns the current lobe number, which defaults to 5.

d3.geoBertin1953() Source
d3.geoBertin1953Raw

Jacques Bertin’s 1953 projection.

d3.geoBoggs() Source
d3.geoBoggsRaw

The Boggs eumorphic projection. More commonly used in interrupted form.

d3.geoBonne() Source
d3.geoBonneRaw(phi0)

The Bonne pseudoconical equal-area projection. The Werner projection is a limiting form of the Bonne projection with a standard parallel at ±90°. The default center assumes the default parallel of 45° and should be changed if a different parallel is used.

bonne.parallel([parallel])

Defaults to 45°.

d3.geoBottomley() Source
d3.geoBottomleyRaw(sinPsi)

The Bottomley projection “draws lines of latitude as concentric circular arcs, with arc lengths equal to their lengths on the globe, and placed symmetrically and equally spaced across the vertical central meridian.”

bottomley.fraction([fraction])

Defaults to 0.5, corresponding to a sin(ψ) where ψ = π/6.

d3.geoBromley() Source
d3.geoBromleyRaw

The Bromley projection is a rescaled Mollweide projection.

d3.geoChamberlin(point0, point1, point2) Source
d3.geoChamberlinRaw(p0, p1, p2)

The Chamberlin trimetric projection. This method does not support projection.rotate: the three reference points implicitly determine a fixed rotation.

d3.geoChamberlinAfrica() Source

The Chamberlin projection for Africa using points [0°, 22°], [45°, 22°], [22.5°, -22°].

d3.geoCollignon() Source
d3.geoCollignonRaw

The Collignon equal-area pseudocylindrical projection. This projection is used in the polar areas of the HEALPix projection.

d3.geoConicConformal() Source [d3-geo]
d3.geoConicConformalRaw

The Lambert conformal conic projection.

d3.geoConicEqualArea() Source [d3-geo]
d3.geoConicEqualAreaRaw

Albers’ conic equal-area projection.

d3.geoConicEquidistant() Source [d3-geo]
d3.geoConicEquidistantRaw

The conic equidistant projection.

d3.geoCraig() Source
d3.geoCraigRaw(phi)

The Craig retroazimuthal projection. Note: this projection tends to fold over itself if the standard parallel is non-zero; we have not yet implemented the necessary advanced clipping to avoid overlap.

craig.parallel([parallel])

Defaults to 0°.

d3.geoCraster() Source
d3.geoCrasterRaw

The Craster parabolic projection; also known as Putniņš P4.

d3.geoCylindricalEqualArea() Source
d3.geoCylindricalEqualAreaRaw(phi0)

The cylindrical equal-area projection. Depending on the chosen parallel, this projection is also known as the Lambert cylindrical equal-area (0°), Gall–Peters (45°), Hobo–Dyer (37.5°), and Tobler world-in-a-square (~55.654°).

cylindricalEqualArea.parallel([parallel])

Defaults to approximately 38.58°, fitting the world in a 960×500 rectangle.

d3.geoCylindricalStereographic() Source
d3.geoCylindricalStereographicRaw(phi0)

The cylindrical stereographic projection. Depending on the chosen parallel, this projection is also known as Braun’s stereographic (0°) and Gall’s stereographic (45°).

cylindricalStereographic.parallel([parallel])

Defaults to 0°.

d3.geoEckert1() Source
d3.geoEckert1Raw

The Eckert I projection.

d3.geoEckert2() Source
d3.geoEckert2Raw

The Eckert II projection.

d3.geoEckert3() Source
d3.geoEckert3Raw

The Eckert III projection.

d3.geoEckert4() Source
d3.geoEckert4Raw

The Eckert IV projection.

d3.geoEckert5() Source
d3.geoEckert5Raw

The Eckert V projection.

d3.geoEckert6() Source
d3.geoEckert6Raw

The Eckert VI projection.

d3.geoEisenlohr() Source
d3.geoEisenlohrRaw(lambda, phi)

The Eisenlohr conformal projection.

d3.geoEquirectangular() Source [d3-geo]
d3.geoEquirectangularRaw

The equirectangular (plate carrée) projection. The Cassini projection is the transverse aspect of the equirectangular projection.

d3.geoFahey() Source
d3.geoFaheyRaw

The Fahey pseudocylindrical projection.

d3.geoFoucaut() Source
d3.geoFoucautRaw

Foucaut’s stereographic equivalent projection.

d3.geoGilbert([type]) Source

Gilbert’s two-world perspective projection. Wraps an instance of the specified projection type; if not specified, defaults to d3.geoOrthographic.

d3.geoGingery() Source
d3.geoGingeryRaw(rho, lobes)

The U.S.-centric Gingery world projection, as inspired by Cram’s Air Age. Note: requires clipping to the sphere.

gingery.radius([radius]) Source

Defaults to 30°.

gingery.lobes([lobes]) Source

Defaults to 6.

d3.geoGinzburg4() Source
d3.geoGinzburg4Raw

The Ginzburg IV projection.

d3.geoGinzburg5() Source
d3.geoGinzburg5Raw

The Ginzburg V projection.

d3.geoGinzburg6() Source
d3.geoGinzburg6Raw

The Ginzburg VI projection.

d3.geoGinzburg8() Source
d3.geoGinzburg8Raw

The Ginzburg VIII projection.

d3.geoGinzburg9() Source
d3.geoGinzburg9Raw

The Ginzburg IX projection.

d3.geoGnomonic() Source [d3-geo]
d3.geoGnomonicRaw

The gnomonic projection.

d3.geoGringorten() Source
d3.geoGringortenRaw

The Gringorten square equal-area projection, rearranged to give each hemisphere an entire square.

d3.geoGuyou() Source
d3.geoGuyouRaw

The Guyou hemisphere-in-a-square projection. Peirce is credited with its quincuncial form.

d3.geoHammer() Source
d3.geoHammerRaw(A, B)

The Hammer projection. Depending the chosen coefficient and aspect, also known as Eckert–Greifendorff, quartic authalic, and Briesemeister.

hammer.coefficient([coefficient]) Source

Defaults to 2.

d3.geoHammerRetroazimuthal() Source
d3.geoHammerRetroazimuthalRaw(phi0)

The Hammer retroazimuthal projection. Note: requires clipping to the sphere.

hammerRetroazimuthal.parallel([parallel])

Defaults to 45°.

d3.geoHealpix() Source
d3.geoHealpixRaw(lobes)

The HEALPix projection: a Hierarchical Equal Area isoLatitude Pixelisation of a 2-sphere. In this implementation, the parameter K is fixed at 3. Note: requires clipping to the sphere.

healpix.lobes([lobes])

If lobes is specified, sets the number of lobes (the parameter H in the literature) and returns this projection. If lobes is not specified, returns the current lobe number, which defaults to 4.

d3.geoHill() Source
d3.geoHillRaw(K)

Hill eucyclic projection is pseudoconic and equal-area.

hill.ratio([ratio])

Defaults to 1. With a ratio of 0, this projection becomes the Maurer No. 73. As it approaches ∞, the projection converges to the Eckert IV.

d3.geoHomolosine() Source
d3.geoHomolosineRaw

The pseudocylindrical, equal-area Goode homolosine projection is normally presented in interrupted form.

d3.geoHyperelliptical() Source
d3.geoHyperellipticalRaw

Waldo R. Tobler’s hyperelliptical is a family of equal-area pseudocylindrical projections. Parameters include k, the exponent of the superellipse (or Lamé curve) that defines the shape of the meridians (default k = 2.5); alpha, which governs the weight of the cylindrical projection that is averaged with the superellipse (default alpha = 0); and gamma, that shapes the aspect ratio (default: gamma = 1.183136).

d3.geoKavrayskiy7() Source
d3.geoKavrayskiy7Raw

The Kavrayskiy VII pseudocylindrical projection.

d3.geoLagrange() Source
d3.geoLagrangeRaw(n)

The Lagrange conformal projection.

lagrange.spacing([spacing])

Defaults to 0.5.

d3.geoLarrivee() Source
d3.geoLarriveeRaw

The Larrivée projection.

d3.geoLaskowski() Source
d3.geoLaskowskiRaw

The Laskowski tri-optimal projection simultaneously minimizes distance, angular, and areal distortion.

d3.geoLittrow() Source
d3.geoLittrowRaw

The Littrow projection is the only conformal retroazimuthal map projection. Typically clipped to the geographic extent [[-90°, -60°], [90°, 60°]].

d3.geoLoximuthal() Source
d3.geoLoximuthalRaw(phi0)

The loximuthal projection is “characterized by the fact that loxodromes (rhumb lines) from one chosen central point (the intersection of the central meridian and central latitude) are shown as straight lines, correct in azimuth from the center, and are ‘true to scale’… It is neither an equal-area projection nor conformal.”

loximuthal.parallel([parallel])

Defaults to 40°.

d3.geoMercator() Source [d3-geo]
d3.geoMercatorRaw

The spherical Mercator projection.

d3.geoMiller() Source
d3.geoMillerRaw

The Miller cylindrical projection is a modified Mercator projection.

d3.geoModifiedStereographic(coefficients, rotate) Source
d3.geoModifiedStereographicRaw(coefficients)

The family of modified stereographic projections. The default clip angle for these projections is 90°. These projections do not support projection.rotate: a fixed rotation is applied that is specific to the given coefficients.

d3.geoModifiedStereographicAlaska() Source

A modified stereographic projection for Alaska.

d3.geoModifiedStereographicGs48() Source

A modified stereographic projection for the conterminous United States.

d3.geoModifiedStereographicGs50() Source

A modified stereographic projection for the United States including Alaska and Hawaii. Typically clipped to the geographic extent [[-180°, 15°], [-50°, 75°]].

d3.geoModifiedStereographicMiller() Source

A modified stereographic projection for Europe and Africa. Typically clipped to the geographic extent [[-40°, -40°], [80°, 80°]].

d3.geoModifiedStereographicLee() Source

A modified stereographic projection for the Pacific ocean.

d3.geoMollweide() Source
d3.geoMollweideRaw

The equal-area, pseudocylindrical Mollweide projection. The oblique aspect is known as the Atlantis projection. Goode’s interrupted Mollweide is also widely known.

d3.geoMtFlatPolarParabolic() Source
d3.geoMtFlatPolarParabolicRaw

The McBryde–Thomas flat-polar parabolic pseudocylindrical equal-area projection.

d3.geoMtFlatPolarQuartic() Source
d3.geoMtFlatPolarQuarticRaw

The McBryde–Thomas flat-polar quartic pseudocylindrical equal-area projection.

d3.geoMtFlatPolarSinusoidal() Source
d3.geoMtFlatPolarSinusoidalRaw

The McBryde–Thomas flat-polar sinusoidal equal-area projection.

d3.geoNaturalEarth1() Source [d3-geo]
d3.geoNaturalEarth1Raw

The Natural Earth projection.

d3.geoNaturalEarth2() Source
d3.geoNaturalEarth2Raw

The Natural Earth II projection. Compared to Natural Earth, it is slightly taller and rounder.

d3.geoNellHammer() Source
d3.geoNellHammerRaw

The Nell–Hammer projection.

d3.geoOrthographic() Source [d3-geo]
d3.geoOrthographicRaw

The orthographic projection.

d3.geoPatterson() Source
d3.geoPattersonRaw

The Patterson cylindrical projection.

d3.geoPolyconic() Source
d3.geoPolyconicRaw

The American polyconic projection.

d3.geoRectangularPolyconic() Source
d3.geoRectangularPolyconicRaw(phi0)

The rectangular (War Office) polyconic projection.

rectangularPolyconic.parallel([parallel])

Defaults to 0°.

d3.geoRobinson() Source
d3.geoRobinsonRaw

The Robinson projection.

d3.geoSatellite() Source
d3.geoSatelliteRaw(P, omega)

The satellite (tilted perspective) projection.

satellite.tilt([tilt])

Defaults to 0°.

satellite.distance([distance])

Distance from the center of the sphere to the point of view, as a proportion of the sphere’s radius; defaults to 2.0. The recommended maximum clip angle for a given distance is acos(1 / distance) converted to degrees. If tilt is also applied, then more conservative clipping may be necessary. For exact clipping, the in-development geographic projection pipeline is needed; see the satellite example.

d3.geoSinusoidal() Source
d3.geoSinusoidalRaw

The sinusoidal projection.

d3.geoSinuMollweide() Source
d3.geoSinuMollweideRaw

Allen K. Philbrick’s Sinu-Mollweide projection. See also the interrupted form.

d3.geoStereographic() Source [d3-geo]
d3.geoStereographicRaw

The stereographic projection.

d3.geoTimes() Source
d3.geoTimesRaw

John Muir’s Times projection.

d3.geoTransverseMercator() Source [d3-geo]
d3.geoTransverseMercatorRaw

The transverse spherical Mercator projection.

d3.geoTwoPointAzimuthal(point0, point1) Source
d3.geoTwoPointAzimuthalRaw(d)

The two-point azimuthal projection “shows correct azimuths (but not distances) from either of two points to any other point. [It can] be used to locate a ship at sea, given the exact location of two radio transmitters and the direction of the ship to the transmitters.” This projection does not support projection.rotate, as the rotation is fixed by the two given points.

d3.geoTwoPointAzimuthalUsa() Source

The two-point azimuthal projection with points [-158°, 21.5°] and [-77°, 39°], approximately representing Honolulu, HI and Washington, D.C.

d3.geoTwoPointEquidistant(point0, point1) Source
d3.geoTwoPointEquidistantRaw(z0)

The two-point equidistant projection. This projection does not support projection.rotate, as the rotation is fixed by the two given points. Note: to show the whole Earth, this projection requires clipping to spherical polygons, which is not yet supported in D3. However, you can typically show most of the Earth by using D3’s great-circle clipping.

d3.geoTwoPointEquidistantUsa() Source

The two-point equidistant projection with points [-158°, 21.5°] and [-77°, 39°], approximately representing Honolulu, HI and Washington, D.C.

d3.geoVanDerGrinten() Source
d3.geoVanDerGrintenRaw

The Van der Grinten projection.

d3.geoVanDerGrinten2() Source
d3.geoVanDerGrinten2Raw

The Van der Grinten II projection.

d3.geoVanDerGrinten3() Source
d3.geoVanDerGrinten3Raw

The Van der Grinten III projection.

d3.geoVanDerGrinten4() Source
d3.geoVanDerGrinten4Raw

The Van der Grinten IV projection.

d3.geoWagner4() Source
d3.geoWagner4Raw

The Wagner IV projection, also known as Putniṇš P2´.

d3.geoWagner6() Source
d3.geoWagner6Raw

The Wagner VI projection.

d3.geoWagner7() Source
d3.geoWagner7Raw

The Wagner VII projection.

d3.geoWiechel() Source
d3.geoWiechelRaw

The Wiechel projection.

d3.geoWinkel3() Source
d3.geoWinkel3Raw

The Winkel tripel projection.

Interrupted Projections

d3.geoInterrupt(project, lobes) Source

Defines a new interrupted projection for the specified raw projection function project and the specified array of lobes. The array lobes contains two elements representing the hemilobes for the northern hemisphere and the southern hemisphere, respectively. Each hemilobe is an array of triangles, with each triangle represented as three points (in degrees): the start, midpoint, and end. For example, the lobes in Goode’s interrupted homolosine projection are defined as:

[
  [
    [[-180,   0], [-100,  90], [ -40,   0]],
    [[ -40,   0], [  30,  90], [ 180,   0]]
  ],
  [
    [[-180,   0], [-160, -90], [-100,   0]],
    [[-100,   0], [ -60, -90], [ -20,   0]],
    [[ -20,   0], [  20, -90], [  80,   0]],
    [[  80,   0], [ 140, -90], [ 180,   0]]
  ]
]

Note: interrupted projections typically require clipping to the sphere.

interrupted.lobes([lobes]) Source

If lobes is specified, sets the new array of hemilobes and returns this projection; see d3.geoInterrupt for details on the format of the hemilobes array. If lobes is not specified, returns the current array of hemilobes.

d3.geoInterruptedHomolosine() Source

Goode’s interrupted homolosine projection. Its ocean-centric aspect is also well-known.

d3.geoInterruptedSinusoidal() Source

An interrupted sinusoidal projection with asymmetrical lobe boundaries that emphasize land masses over oceans, after the Swedish Nordisk Världs Atlas as reproduced by C.A. Furuti.

d3.geoInterruptedBoggs() Source

Bogg’s interrupted eumorphic projection.

d3.geoInterruptedSinuMollweide() Source

Alan K. Philbrick’s interrupted sinu-Mollweide projection.

d3.geoInterruptedMollweide() Source

Goode’s interrupted Mollweide projection.

d3.geoInterruptedMollweideHemispheres() Source

The Mollweide projection interrupted into two (equal-area) hemispheres.

Polyhedral Projections

d3.geoPolyhedral(root, face) Source

Defines a new polyhedral projection. The root is a spanning tree of polygon face nodes; each node is assigned a node.transform matrix. The face function returns the appropriate node for a given lambda and phi in radians. Use projection.angle to set the orientation of the map (the default angle, -30°, might change in the next major version).

d3.geoPolyhedralButterfly() Source

The gnomonic butterfly projection.

d3.geoPolyhedralCollignon() Source

The Collignon butterfly projection.

d3.geoPolyhedralWaterman() Source

Steve Waterman’s butterfly projection.

Quincuncial Projections

d3.geoQuincuncial(project) Source

Defines a new quincuncial projection for the specified raw projection function project. The default rotation is [-90°, -90°, 45°] and the default clip angle is 180° - ε.

d3.geoGringortenQuincuncial() Source

The Gringorten square equal-area projection.

d3.geoPeirceQuincuncial() Source

The Peirce quincuncial projection is the quincuncial form of the Guyou projection.

Transformations

d3.geoProject(object, projection) Source

Projects the specified GeoJSON object using the specified projection, returning a shallow copy of the specified GeoJSON object with projected coordinates. Typically, the input coordinates are spherical and the output coordinates are planar, but the projection can also be an arbitrary geometric transformation.

See also geoproject.

d3.geoStitch(object) Source

Returns a shallow copy of the specified GeoJSON object, removing antimeridian and polar cuts, and replacing straight Cartesian line segments with geodesic segments. The input object must have coordinates in longitude and latitude in decimal degrees per RFC 7946. Antimeridian cutting, if needed, can then be re-applied after rotating to the desired projection aspect.

See also geostitch.

d3.geoQuantize(object, digits) Source

Returns a shallow copy of the specified GeoJSON object, rounding x and y coordinates according to number.toFixed. Typically this is done after projecting.

See also geoproject --precision and geo2svg --precision.

Command-Line Reference

geo2svg

geo2svg [options…] [file] Source

Converts the specified GeoJSON file to SVG. With --newline-delimited, each input feature is rendered as a separate path element; otherwise, a single path element is generated.

By default, the SVG’s fill is set to none and the stroke is set to black. The default point radius is 4.5. To override these values on a per-feature basis, the following GeoJSON feature properties will be propagated to attributes:

• fill
• fill-rule (or fillRule)
• fill-opacity (or fillOpacity)
• stroke
• stroke-width (or strokeWidth)
• stroke-linecap (or strokeLinecap)
• stroke-linejoin (or strokeLinejoin)
• stroke-miterlimit (or strokeMiterlimit)
• stroke-dasharray (or strokeDasharray)
• stroke-dashoffset (or strokeDashoffset)
• stroke-opacity (or strokeOpacity)
• point-radius (or pointRadius)

If the feature has an id, the path element will have a corresponding id attribute. If the feature has a title property, the path element will have a title element with the corresponding value. For an example of per-feature attributes, see this California population density map.

Note: per-feature attributes are most useful in conjunction with newline-delimited input, as otherwise the generated SVG only has a single path element. To set these properties dynamically, pass the input through ndjson-map.

geo2svg -h
geo2svg --help

Output usage information.

geo2svg -V
geo2svg --version

Output the version number.

geo2svg -o file
geo2svg --out file

Specify the output file name. Defaults to “-” for stdout.

geo2svg -w value
geo2svg --width value

Specify the output width. Defaults to 960.

geo2svg -h value
geo2svg --height value

Specify the output height. Defaults to 500.

geo2svg -p value
geo2svg --precision value

Reduce the precision for smaller output files. Defaults to six digits after the decimal point. See also d3.geoQuantize.

geo2svg --fill value

Specify the default output fill color. Defaults to none.

geo2svg --stroke value

Specify the default output stroke color. Defaults to black.

geo2svg --r value
geo2svg --radius value

Specify the default output point radius. Defaults to 4.5.

geo2svg -n
geo2svg --newline-delimited

Accept newline-delimited JSON as input, with one feature per line.

geograticule

geograticule [options…] Source

Generates a GeoJSON graticule. See also d3.geoGraticule.

geograticule -h
geograticule --help

Output usage information.

geograticule -V
geograticule --version

Output the version number.

geograticule -o file
geograticule --out file

Specify the output file name. Defaults to “-” for stdout.

geograticule --extent value

Sets the graticule’s extent.

geograticule --extent-minor value

Sets the graticule’s minor extent.

geograticule --extent-major value

Sets the graticule’s major extent.

geograticule --step value

Sets the graticule’s step.

geograticule --step-minor value

Sets the graticule’s minor step.

geograticule --step-major value

Sets the graticule’s major setp.

geograticule --precision value

Sets the graticule’s precision.

geoproject

geoproject [options…] projection [file] Source

Projects the GeoJSON object in the specified input file using the specified projection, outputting a new GeoJSON object with projected coordinates. For example, to project standard WGS 84 input using d3.geoAlbersUsa:

geoproject 'd3.geoAlbersUsa()' us.json \
  > us-albers.json

For geometry that crosses the antimeridian or surrounds a pole, you will want to pass input through geostitch first:

geostitch world.json \
  | geoproject 'd3.geoMercator()' \
  > world-mercator.json

Typically, the input coordinates are spherical and the output coordinates are planar, but the projection can also be an arbitrary geometric transformation. For example, to invert the y-axis of a standard spatial reference system such as California Albers (EPSG:3310) and fit it to a 960×500 viewport:

shp2json planar.shp \
  | geoproject 'd3.geoIdentity().reflectY(true).fitSize([960, 500], d)' \
  > planar.json

See also d3.geoProject and d3.geoIdentity.

geoproject -h
geoproject --help

Output usage information.

geoproject -V
geoproject --version

Output the version number.

geoproject -o file
geoproject --out file

Specify the output file name. Defaults to “-” for stdout.

geoproject -p value
geoproject --precision value

Reduce the precision for smaller output files. See also d3.geoQuantize.

geoproject -n
geoproject --newline-delimited

Accept newline-delimited JSON as input, with one feature per line, and generate newline-delimited JSON as output.

geoproject -r [name=]value
geoproject --require [name=]value

Requires the specified module, making it available for use in any expressions used by this command. The loaded module is available as the symbol name. If name is not specified, it defaults to module. (If module is not a valid identifier, you must specify a name.) For example, to reproject the world on the Airocean projection:

geoproject --require d3=d3-geo-polygon 'd3.geoAirocean()' world.geojson

The required module is resolved relative to the current working directory. If the module is not found during normal resolution, the global npm root is also searched, allowing you to require globally-installed modules from the command line.

Multiple modules can be required by repeating this option.

geoquantize

geoquantize [options…] [file] Source

Reads the GeoJSON object from the specified input file and outputs a new GeoJSON object with coordinates reduced to precision. Same options as geoproject.

geoquantize us.json --precision 3 \
  > us-quantized.json

geostitch

geostitch [options…] [file] Source

Stitches the GeoJSON object in the specified input file, removing antimeridian and polar cuts, and replacing straight Cartesian line segments with geodesic segments. The input object must have coordinates in longitude and latitude in decimal degrees per RFC 7946. Antimeridian cutting, if needed, can then be re-applied after rotating to the desired projection aspect.

See geoproject for an example. See also d3.geoStitch.

geostitch -h
geostitch --help

Output usage information.

geostitch -V
geostitch --version

Output the version number.

geostitch -o file
geostitch --out file

Specify the output file name. Defaults to “-” for stdout.

geostitch -n
geostitch --newline-delimited

Accept newline-delimited JSON as input, with one feature per line, and generate newline-delimited JSON as output.