Published
Edited
May 6, 2021
Importers
11 stars
Contour Labels (canvas)Coordinated mapsgeoformatSmall circle testKruskal MazeAll the geoshapesReprojecting Vector TilesCloud ContoursHello h3-jsClipping AlbersTranslucent EarthThe truth about the Mercator projectionUsing d3-inertia with observableMercator projection of a Mercator globeD3 Vector Tiles (WIP)Finding intersections between the graticule and the clip sphere of the stereographic projection, method 2Plate tectonicsAnother hex mapEquateur & tropiquesTissot's indicatrixDistance to shoreMultiPolygon clippingSouth Africa’s medial axisSpherical intersectionVolcano Semis (points circulaires)Pencil Airocean45° mapNetCDFBlue noise sphereRubber DymaxionSpherical quasi-random (R2) distributionAutomated label placement (countries)Automated label placement (France)Automated label placement (cities)d3.geoIntersectArcDelaunay.findTriangled3-geo-voronoi and gridded dataElevation vtk.jsMapfillKrigingSpherical HeatmapReproject elevation tiles — detailReproject elevation tiles — worldFisheye Conformal MapSpherical KDE InterpolationSpherical kernel interpolation with nearest neighborsShepard’s methodModified Shepard’s methodSpherical contoursGeo Voronoi interpolationBlurry contoursHow much warmer? (BBC)H3 hexagons & geoContoursHillshading & supersamplingH3 odditiesManhattan VoronoiManhattan Voronoi IIGeoJSON feature editorColorized Manhattan Spanning Treelegra mapslegra country mapsThe complex logarithm projectionCountries small multipleThe 2D approximate Newton-Raphson methodOceanAttitudeCount visible objectsThe Gray-Fuller spatial gridGray-Fuller grid metricsGray-Fuller grid odditiesBounding CirclesCountries Enclosing CirclesFullscreen Seamless Zoomable Map TilesMap Pan & ZoomSpherical EllipsesSynchronized projectionsThe closest countryTriangular tiling of icosahedronHello, polygon-clippingCorées / KoreasHello, procedural-glHello, placekeyZoom World ChoroplethClipping spherical polygonsSpherical phyllotaxisFour-color world map with ClingoHello, jsgeoda!The Sun’s analemmaWorld of squaresWorld of squares (spherical)A map of AfricaTagged bordersClipped geoVoronoiBlue noise sphere IISpherical Perlin NoiseSpherical Delaunay triangulationDynamic simplificationRewindPlot: Voronoi labelsAoC 12: shortest path under constraintsHello, pixi.jsFlight PathsRay out of a convex hullDistance to a segment
Spherical smallest-circle problem
Also listed in…
Clustering
projection = show_stereo ? stereo : d3.geoOrthographic().rotate([0, -15])
centroid = d3.geoCentroid({ type: "MultiPoint", coordinates: points })
stereo = d3.geoStereographic().rotate(centroid.map(d => -d))
stereoCircles = points =>
points.map(d => {
const g = d3
.geoCircle()
.center(d)
.radius((d[2] || 0) + .2)().coordinates[0],
f = [g[0], g[20], g[40]].map(stereo), // sample 3 of the 60 points given by geoCircle
c = circumcenter(f);
return {
x: c[0],
y: c[1],
r: Math.hypot(c[0] - f[0][0], c[1] - f[0][1])
};
})
// inspect
stereoCircles(points)
enclose = points => {
const centroid = d3.geoCentroid({ type: "MultiPoint", coordinates: points });
stereo.rotate(centroid.map(d => -d));
const { x, y, r } = d3.packEnclose(stereoCircles(points));
// the center of the spherical circle can be retrieved with a geoVoronoi of 3 of its points
const f = [[x + r, y], [x - r, y], [x, y + r]].map(stereo.invert),
c = d3.geoVoronoi(f).triangles().features[0].properties.circumcenter;
// for very large lists, c can be on the opposite side, check for that…
if (d3.geoDistance(c, centroid) > Math.PI / 2) {
c[0] += 180;
c[1] *= -1;
}
return { c, r: (d3.geoDistance(c, f[0]) * 180) / Math.PI };
}
// inspect
circle = enclose(points)
height = 500
points = Array.from({ length: N }, () => [
360 * Math.random(),
90 - S * Math.random(),
R * Math.random()
])
function distance2(A, B) {
return (A[0] - B[0])*(A[0] - B[0])+(A[1] - B[1])*(A[1] - B[1]);
}
circumcenter = ([A, B, C]) => {
const a2 = distance2(B, C),
b2 = distance2(C, A),
c2 = distance2(A, B),
// barycentric weights
a = a2 * (b2 + c2 - a2),
b = b2 * (a2 + c2 - b2),
c = c2 * (b2 + a2 - c2),
d = a + b + c;
return [
(A[0] * a + B[0] * b + C[0] * c) / d,
(A[1] * a + B[1] * b + C[1] * c) / d
];
}
d3 = require("d3@5", "d3-geo-voronoi")
import { checkbox, slider } from "@jashkenas/inputs"
import { drag } from "@fil/versor-dragging-with-attitude"
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