Published
Edited
Jul 27, 2019
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6 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 — detailFisheye 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 odditiesSpherical smallest-circle problemBounding 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
Reproject elevation tiles — world
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Projections
projection = d3
.geoCahillKeyes()
.fitExtent([[1, 1], [width - 1, height - 1]], outline)
earth = d3.scaleSequential(d3.interpolateOranges).domain([0, 5000])
sea = d3.scaleSequential(d3.interpolateBlues).domain([0, -8000])
url = (x, y, z) =>
`https://tile.nextzen.org/tilezen/terrain/v1/256/terrarium/${z}/${x}/${y}.png?api_key=${api_key}`
w = tileSize
h = tileSize
mutable dem = DOM.canvas(w, h)
// the DEM tiles we load should encompass the whole area, and fall on exact screen coordinates (tx, ty are integers, and k equal to 256.
mercator = {
const mercator = d3.geoMercator().fitExtent([[0, 0], [w, h]], outline),
tiles = d3
.tile()
.size([w, h])
.scale(mercator.scale() * 2 * Math.PI)
.translate(mercator([0, 0]))(),
k = tileSize / tiles.scale;
return mercator
.scale(mercator.scale() * k)
.translate(mercator.translate().map(d => Math.round(d * k)));
}
tiles = d3
.tile()
.size([w, h])
.scale(mercator.scale() * 2 * Math.PI)
.translate(mercator([0, 0]))()
loader = {
const context = mutable dem.getContext("2d");
context.fillStyle = "#800000";
context.fillRect(0, 0, w, h);
tiles.forEach(([x, y, z], i, { translate: [tx, ty], scale: k }) => {
d3.image(url(...d3.tileWrap([x, y, z])), { crossOrigin: "Anonymous" }).then(
image => {
context.drawImage(image, (x + tx) * k, (y + ty) * k, k, k);
mutable dem = mutable dem;
}
);
});
return `loading ${tiles.length} tiles...`;
}
api_key = "7b1mrgvcThKgwl1ZslAhKQ" // claim your own API key at https://developers.nextzen.org/
rescale = d3.scaleSqrt()
data = {
const d = dem.getContext("2d").getImageData(0, 0, w, h).data,
val = (_, i) => {
const j = (h - 1 - ((i / w) | 0)) * w + (i % w), // flip
v = 256 * d[4 * j] + d[4 * j + 1] + d[4 * j + 1] / 256 - 32768;
return rescale(v);
};
return Float32Array.from({ length: w * h }, val);
}
contours = {
const contours = d3
.contours()
.size([w, h])
.thresholds(50)(data);
for (const c of contours) {
for (const polygon of c.coordinates)
for (const ring of polygon) {
for (var i = 0; i < ring.length; i++)
ring[i] = mercator.invert([ring[i][0] - 0.5, w - (ring[i][1] - 0.5)]); // flop
}
}
return contours;
}
extent = d3.extent(contours, d => rescale.invert(d.value))
// this is the area we want to cover
outline = ({ type: "Sphere" })
height = width / 2
tileSize = 256
d3 = require("d3@5", "d3-geo-projection@2", "d3-geo-polygon@1", "d3-tile@1")
land = d3.json(
"https://unpkg.com/visionscarto-world-atlas@0.0.6/world/110m_land.geojson"
)
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