Maps — and other representations of the world.
Dotted OceansWorld Cities GabrielAntipodal ArchipelagoBi-Hexagonal ProjectionParis, TexasUSSR, 1938IGRF-90🌖 Crater-shadingModified Stereographic Alaska GLSLVolcano on A-FrameBorn in AntarcticaNatural Earth issuesHello, spl.jsNéguentropieLoir-et-Cher isodémographiqueTheoretical land coverFive OceansPantelleria Joy PlotRouting dollarsDeriving PantelleriaGuessing CzechoslovakiaGHSL — Growing and decliningHistorical shapefilesThe E.N.D GameAnn Arbor pycnophylacticSpherical signed distanceWalk-on-Spheres… on a SpherePotential dollar flowsThirty days and as many maps
Hex NDVI
image = Object.assign(
await /*d3.image(
"https://neo.sci.gsfc.nasa.gov/servlet/RenderData?si=1778973&format=PNG&width=720&height=360",
{ crossOrigin: "anonymous" }
) */ FileAttachment(
"ndvi.png"
).image(),
{ style: "max-width:300px" }
)
height = 800
data = {
const width = image.naturalWidth,
height = image.naturalHeight;
const context = DOM.context2d(width, height, 1);
context.drawImage(image, 0, 0);
return context.getImageData(0, 0, width, height).data;
}
function value([lon, lat]) {
const x = Math.round(((lon + 180) / 360) * image.naturalWidth),
y = Math.round(((90 - lat) / 180) * image.naturalHeight),
i = x + y * image.naturalWidth;
const v = 255 - data[4 * i + 1]; // read the green channel
return v < 1 ? NaN : v / 255;
}
import { grid } from "@fil/gray-fuller-grid"
points = grid(N)
cells = d3.geoVoronoi(points).polygons()
color = d3.scaleSequential((t) => d3.interpolateGreens(1 - t))
projection = d3
.geoSatellite()
.rotate([360 * Math.random(), -45])
.fitExtent(
[
[10, 10],
[width - 10, height - 10]
],
{ type: "Sphere" }
)
merge = (f) => {
const topo = topojson.topology({ f });
return topojson.merge(topo, topo.objects.f.geometries);
}
// group by color and merge the cells for faster rendering
groups = d3.rollup(
d3.range(points.length),
(index) =>
merge({
type: "FeatureCollection",
features: index.map((i) => cells.features[i])
}),
(i) => Math.round(value(points[i]) * 10) / 10
)
function render(context, path) {
function draw() {
for (const [value, f] of groups) {
if (isNaN(value)) continue;
context.beginPath();
path(f);
context.fillStyle = color(value);
context.fill();
}
}
// dark blue sphere
context.fillStyle = "#000";
context.fillRect(0, 0, width, height);
context.beginPath();
path({ type: "Sphere" });
context.fillStyle = "#003";
context.fill();
const clipAngle = projection.clipAngle();
context.globalAlpha = 0.3;
projection.clipAngle(180);
draw();
// front globe
context.globalAlpha = 1;
projection.clipAngle(clipAngle);
draw();
}
d3 = require("d3@7", "d3-geo-projection@4", "d3-geo-voronoi@2", "d3-inertia@0.2")
topojson = require("topojson-server@3", "topojson-client@3")
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