Realtime Rain Radar (Japan)Flood depth map on 3D terrainTest: Mapbox GL JS v2Drawing isobar on mapAsteroid Itokawa 3D [9MB]Pseudo-contouringDecoding PNG elevation tileJapan FloodBilinear interpolation of tileGradient of MountainContoured mountainious terrain 3DDem to contour by d3H3 index visualizerFetch elevation tileMapbox GL + GeoJSON PolygonH3 GeoJsonMountain Terrain 3D
Overlay DIY contour on map
// Calculate lat/lon of pixel (pX, pY) on tile tileZ/tileX/tileY
function pixelOnTileToLatLon(pX, pY, tileZ, tileX, tileY) {
const L = 85.05112878;
const x = 256 * tileX + pX;
const y = 256 * tileY + pY;
const lon = 180 * (x / (2**(tileZ+7)) - 1);
const lat = (180/Math.PI) * math.asin(math.tanh(
-Math.PI/(2**(tileZ+7)) * y + math.atanh(math.sin(L * Math.PI/180))
));
return {lat: lat, lon: lon}
}
data = transformContour(contours)
function transformContour(contours) {
return contours.map(({type, value, coordinates}) => (
{type, value, coordinates: coordinates.map(rings => (
rings.map(points => (
points.map(([x, y]) => {
const coord = pixelOnTileToLatLon(x, y, tile.z, tile.x, tile.y);
return [coord.lon, coord.lat];
})
))
))}
));
}
function overlayContour() {
data.forEach((d, i) => {
map.addSource(`contour${i}`, {
type: "geojson",
data: d,
});
map.addLayer({
"id": `contourLayer${i}`,
"type": "line",
"source": `contour${i}`,
"layout": {},
"paint": {
"line-width": 2,
"line-color": color(d.value),
"line-opacity": 0.8
}
});
})
}
map.on("load", overlayContour);
// Manually update map on slider event
d3.select("#interval").on("change", () => {
// Remove old contours
map.getStyle().layers.forEach(l => {
if (l.id.startsWith("contourLayer")) {
map.removeLayer(l.id);
}
});
Object.keys(map.getStyle().sources).forEach(k => {
if (k.startsWith("contour")) {
map.removeSource(k)
}
})
overlayContour();
});
tile = ({z: 13, x: 7262, y: 3232})
// Fetch dem data as 256 x 256 array
dem = fetchTile(tile)
One platform to build and deploy the best data apps
Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.
Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.
Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.