rHEALPix grid

The rHEALPix discrete global grid system — an equal-area aperture-9 quadtree on the WGS84 ellipsoid, built from the HEALPix projection with the polar caps reassembled into squares. Six faces (N O P Q R S) subdivide into 9 children each (N0 … N8), so every cell at a given resolution covers exactly the same ground area, from ~85 million km² at resolution 0 down to under a square metre at resolution 15.

The interactive explorer below is rendered with deck.gl and behaves like the h3geo.org map: the rHEALPix resolution follows the zoom and cells are generated in the browser for whatever is in view. Two neighbouring resolutions are shown at once — the current level with a darker, heavier border and the next finer level with a lighter, thinner one — so the aperture-9 nesting stays visible. It is powered by the shared m3s_core Rust/WASM build so the cell ids and edges match M3S exactly. GIS-native (lon, lat) order is used throughout.

Why rHEALPix?

rHEALPix is the standards-track equal-area DGGS (it has an OGC specification and powers several national scientific data cubes): exact equal-area cells, exact 9-way nesting, readable hierarchical ids (each child appends one digit), and clean polar coverage — the poles are ordinary square cells, not singularities. Cells are squares in the projection; on the ground they stay square-ish at mid-latitudes and become more skewed in the polar caps. Choose EA-Quad grid when you want km-labelled square cells in a single metric projection, A5 grid for equal-area pentagons with the lowest shape distortion, or H3 grid for hexagonal analytics where approximate equal area is acceptable.

Usage

Encode a point and tile a small bounding box around Paris — same result in Python and JavaScript (both call the shared core):

Python

import m3s

cell = m3s.RHEALPix.from_geometry((2.35, 48.86))            # (lon, lat)
cells = m3s.RHEALPix.from_geometry((2.2, 48.8, 2.4, 48.9))  # bbox
print(cell.id, len(cells))

JavaScript

import * as m3s from "m3s";
await m3s.ready();

const cell = m3s.RHEALPix.fromPoint(2.35, 48.86);            // (lon, lat)
const cells = m3s.RHEALPix.fromBbox([2.2, 48.8, 2.4, 48.9]); // bbox
console.log(cell.id, cells.length);

from _deckmap import DeckExplorer, read_grid_js


DeckExplorer(
    center=(2.35, 48.86),
    zoom=9,
    grid_js=read_grid_js("rhealpix"),
    hover="#44AA99",
    wasm=True,
)