Live demo

Explore grids and coverage, interactively.

Compare seven grid systems, inspect cells, and draw coverage queries. Use the same CARTO vector basemap in Globe or Flat view.

On this page

Live demo: 7 grid systems, one map

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Controls

System

T3 base resolution

Group as

Hierarchy

Projection

Trifold triangles vs A5 pentagons, H3 hexagons, S2 quads, rHEALPix, HTM (a related octahedral grid) and a plain lon/lat grid. Each layer uses the same land mask and styling. Toggle globe ↔ flat to compare the globe and Mercator projections; click any cell for its address and properties.

Coverage demo: bbox_cover and polyfill

Controls

Draw

Compare

Level

L6 ~110 km

Selection

Output

Index

Drag to draw a bbox, or switch to polygon and click vertices.

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Coverage is conservative in intersects mode. The index list is T3; S2 is shown on the map and in the stats. S2 cells are real Google S2 quads (quadratic projection, Hilbert order); the cover is fixed-level to mirror T3's, not S2's variable-level region coverer.

Draw a query shape and Trifold returns stable indexes for the triangular cells that overlap it. The full output is fixed-level cells; compacted output folds complete sibling sets into variable-level parents; ranges are addr64 intervals for subtree scans. Switch on T3 + S2 to cover the same shape with Google S2 cells (computed live in the browser, area-matched level) and compare how much each grid's quadtree compaction folds away.

Land mask: Natural Earth. Comparison layers via pya5, h3-py, s2sphere and rhealpixdggs. Grid comparison and trade-offs · SDK API