H3 cell set outline (cellsToMultiPolygon)
The outline of a set of cells: the boundary between the set and everything outside it, as polygons with their holes, in GeoJSON.
The set outlines as 1 piece.
| Part | Ring | Latitude | Longitude |
|---|---|---|---|
| 0 | 0 | 40.449060965 deg | -79.984686025 deg |
| 0 | 0 | 40.448021064 deg | -79.986650906 deg |
| 0 | 0 | 40.446276128 deg | -79.986359370 deg |
| 0 | 0 | 40.445236238 deg | -79.988324096 deg |
| 0 | 0 | 40.443491369 deg | -79.988032515 deg |
| 0 | 0 | 40.442786369 deg | -79.985776361 deg |
| 0 | 0 | 40.441041546 deg | -79.985484889 deg |
| 0 | 0 | 40.440336516 deg | -79.983228886 deg |
| 0 | 0 | 40.441376254 deg | -79.981264245 deg |
| 0 | 0 | 40.440671138 deg | -79.979008283 deg |
| 0 | 0 | 40.441710810 deg | -79.977043529 deg |
| 0 | 0 | 40.443455674 deg | -79.977334694 deg |
| 0 | 0 | 40.444495357 deg | -79.975369785 deg |
| 0 | 0 | 40.446240288 deg | -79.975660906 deg |
| 0 | 0 | 40.446945515 deg | -79.977917089 deg |
| 0 | 0 | 40.448690492 deg | -79.978208319 deg |
| 0 | 0 | 40.449395689 deg | -79.980464654 deg |
| 0 | 0 | 40.448355854 deg | -79.982429649 deg |
| 0 | 0 | 40.449060965 deg | -79.984686025 deg |
- Holes
- Points
- Enclosed area
- South
- West
- North
Provenance
- Computed by
- indexing.h3.cells-to-polygon 1.0.0, core 0.1.0
- Model
- H3 C cellsToMultiPolygon: the boundary segments of every cell, less those walked from both sides, followed end to end
- Accuracy
- The same polygons as H3 C 4.4.1 on 400 cell sets: solid patches, patches with a hole, separate patches, sets around a pentagon, and sets across the antimeridian, at resolutions 3 to 11
- Notes
- None
- Cites
- Uber Technologies and the H3 contributors, H3: A Hexagonal Hierarchical Geospatial Indexing System (API reference v4); Hydronium Labs, h3o: a Rust implementation of H3
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: H3 C cellsToMultiPolygon: the boundary segments of every cell, less those walked from both sides, followed end to end
Accuracy: The same polygons as H3 C 4.4.1 on 400 cell sets: solid patches, patches with a hole, separate patches, sets around a pentagon, and sets across the antimeridian, at resolutions 3 to 11
When to use this: Use this to turn a set of cells back into an area: the outline of a covering, a service area assembled from cells, or a set of cells picked on a map, ready to draw or to hand to something that speaks GeoJSON. It is the inverse of filling a polygon with cells.
Limitations: Every cell must be at one resolution, so compact a mixed set back to one resolution first. The outline follows cell edges, so it is the boundary of the cells rather than of whatever they were meant to approximate, and at a coarse resolution the two differ by up to a cell. A set in separate pieces comes back as separate polygons, and a piece wrapped around a gap comes back with a hole.
Worked example: A cell and its six neighbors outline as one hexagon of 18 sides. Source: H3 cellsToMultiPolygon. It is golden test vector v002, and every build checks the tool still gives its answer within its tolerance.
You enter
- Cells
- 892a8471483ffff 892a8471487ffff 892a847148fffff 892a8471497ffff 892a84714b3ffff 892a84714bbffff 892a847334bffff
You get
- Pieces
- 1
- Holes
- 0
- Points
- 19
- Enclosed area
- 0.737325 km²
- South
- 40.440336516°
- West
- -79.988324096°
- North
- 40.449395689°
- East
- -79.975369785°
- GeoJSON
- {"type":"MultiPolygon","coordinates":[[[[-79.984686025,40.449060965],[-79.986650906,40.448021064],[-79.986359370,40.446276128],[-79.988324096,40.445236238],[-79.988032515,40.443491369],[-79.985776361,40.442786369],[-79.985484889,40.441041546],[-79.983228886,40.440336516],[-79.981264245,40.441376254],[-79.979008283,40.440671138],[-79.977043529,40.441710810],[-79.977334694,40.443455674],[-79.975369785,40.444495357],[-79.975660906,40.446240288],[-79.977917089,40.446945515],[-79.978208319,40.448690492],[-79.980464654,40.449395689],[-79.982429649,40.448355854],[-79.984686025,40.449060965]]]]}
Review: Not yet independently reviewed by a GIS professional.
Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Checked against: 24 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- H3: A Hexagonal Hierarchical Geospatial Indexing System (API reference v4), Uber Technologies and the H3 contributors, H3 4.x documentation. Indexing, inspection, traversal, hierarchy, directed edges, vertexes, and resolution tables. Read free.
- h3o: a Rust implementation of H3, Hydronium Labs, 0.11.0 (tested against H3 C). CellIndex, LatLng, Resolution. Read free.
Terms
- H3: H3 hexagonal hierarchical index
- A global grid of hexagons (and 12 pentagons) at 16 resolutions, each cell about one-seventh the area of its parent, named by a 15-character index. Source: H3 hexagonal index
H3 — H3 hexagonal hierarchical index
A global grid of hexagons (and 12 pentagons) at 16 resolutions, each cell about one-seventh the area of its parent, named by a 15-character index.
Source: H3 hexagonal index