Spatial indexing

Moving between indexing systems: one place in each, at resolutions chosen to match a cell size.

• One place in every index, at a matched cell size

  A point written as an H3 cell, an S2 cell, a geohash, a Plus Code, a map tile, a Maidenhead locator, and an MGRS reference, each at the resolution whose cell is closest to the size you name, with the size it actually has there.

Geohash encoding, decoding, and neighbors.

• Geohashes covering an area

  Every geohash at a precision that touches a bounding box or polygon, or only those whose centers fall inside, for indexing or querying an area.

• Geohash decoder

  The center, bounding box, and error margins of a geohash.

• Geohash encoder

  The geohash for a latitude and longitude at precision 1 to 12, with the cell's size and bounds.

• Geohash neighbors

  The 8 geohash cells around a geohash, wrapping across the antimeridian; past a pole there is no neighbor.

Uber's H3 hexagonal grid.

• H3 cell inspector

  Everything about an H3 cell: center (cellToLatLng), boundary (cellToBoundary), resolution, base cell, pentagon and Class III checks, area, and decimal form.

• H3 local IJ for a cell (cellToLocalIj)

  The local IJ coordinates of a cell as seen from an origin cell: two whole numbers on the grid H3 unfolds around that origin.

• H3 cell set outline (cellsToMultiPolygon)

  The outline of a set of H3 cells: the boundary between the set and everything outside it, as polygons with their holes, in GeoJSON.

• H3 children cells

  The finer H3 cells inside a cell (cellToChildren), their count, and the center child.

• H3 compact

  Replaces every complete group of 7 sibling cells with their parent, repeatedly, for the smallest set covering the same area (compactCells).

• H3 edges and vertexes

  The directed edges (with lengths and neighbors) and vertexes of an H3 cell (originToDirectedEdges, cellToVertexes).

• H3 grid disk (k-ring)

  All H3 cells within k steps of a cell (gridDisk); fewer than 3k(k+1)+1 when a pentagon is nearby.

• H3 grid path and distance

  The grid distance between two H3 cells (gridDistance) and the line of cells joining them (gridPathCells).

• H3 grid ring

  The H3 cells exactly k steps from a cell (gridRing), the hollow ring.

• H3 cell for a point

  The H3 cell containing a latitude and longitude at resolution 0 to 15 (latLngToCell), with the cell's center and area.

• H3 cell at local IJ (localIjToCell)

  The H3 cell at local IJ coordinates around an origin cell, undoing cellToLocalIj.

• H3 parent cell

  The coarser H3 cell that contains a cell (cellToParent), and the cell's position among that parent's children.

• H3 polygon fill (polygonToCells)

  The H3 cells that fill a polygon (with holes, across the antimeridian) at a resolution, by an explicit containment mode: cell centers inside, whole cells inside, or any overlap.

• H3 resolution chooser

  The H3 resolution whose average cell is closest to a target area or edge length, with the full resolution table (122 base cells, 12 pentagons at each resolution).

• H3 uncompact

  Expands a mixed-resolution set of H3 cells to one resolution (uncompactCells).

Open Location Codes (Plus Codes).

• Plus Code decoder

  The center and area of a Plus Code; a short code needs a nearby reference point to recover the full code.

• Plus Code encoder

  The Plus Code (Open Location Code) for a latitude and longitude at code length 2 to 15, with the area it covers.

• Shorten a Plus Code

  The shortest form of a full Plus Code that still recovers uniquely near a reference point (such as the nearest town).

S2 cells: a point to a cell id or token at any level, what a cell covers, and the cells across its edges.

• S2 cell details

  Everything about an S2 cell: its center, its four corners, the face and level, its exact area against the average for that level, and its parent and children.

• S2 cells covering a region

  The S2 cells that cover a latitude and longitude rectangle, or a circle around a point, within a level range and a cell budget.

• S2 cell for a point

  The S2 cell containing a latitude and longitude at a level from 0 to 30, with its token, its 64-bit id, the face it sits on, and its area.

• S2 edge neighbours

  The four cells across an S2 cell's edges, at the same level, wrapping onto the next cube face where the cell lies on a face edge.

Web map tiles and ground resolution.

• Map tile bounds

  The latitude and longitude bounds of a z/x/y tile or quadkey, with its XYZ, TMS, and quadkey forms; detect mode shows both y conventions.

• Map tiles covering a box

  Every z/x/y tile at a zoom that touches a latitude and longitude box, across the antimeridian when west is greater than east, for pre-caching or download planning.

• Map tile parent and children

  The parent tile one zoom out and the four children one zoom in of a z/x/y tile or quadkey, in XYZ or TMS numbering.

• Map tile for a point (XYZ, TMS, quadkey)

  The web map tile containing a point at a zoom: XYZ, TMS, and quadkey, with the ground resolution.

• Map ground resolution and scale

  Meters per pixel and map scale for a Web Mercator zoom level at a latitude, for 256 or 512 pixel tiles.