Format

SDO_UTIL.H3_KEY(
 longitude  IN NUMBER,
 latitude   IN NUMBER,
 resolution IN NUMBER DEFAULT 15) RETURN RAW;

SDO_UTIL.H3_KEY(
 geometry   IN mdsys.sdo_geometry,
 resolution IN NUMBER DEFAULT 15) RETURN RAW;

Description

Returns the H3 cell for the given geodetic point and resolution.

Parameters

longitude

The longitude of the input point.

latitude

The latitude of the input point.

geometry

A geometry consisting of a single point in a geodetic coordinate system. SRID must be non-null. If it is not SRID 4326, then the point will be transformed to SRID 4326.

resolution

The resolution of the H3 cell to return, from zero (coarsest) to 15 (finest).

Usage Notes

The SDO_UTIL.H3_KEY function converts point locations to the hexagonal hierarchical spatial indexing system designed by Uber. This indexing system divides the world into 122 resolution 0 cells of 4.4 million km² each at the top level (level 0). Cells are mapped onto an icoshedron (regular 20-sided polyhedron). Each increase in resolution subdivides into smaller cells until level 15 which has 569,707,381,193,162 cells of about 1 m² each. The cells are hexagons except for 12 pentagons at each level (a sphere cannot be tiled with just hexagons). Note that a hexagon cannot be subdivided exactly with hexagons. As a result, cells near the border of their parent cell are not perfectly contained in their parent cell.

H3 is always computed in SRID 4326 coordinate system.

Examples

The following example shows an H3 cell in Paris:

SELECT SDO_UTIL.H3_KEY(48.85755957774311, 2.344920508484808, 7) FROM DUAL;
0877AA5145FFFFFF

The following example shows the smallest H3 cell (level 15) containing the North Pole:

SELECT SDO_UTIL.H3_KEY(SDO_GEOMETRY(2001, 4326, SDO_POINT_TYPE(0, 90, NULL), NULL, NULL), 15);
08F0326233AB0399