GeoTileHash

This function encodes the slippy tilenames z/x/y tree into a single string hash that is easy to search.

This is convenient for doing bounding rectangle searches on a DB system like dynamoDB.

Examples:

// 
gridify(-180, minLat - 0.0000001)
// '0000000000000000'

const tile4Input = [ -125.20019531249999, 46.56641407568593, -119.783935546875, 49.880477638742555 ]
getRelevantHashes(tile4Input)
// ['021221', '021230', '021203', '021212']

Methods:

gridify(lng, lat, zoomLevel)

Return a hash up to maxZoom characters long corresponding to the lat/lng coordinates.

degridify(hashVal)

inputs the hashVal you got from gridify and returns

Returns the bounding box of this hashval slippy tiles it corresponds to:

{
    bounds: [minLng, minLat, maxLng, maxLat],
    tiles: [z,x,y]
}

smallestHash([minLng, minLat, maxLng, maxLat])

This returns the smallest single hash in common with all 4 corners of this bounding rectangle.

Be careful when using this function. Adjacent tiles that are separated by zoom boundaries will not have a hash in common

getRelevantHashes([minLng, minLat, maxLng, maxLat])

Input a bounding rectangle and output an array of between 1 and 4 hashes corresponding to the number of adjacent tiles that contain the bounding rectangle.

long2tile(lng, z)

From: https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames

lat2tile(lat, z)

From: https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames

tile2long(xTile, z)

From: https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames

tile2lat(yTile, z)

From: https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames