Ninjas Practicing Multidimensionality

    @high-u/quadkeytools

    0.0.2 • Public • Published

    quadkeytools

    Forked

    Forked from https://bitbucket.org/steele/quadkeytools/src/master

    Describe

    A library to calculate unique keys that represent tiles in a quadtree grid for geo-coordinates. We will call these unique keys quadkeys. This was based off code put out by the Bing maps team http://msdn.microsoft.com/en-us/library/bb259689.aspx

    About

    Projection

    In order to map a 2D plane on to the globe you have to use projection. This library uses Mercator projection. Which looks like this:

    Mercator Projection Image

    Detail Level

    Once the globe is projected on to a 2D plane we can cut it up into quadrants then quadruple it's area and cut each quadrant into subquadrants. Each time the plane is increased in size we increase the detail level of each quadrant.

    QuadkeyTools

    Every time we increase the detail level we mark each subquadrant with a 0, 1, 2, or 3. Looks something like this:

    Quadtree

    Installation

    npm install quadkeytools

    Usage

    locationToQuadkey( location, detail )

    Get the quadkey for lat,lng at a specific detail

    import { locationToQuadkey } from "quadkeytools";
    const location = { lat: 40.01234, lng: -160.02324 };
    const detail = 16;
    const key = locationToQuadkey(location, detail);

    bbox( quadkey )

    Get the bounding box for a quadkey. Detail level is inferred by the length of the key.

    import { bbox } from "quadkeytools";
    const key = '11002122';
    const bbox = bbox(key);

    origin( quadkey )

    Get the center origin lat,lng of a quadkey

    import { origin } from "quadkeytools";
    const key = '12332110';
    const origin = origin(key);

    inside( location, quadkey )

    Check if a lat,lng is within the bounds of a quadkey. Returns true if the location is inside the quadkey and false otherwise. Detail level is inferred by the size of the key.

    import { inside } from "quadkeytools";
    const key = '00231211';
    const location = { lat: 40.01234, lng: -160.02324 };
    const isInside = inside(location, key);

    children( quadkey )

    Get all the children of a quadkey. This will return an array of keys representing the subquadrants at the next detail level.

    import { children } from "quadkeytools";
    const key = '0123332111';
    const children = children(key);

    sibling( quadkey, direction )

    Get a sibling of a quadkey. This will return the key of a sibling in a particular direction. Directions can be 'left' 'right' 'up' or 'down'.

    import { sibling } from "quadkeytools";
    const key = '001';
    const sibling = sibling(key, 'left');

    parent( quadkey )

    Get the parent of a quadkey. This will return the quadkey that represents the parent quadrant in the previous detail level.

    import { parent } from "quadkeytools";
    const key = '0012223';
    const parent = parent(key);

    locationToPixel( location, detail )

    Convert lat,lng to pixel coordinates. Note - Pixel coordinates are Integers so precision will be lost.

    import { locationToPixel } from "quadkeytools";
    const location = { lat: 40.01234, lng: -160.02324 };
    const detailLevel = 10;
    const pixel = locationToPixel(location, detailLevel);

    pixelToLocation( pixel, detail )

    Convert pixel coordinates to lat,lng.

    import { pixelToLocation } from "quadkeytools";
    const pixel = { x: 14547, y: 99231 };
    const location = pixelToLocation(pixel, 10);

    pixelToTile( pixel )

    Convert pixel coordinates to tile coordinates

    import { pixelToTile } from "quadkeytools";
    const pixel = { x: 14547, y: 99231 };
    const tile = pixelToTile(pixel);

    tileToPixel( tile )

    Convert tile coordinates to pixel coordinates

    import { tileToPixel } from "quadkeytools";
    const tile = { x: 12, y: 200 };
    const pixel = tileToPixel(tile);

    tileToQuadkey( tile, detail )

    Convert tile coordinates to a quadkey at a specific detail level

    import { tileToQuadkey } from "quadkeytools";
    const tile = { x: 220, y: 45 };
    const detail = 10;
    const key = tileToQuadkey(tile, detail);

    quadkeyToTile( quadkey )

    Get the tile coordinates of a quadkey. This will be the coordinates of the corner of the quadkey.

    import { quadkeyToTile } from "quadkeytools";
    const key = '000123220';
    const tile = quadkeyToTile(key);

    tileToLocation( tile, detail )

    Get the lat,lng coordinates of a tile's corner for a specific detail level.

    import { tileToLocation } from "quadkeytools";
    const tile = { x: 220, y: 12 };
    const detail = 4;
    const location = tileToLocation( tile, detail );

    Install

    npm i @high-u/quadkeytools

    DownloadsWeekly Downloads

    4

    Version

    0.0.2

    License

    BSD-3-Clause

    Unpacked Size

    88.6 kB

    Total Files

    5

    Last publish

    Collaborators

    • high-u