sphericalmercator

Provides projection math for converting between mercator meters, screen pixels (of 256x256 or configurable-size tiles), and latitude/longitude. Compatible with nodejs packages and in-browser.

See also

* tilebelt provides ZXY tile math utilities in javascript
* mercantile provides similar utilities for projection and tile math in Python

Installation

npm install @mapbox/sphericalmercator

API

Some datatypes are assumed to be arrays: ll is [lon, lat], xy and px are [x, y].

``javascript
import { SphericalMercator } from '@mapbox/sphericalmercator';

// By default, precomputes up to z30
const merc = new SphericalMercator({
size: 256,
antimeridian: true
});
`

or, for CommonJS:

`javascript
const { SphericalMercator } = require('@mapbox/sphericalmercator');
`

$3

Convert lon, lat to screen pixel x, y from 0, 0 origin, at a certain zoom level. The inverse of ll. If antimeridian: true is passed on initialization of the SphericalMercator object, this method will support converting longitude values up to 360°.

$3

Convert screen pixel value to lon, lat, at a certain zoom level. The inverse of px.

$3

Convert tile xyz value to bbox of the form [w, s, e, n]

* x {Number} x (longitude) number.
* y {Number} y (latitude) number.
* zoom {Number} zoom.
* tmsStyle {Boolean} whether to compute using tms-style. (optional, default false)
* srs {String} projection for resulting bbox (WGS84|900913). (optional, default WGS84)

Returns bbox array of values in form [w, s, e, n].

$3

Convert bbox to xyz bounds

* bbox {Number} bbox in the form [w, s, e, n].
* zoom {Number} zoom.
* tmsStyle {Boolean} whether to compute using tms-style. (optional, default false)
* srs {String} projection of input bbox (WGS84|900913). (optional, default WGS84)

Returns {Object} XYZ bounds containing minX, maxX, minY, maxY properties.

$3

Convert bbox from 900913 to WGS84 or vice versa

* bbox {Number} bbox in the form [w, s, e, n].
* to {String} projection of resulting bbox (WGS84|900913). (optional, default WGS84)

Returns bbox array of values in form [w, s, e, n].

$3

Convert lon, lat values to mercator x, y

$3

Convert mercator x, y values to lon, lat

Developing

`sh
npm ci # install
npm test # run tests
npm run format # format files with prettier
``