Projection~Projection

import Projection from 'ol/proj/Projection.js';

In most cases, you should not need to create instances of this class. Instead, where projection information is required, you can use a string projection code or identifier (e.g. EPSG:4326) instead of a projection instance.

The library includes support for transforming coordinates between the following projections:

WGS 84 / Geographic - Using codes EPSG:4326, CRS:84, urn:ogc:def:crs:EPSG:6.6:4326, urn:ogc:def:crs:OGC:1.3:CRS84, urn:ogc:def:crs:OGC:2:84, http://www.opengis.net/gml/srs/epsg.xml#4326, or urn:x-ogc:def:crs:EPSG:4326 WGS 84 / Spherical Mercator - Using codes EPSG:3857, EPSG:102100, EPSG:102113, EPSG:900913, urn:ogc:def:crs:EPSG:6.18:3:3857, or http://www.opengis.net/gml/srs/epsg.xml#3857 WGS 84 / UTM zones - Using codes EPSG:32601 through EPSG:32660 for northern zones and EPSG:32701 through EPSG:32760 for southern zones. Note that the built-in UTM transforms are lower accuracy (with errors on the order of 0.1 m) than those that you might get in a library like proj4js.

For additional projection support, or to use higher accuracy transforms than the built-in ones, you can use the proj4js library. With proj4js, after adding any new projection definitions, call the register function.

You can use the get function to retrieve a projection instance for one of the registered projections.

new Projection(options) proj/Projection.js, line 62

Name	Type	Description
`code`	string	The SRS identifier code, e.g. `EPSG:4326`.
`units`	Units \| undefined	Units. Required unless a proj4 projection is defined for `code`.
`extent`	Extent \| undefined	The validity extent for the SRS.
`axisOrientation`	string (defaults to 'enu')	The axis orientation as specified in Proj4.
`global`	boolean (defaults to false)	Whether the projection is valid for the whole globe.
`metersPerUnit`	number \| undefined	The meters per unit for the SRS. If not provided, the `units` are used to get the meters per unit from the `METERS_PER_UNIT` lookup table.
`worldExtent`	Extent \| undefined	The world extent for the SRS.
`getPointResolution`	GetPointResolution \| undefined	Function to determine resolution at a point. The function is called with a `number` view resolution and a `Coordinate` as arguments, and returns the `number` resolution in projection units at the passed coordinate. If this is `undefined`, the default `getPointResolution` function will be used.

Methods

getAxisOrientation(){string} proj/Projection.js, line 204

Get the axis orientation of this projection. Example values are: enu - the default easting, northing, elevation. neu - northing, easting, up - useful for "lat/long" geographic coordinates, or south orientated transverse mercator. wnu - westing, northing, up - some planetary coordinate systems have "west positive" coordinate systems

Returns:

Axis orientation.

getCode(){string} proj/Projection.js, line 151

Get the code for this projection, e.g. 'EPSG:4326'.

Returns:

Code.

getExtent(){Extent} proj/Projection.js, line 160

Get the validity extent for this projection.

Returns:

Extent.

getMetersPerUnit(){number | undefined} proj/Projection.js, line 180

Get the amount of meters per unit of this projection. If the projection is not configured with metersPerUnit or a units identifier, the return is undefined.

Returns:

Meters.

getUnits(){Units} proj/Projection.js, line 169

Get the units of this projection.

Returns:

Units.

getWorldExtent(){Extent} proj/Projection.js, line 189

Get the world extent for this projection.

Returns:

Extent.

isGlobal(){boolean} proj/Projection.js, line 213

Is this projection a global projection which spans the whole world?

Returns:

Whether the projection is global.

setExtent(extent) proj/Projection.js, line 246

Set the validity extent for this projection.

Name	Type	Description
`extent`	Extent	Extent.

setGetPointResolution(func) proj/Projection.js, line 267

Set the getPointResolution function (see getPointResolution for this projection.

Name	Type	Description
`func`	function	Function

setGlobal(global) proj/Projection.js, line 222

Set if the projection is a global projection which spans the whole world

Name	Type	Description
`global`	boolean	Whether the projection is global.

setWorldExtent(worldExtent) proj/Projection.js, line 257

Set the world extent for this projection.

Name	Type	Description
`worldExtent`	Extent	World extent [minlon, minlat, maxlon, maxlat].