--- layout: api title: "v2.0.1 JavaScript Library: L.ICRS" categories: api version: v2.0.1 permalink: /api/v2.0.1/l-icrs ---

## ICRS

Defines coordinate reference systems for projecting geographical points into pixel (screen) coordinates and back (and to coordinates in other units for WMS services). See Spatial reference system.

### Methods

Method | Returns | Description
--- | --- | ---
`latLngToPoint( <LatLng> latlng, <Number> zoom )` | `Point` | Projects geographical coordinates on a given zoom into pixel coordinates.
`pointToLatLng( <Point> point, <Number> zoom )` | `LatLng` | The inverse of `latLngToPoint`. Projects pixel coordinates on a given zoom into geographical coordinates.
`project( <LatLng> latlng )` | `Point` | Projects geographical coordinates into coordinates in units accepted for this CRS (e.g. meters for `EPSG:3857`, for passing it to WMS services).
`scale( <Number> zoom )` | `Number` | Returns the scale used when transforming projected coordinates into pixel coordinates for a particular zoom. For example, it returns `256 * 2^zoom` for Mercator-based CRS.
`getSize( <Number> zoom )` | `Point` | Returns the size of the world in pixels for a particular zoom.

### Properties

Property | Type | Description
--- | --- | ---
`projection` | `IProjection` | Projection that this CRS uses.
`transformation` | `Transformation` | Transformation that this CRS uses to turn projected coordinates into screen coordinates for a particular tile service.
`code` | `String` | Standard code name of the CRS passed into WMS services (e.g. `'EPSG:3857'`).

### Defined CRS

Leaflet comes with a set of already defined CRS to use out of the box:

Projection | Description
--- | ---
`L.CRS.EPSG3857` | The most common CRS for online maps, used by almost all free and commercial tile providers. Uses Spherical Mercator projection. Set in by default in Map's `crs` option.
`L.CRS.EPSG4326` | A common CRS among GIS enthusiasts. Uses simple Equirectangular projection.
`L.CRS.EPSG3395` | Rarely used by some commercial tile providers. Uses Elliptical Mercator projection.
`L.CRS.Simple` | A simple CRS that maps longitude and latitude into `x` and `y` directly. May be used for maps of flat surfaces (e.g. game maps). Note that the `y` axis should still be inverted (going from bottom to top).

If you want to use some obscure CRS not listed here, take a look at the Proj4Leaflet plugin.