Struct WebMercatorProjection 

pub struct WebMercatorProjection { /* private fields */ }

Web Mercator / Pseudo Mercator Projection

The Web Mercator / Pseudo Mercator projection is a cylindrical map projection. This is a variant of the regular Mercator projection, except that the computation is done on a sphere, using the semi-major axis of the ellipsoid.

From Wikipedia:

This projection is widely used by the Web Mercator, Google Web Mercator, Spheroidal Mercator, WGS 84 Web Mercator[1] or WGS 84/Pseudo-Mercator is a variant of the Mercator projection and is the de facto standard for Web mapping applications. […] It is used by virtually all major online map providers […] Its official EPSG identifier is EPSG:3857, although others have been used historically.

Classification: Cylindrical (non-conformal if used with an ellipsoid)

Available forms: Forward and Inverse

Defined area: Global

Alias: webmerc

Domain: 2D

Input type: Geodetic coordinates

Output type: Projected coordinates

Usage

$ echo 2 49 | proj +proj=webmerc +datum=WGS84
222638.98       6274861.39

Parameters

Note: All parameters for the projection are optional, except the ellipsoid definition, which is WGS84 for the typical use case of EPSG:3857. In which case, the other parameters are set to their default 0 value.

• ellps: Ellipsoid
• lon_0: Longitude of origin
• x_0: False easting
• y_0: False northing

Mathematical Definition

The formulas describing the Mercator projection are adapted from G. Evenden’s libproj manuals.

Forward Projection:

$$ x = λ $$ $$ y = ln(tan(π/4 + φ/2)) $$

Inverse Projection:

$$ λ = x $$ $$ φ = π/2 - 2 * atan(exp(-y)) $$

Further Reading

• Wikipedia: Web Mercator

Trait Implementations

impl Clone for WebMercatorProjection

fn clone(&self) -> WebMercatorProjection

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl CoordinateStep for WebMercatorProjection

fn new(proj: Rc<RefCell<Proj>>) -> Self

Create a new Converter

fn forward<P: TransformCoordinates>(&self, p: &mut P)

forward conversion

fn inverse<P: TransformCoordinates>(&self, p: &mut P)

inverse conversion

impl Debug for WebMercatorProjection

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for WebMercatorProjection

fn eq(&self, other: &WebMercatorProjection) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl ProjectCoordinates for WebMercatorProjection

fn code(&self) -> i64

ESPG code for this projection

fn name(&self) -> &'static str

Projection name

fn names() -> &'static [&'static str]

Returns the list of canonical names for this projection. This is an associated function, similar to a static method.

fn datum_type() -> u8

get the datum type. Defaults to no datum

impl StructuralPartialEq for WebMercatorProjection