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Rust library for transforming geographic point coordinates from one coordinate system to another. This is a pure Rust implementation of the PROJ.4 project.

The documentation is available on docs.rs and the demo on docs.3liz.org.

Features and Limitations

Basic usage in Rust

Define the coordinate system with proj strings and use the transform function. You can easily get the projection string of any coordinate system from EPSG.io.

Note: Proj4rs use radians as natural angular unit (as does the original proj library)

Example:

use proj4rs;
use proj4rs::proj::Proj;

// EPSG:5174 - Example
let from = Proj::from_proj_string(concat!(
    "+proj=tmerc +lat_0=38 +lon_0=127.002890277778",
    " +k=1 +x_0=200000 +y_0=500000 +ellps=bessel",
    " +towgs84=-145.907,505.034,685.756,-1.162,2.347,1.592,6.342",
    " +units=m +no_defs +type=crs"
))
.unwrap();

// EPSG:4326 - WGS84, known to us as basic longitude and latitude.
let to = Proj::from_proj_string(concat!(
    "+proj=longlat +ellps=WGS84",
    " +datum=WGS84 +no_defs"
))
.unwrap();

let mut point_3d = (198236.3200000003, 453407.8560000006, 0.0);
proj4rs::transform::transform(&from, &to, &mut point_3d).unwrap();

// Note that WGS84 output from this library is in radians, not degrees.
point_3d.0 = point_3d.0.to_degrees();
point_3d.1 = point_3d.1.to_degrees();

// Output in longitude, latitude, and height.
println!("{} {}",point_3d.0, point_3d.1); // 126.98069676435814, 37.58308534678718

WKT support

If you need full support for WKT, please rely on proj which provides a great implementation of the standards.

If you want WKT support in WASM, please have a look at:

Grid shift supports

Nadgrid support is still experimental. Currently, only Ntv2 multi grids are supported for native build and WASM.

JavaScript API

When compiled for WASM, the library exposes JavaScript API that is very similar to that of proj4js. A thin JavaScript layer provides full compatibility with proj4js and thus can be used as a proj4js replacement.

Example:

let from = new Proj.Projection("+proj=latlong +ellps=GRS80");
let to = new Proj.Projection("+proj=etmerc +ellps=GRS80");
let point = new Proj.Point(2.0, 1.0, 0.0);

// Point is transformed in place
Proj.transform(from, to, point);

Contributing

You can contribute to this library by going on the proj4rs repository