Crate proj4rs

source ·
Expand description

Coordinate transformation library

Based on Proj4 implementation

References:

The aim of Proj4rs is to provide at short term the same functionality as the original proj4 library.

The long term project is to integrate feature from the proj library in its latest version.

The goal of proj4rs is not to be a remplacement of proj, but instead being a light weight implementation of transformations from crs to crs that could be used in WASM environment

Usage

Note that angular units are in radians, not degrees !

Radian is natural unit for trigonometric opérations, like proj, proj4rs use radians for its operation while degrees are mostly used as end user input/output.

Example:

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();

// XXX Note that angular unit is 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

Optional features

  • geo-types: geo-types support
  • logging: support for logging with log crate. If activated for WASM, it will use the console-log adaptor.
  • wasm-strict: used with WASM; Transformation operation will return exception as soon as we have invalid coordinates or that the reprojection failed. The default is to use a relaxed-mode that return NaN in case of projection failure: this is expected mostly from js app (at least with OpenLayer).
  • multi-thread: Support for multi-thread with NAD Grid processing, this is activated by default and disabled when compiling for WASM.

WKT Support

There is no actual default support for WKT in proj4rs If you are looking for WTK/Proje string conversion support in Rust, then have a look at:

Note that the proj library provides a great implementation of the standard.

Grid shift supports

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

Re-exports

Modules

  • adaptors
    Transform adaptors
  • errors
    Crate errors
  • nadgrids
    Handle Nadgrids
  • proj
    Projection installation
  • projections
    Implemented projections
  • transform
    Overall coordinate system to coordinate system transformations including reprojection and datum shifting