Expand description
Pure Rust geographical projections library. Similar to Proj in
basic functionality but allows for a use in concurrent contexts.
Projections’ implementations closely follow algorithms and instructions provided in: Map projections: A working manual (John P. Snyder, 1987)
This crate in very early stages of development. If you are interested in contributing do not hesitate to contact me on Github.
Usage example
We can project the geographical coordinates to cartographic coordinates on a map with sepcified projection as follows:
// First, we define the projection
// We use LCC with reference longitude centered on France
// parallels set for Europe and WGS84 ellipsoid
let lcc = LambertConformalConic::new(2.0, 0.0, 30.0, 60.0, Ellipsoid::wgs84())?;
// Second, we define the coordinates of Mount Blanc
let (lon, lat) = (6.8651, 45.8326);
// Project the coordinates
let (x, y) = lcc.project(lon, lat)?;
// And print the result
println!("x: {}, y: {}", x, y); // x: 364836.4407792019, y: 5421073.726335758We can also inversly project the cartographic coordinates to geographical coordinates:
// We again start with defining the projection
let lcc = LambertConformalConic::new(2.0, 0.0, 30.0, 60.0, Ellipsoid::wgs84())?;
// We take the previously projected coordinates
let (x, y) = (364836.4407792019, 5421073.726335758);
// Inversly project the coordinates
let (lon, lat) = lcc.inverse_project(x, y)?;
// And print the result
println!("lon: {}, lat: {}", lon, lat); // lon: 6.8651, lat: 45.83260000001716Some projections are mathematically exactly inversible, and technically geographical coordinates projected and inverse projected should be identical. However, in practice limitations of floating-point arithmetics will introduce some errors along the way, as shown in the example above.