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qgis-rs

crs

qgis_render::crs

Coordinate reference systems and the transforms between them, backed by PROJ through QGIS.

use qgis_render::crs::*;

Contents

ItemDescription
CrsA coordinate reference system.
CoordTransformA reusable transform between two CRS.
CrsErrorFailure type, surfaced as QgisError::CrsError.

CoordTransform

Build once, use many times — construction resolves a PROJ pipeline, which costs far more than an individual transform.

let wgs84 = Crs::from_epsg(4326)?;
let mercator = Crs::from_epsg(3857)?;
let transform = CoordTransform::new(&wgs84, &mercator)?;


let (x, y) = transform.transform(14.0, 50.0)?;


let many = transform.transform_batch(&[
    (14.0, 50.0),
    (15.0, 51.0),
    (16.0, 52.0),
])?;
MethodReturnsDescription
new(&Crs, &Crs)Result<CoordTransform, QgisError>Resolve the pipeline between two CRS.
transform(x, y)Result<(f64, f64), QgisError>Transform one coordinate.
transform_batch(&[(f64, f64)])Result<Vec<(f64, f64)>, QgisError>Transform many at once.
transform_z(x, y, z)Result<(f64, f64, f64), QgisError>Transform with elevation, when the pipeline is 3D.
source() / target()&CrsThe two ends of the transform.

Transforming geometries

For anything more than single coordinates, transform the geometry — it handles every vertex and densifies where a straight line in one CRS is curved in the other.

let reprojected = geom.transform(&wgs84, &mercator)?;

Axis order

QGIS and PROJ use x, y (longitude, latitude) internally regardless of the CRS’s declared axis order. WMS 1.3 GetMap requests, in contrast, use latitude/longitude for geographic CRS — the wms module handles that translation for you.

See also