Crate miniproj

Miniproj

This crate implements geographic coordinate projections between projected coordinate systems and their underlying geographic coordinate systems, for projected coordinate reference systems defined by the European Petroleum Survey Group Geodesy. It was originally developped at the GEOMAR Helmholtz Centre for Ocean Research as part of the Digital Earth Project, and continues to provide reprojection functionality to the Digital Earth Viewer.

The projections are implemented according to the Guidance Notes, with all “dynamically uniform” local variables calculated at compile time. The projections are then stored in a static PHFMap for quick access at runtime. Code generation is split out into the miniproj-epsg-registry crate, while the operations themselves are implemented in miniproj-ops.

Miniproj is not related to or derived from Proj.

Scope

Projections

EPSG Code	Operation Method Name	# of Projected CRS covered
9807	Transverse Mercator	3591
9802	Lambert Conic Conformal (2SP)	949
9801	Lambert Conic Conformal (1SP)	215
9822	Albers Equal Area	36
9809	Oblique Stereographic	20
9820	Lambert Azimuthal Equal Area	14
9810	Polar Stereographic (Variant A)	10
1024	Popular Visualisation Pseudo-Mercator	1

Conversions

EPSG Code	Operation Method Name
9602	Geographic/Geocentric Conversions

Transformations

EPSG Code	Operation Method Name
None	Under Development

Usage example

// Get the WGS84 UTM zone 32N projection
use miniproj::{
    get_projection,
    Projection,
    get_ellipsoid_code,
    get_ellipsoid,
    Ellipsoid
};
let projection = get_projection(32632)
    .expect("Projection not implemented.");

// Coordinates of the office where this crate was written in UTM:
let (easting, northing) = (576935.86f64, 6020593.46f64);

// To get the latitude and longitude, use the Projection::to_deg
// method. Note that the order of the returned tuple is not 
// alphabetical, but instead follows the axis order (X for
// Longitude, Y for Latitude).
let (lon, lat) = projection.projected_to_deg(easting, northing);

assert!((lon - 10.183034).abs() < 0.000001);
assert!((lat - 54.327389).abs() < 0.000001);

// To convert this geographic position to a geocentric position
// (a position in euclidian space), get the underlying ellipsoid:

let ellipsoid = get_ellipsoid_code(32632)
    .and_then(|c| get_ellipsoid(c))
    .expect("No associated ellipsoid.");

// Do the actual conversion. Axis order applies as explained above.
// Height as per GPS altitude.
let (x, y, z) = ellipsoid.deg_to_geocentric(lon, lat, 53.7);

assert!((x - 3668985.10).abs() < 0.1);
assert!((y - 659033.08).abs() < 0.1);
assert!((z - 5158122.64).abs() < 0.1);

Limitations

Miniproj is still under development and missing some important functionality. If you are looking for a refined, proven library, check out PROJ.

Changelog

0.10.0

• Expose constructing projections for a given projection method code. This can be used to create a projection instance for parameter sets or ellipsoids that aren’t part of the EPSG registry.

0.9.0

• Removed Dependency rusqlite
• miniproj can now be built with stable rustc (1.71.0)
• No longer special-case “Identity” Projection, now it allows more geographic coordinate systems to be treated as if they were projected (606 defined CRS)
• For now, filter CRS that do not use the Greenwich Meridian

0.8.0

• Added Albers Equal Area (36 defined CRS)

0.7.0

• Added Oblique Stereographic (20 defined CRS)

0.6.0

• Expose Ellipsoids
• Added an interface to access Ellipsoids by EPSG code
• Added an interface to find the underlying ellipsoid for a projection by EPSG code

0.5.0

• Added Lambert Conic Conformal (1SP) (233 defined CRS)
• Cleared up some terminology

0.4.0

• Added Popular Visualisation Pseudo-Mercator (1 defined CRS). This method might be the most popular, as it is the map projection used by Google, OpenStreetMap etc.

0.3.0

• Added Lambert Conic Conformal (2SP) (950 defined CRS)
• Fixed some major bugs in Polar Stereographic A

0.2.0

• Added Polar Stereographic Method A (10 defined CRS)

0.1.1

• Initial release

Roadmap

Before 1.0.0

• Implement transformations
• Implement refined handling of nonstandard meridians
• Add feature gating for operation methods

Long-Term

• Implement all missing projections
• Implement parsing of WKT and similar
• Make a subset of miniproj no-std
• Add interoperability with crates like geo

License

As many of the other components of the Digital Earth Viewer, Miniproj is licensed under EUPL v1.2, which is a copyleft license similar and compatible to GPLv2 and available in 23 languages. This license does not apply to the projections themselves. The database files are extracts from the EPSG Geodetic Parameter Registry and redistributed under their own Terms of Use.

Structs

• Ellipsoid
  Ellipsoid, a simple approximation of the earth’s shape used in most Projections

Traits

• Projection
  Two-dimensional coordinate operation

Functions

• custom_projection
  Try to construct a projection for a specific method code with a getter that provides the parameter values.
• get_ellipsoid
  Returns the Ellipsoid corresponding to the EPSG code passed as the argument. If the code does not refer to an Ellipsoid, the method returns None.
• get_ellipsoid_code
  Returns the EPSG code of the ellipsoid that is associated with the projection corresponding to projection_code. Returns None if the projection is unknown.
• get_projection
  Returns the Projected Coordinate Reference System corresponding to the EPSG code passed as the argument. If the code refers to a projection that is not implemented, the method returns None