Coordinate transformation via bindings to the PROJ v8.1.0 API.
Two coordinate transformation operations are currently provided: projection (and inverse projection) and conversion.
Projection is intended for transformations between geodetic and projected coordinates and vice versa (inverse projection), while conversion is intended for transformations between projected coordinate systems. The PROJ documentation explains the distinction between these operations in more detail.
This crate depends on libproj v8.1.x
, accessed via the
proj-sys
crate. By default, proj-sys
will try to find a
pre-existing installation of libproj on your system. If an appropriate version of libproj
cannot be found, the build script will attempt to build libproj from source. You may specify a
from-source build with the bundled_proj
feature.
Out of the box, any (x, y)
numeric tuple can be provided as input to proj. You can conform
your own types to the Coord trait to pass
them in directly and avoid intermediate allocations. There is a geo-types
feature, enabled by default, which implements this trait for types in
the geo-types
crate.
Methods for conversion and
projection of slices of Coord
s are also available.
Convert from NAD 83 US Survey Feet to NAD 83 Meters Using EPSG Codes
use proj::Proj;
let from = "EPSG:2230";
let to = "EPSG:26946";
let ft_to_m = Proj::new_known_crs(&from, &to, None).unwrap();
let result = ft_to_m
.convert((4760096.421921f64, 3744293.729449f64))
.unwrap();
assert_relative_eq!(result.0, 1450880.2910605003);
assert_relative_eq!(result.1, 1141263.0111604529);
Convert from NAD 83 US Survey Feet to NAD 83 Meters Using the pipeline
Operator
Note that as of v5.0.0, PROJ uses the pipeline
operator, which allows an arbitrary number of steps in a conversion. The example below works as
follows:
- define the operation as a
pipeline
operation - define
step
1 as aninv
erse transform, yielding geodetic coordinates - define
step
2 as a forward transform to projected coordinates, yielding metres.
use proj::Proj;
let ft_to_m = Proj::new("
+proj=pipeline
+step +inv +proj=lcc +lat_1=33.88333333333333
+lat_2=32.78333333333333 +lat_0=32.16666666666666
+lon_0=-116.25 +x_0=2000000.0001016 +y_0=500000.0001016001 +ellps=GRS80
+towgs84=0,0,0,0,0,0,0 +units=us-ft +no_defs
+step +proj=lcc +lat_1=33.88333333333333 +lat_2=32.78333333333333 +lat_0=32.16666666666666
+lon_0=-116.25 +x_0=2000000 +y_0=500000
+ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs
").unwrap();
// The Presidio, approximately
let result = ft_to_m.convert((4760096.421921f64, 3744293.729449f64)).unwrap();
assert_relative_eq!(result.0, 1450880.2910605003);
assert_relative_eq!(result.1, 1141263.01116045);
Inverse Projection from Stereo70 to Geodetic
use proj::Proj;
// Carry out an inverse projection from Pulkovo 1942(58) / Stereo70 (EPSG 3844)
// into geodetic lon and lat coordinates (in radians)
let stereo70 = Proj::new("
+proj=sterea +lat_0=46 +lon_0=25 +k=0.99975 +x_0=500000 +y_0=500000
+ellps=krass +towgs84=33.4,-146.6,-76.3,-0.359,-0.053,0.844,-0.84
+units=m +no_defs
").unwrap();
let geodetic_radians_point = stereo70.project(
(500119.70352012233f64, 500027.77896348457f64), true
).unwrap();
assert_relative_eq!(geodetic_radians_point.0, 0.436332, epsilon=1e-5);
assert_relative_eq!(geodetic_radians_point.1, 0.802851, epsiolon=1e-5);
There are two options for creating a transformation:
- If you don't require additional grids or other customisation:
- Call
Proj::new
orProj::new_known_crs
. This creates a transformation instance (Proj
)
- Call
- If you require a grid for the transformation you wish to carry out, or you need to customise
the search path or the grid endpoint:
- Create a new
ProjBuilder
by callingProjBuilder::new()
. It may be modified to enable network downloads, disable the grid, cache or modify search paths; - Call
ProjBuilder.proj()
orProjBuilder.proj_known_crs()
. This creates a transformation instance (Proj
)
- Create a new
Note:
- Both
ProjBuilder
andProj
implement theInfo
trait, which can be used to get information about the current state of thePROJ
instance; Proj::new()
andProjBuilder::proj()
have the same signature;Proj::new_known_crs()
andProjBuilder::proj_known_crs()
have the same signature.
By default, the crate requires libproj
8.1.x to be present on your system. While it may be
backwards-compatible with older PROJ 6 versions, this is neither tested nor supported.
geo-types
: include trait impls forgeo-types
. See example.pkg_config
: enables the use ofpkg-config
when linking againstlibproj
— note thatpkg-config
must be available on your system.bundled_proj
: buildslibproj
from source bundled in theproj-sys
crate. Note that this feature requires Sqlite3 andlibtiff
to be present on your system.network
: exposes APIs which, when enabled, can fetch grid data from the internet to improve projection accuracy. Seeenable_network
for details.
proj
supports network grid download functionality via
the network
feature. Network access is disabled by default, and can be
activated by passing a true
bool
to
enable_network()
. Network
functionality status can be queried with network_enabled
, and the download endpoint can be
queried and set using get_url_endpoint
and set_url_endpoint
.
Up to 300 mb of downloaded grids are cached to save bandwidth: This cache can be enabled or
disabled using grid_cache_enable
.
The path used to search for resource files can be modified using
set_search_paths
If you have your own geometric types, you can conform them to the Coord
trait and use proj
without any intermediate allocation.
use proj::{Proj, Coord};
struct MyPointOfInterest {
lat: f64,
lon: f64,
}
impl Coord<f64> for MyPointOfInterest {
fn x(&self) -> f64 {
self.lon
}
fn y(&self) -> f64 {
self.lat
}
fn from_xy(x: f64, y: f64) -> Self {
Self { lon: x, lat: y }
}
}
let donut_shop = MyPointOfInterest { lat: 34.095620, lon: -118.283555 };
let from = "EPSG:4326";
let to = "EPSG:3309";
let proj = Proj::new_known_crs(&from, &to, None).unwrap();
let result = proj.convert(donut_shop).unwrap();
assert_relative_eq!(result.x(), 158458.67251293268);
assert_relative_eq!(result.y(), -434296.8803996085);
If you've enabled the geo-types
feature, you can skip allocating an intermediate representation,
and pass the geo-types
directly.
# use approx::assert_relative_eq;
use proj::Proj;
use geo_types::Point;
let my_point = Point::new(4760096.421921f64, 3744293.729449f64);
let from = "EPSG:2230";
let to = "EPSG:26946";
let nad_ft_to_m = Proj::new_known_crs(&from, &to, None).unwrap();
let result = nad_ft_to_m.convert(my_point).unwrap();
assert_relative_eq!(result.x(), 1450880.2910605003f64);
assert_relative_eq!(result.y(), 1141263.0111604529f64);
License: MIT/Apache-2.0