https://github.com/locationtech/proj4j
Java port of the Proj.4 library for coordinate reprojection
https://github.com/locationtech/proj4j
geodesy gis java proj4j projection
Last synced: 7 months ago
JSON representation
Java port of the Proj.4 library for coordinate reprojection
- Host: GitHub
- URL: https://github.com/locationtech/proj4j
- Owner: locationtech
- License: other
- Created: 2017-10-16T18:27:26.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2025-03-31T15:47:52.000Z (8 months ago)
- Last Synced: 2025-04-14T23:16:27.347Z (8 months ago)
- Topics: geodesy, gis, java, proj4j, projection
- Language: Java
- Homepage:
- Size: 2.09 MB
- Stars: 198
- Watchers: 15
- Forks: 74
- Open Issues: 27
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
Awesome Lists containing this project
- Awesome-Geospatial - Proj4j - Java port of the Proj.4 library for coordinate reprojection. (Java)
README
# Proj4J [](https://github.com/locationtech/proj4j/actions) [](https://search.maven.org/search?q=g:org.locationtech.proj4j%20AND%20a:proj4j)
Proj4J is a Java library for converting coordinates between different geospatial coordinate reference systems.
It is designed to be compatible with `proj.4` parameters and derives some of its implementation from the `proj.4` sources.
Proj4J is a project in the [LocationTech](http://www.locationtech.org) working group of the Eclipse Foundation.
## User Guide
Proj4J artifacts are available on maven central.
**!Important!** As of `1.2.2` version, `proj4-core` contains no EPSG Licensed files.
In order to make proj4j properly operate, it makes sense to consider `proj4-epsg` dependency usage.
### Using Proj4J with Maven
To include Proj4J in a Maven project, add a dependency block like the following:
```xml
{latest version}
org.locationtech.proj4j
proj4j
${proj4j.version}
```
where `{latest version}` refers to the version indicated by the badge above.
#### Proj4j EPSG
`Proj4J-EPSG` module distributes a portion of the EPSG dataset. This artifact is released the [EPSG database distribution license](https://raw.githubusercontent.com/locationtech/proj4j/master/LICENSE.EPSG).
To include `Proj4J-EPSG` in a Maven project, add a dependency block like the following:
```xml
{latest version}
org.locationtech.proj4j
proj4j-epsg
${proj4j.version}
```
where `{latest version}` refers to the version indicated by the badge above.
#### Using Proj4j with GeoAPI
`Proj4j-GeoAPI` module provides wrappers for using Proj4J behind [GeoAPI](https://www.geoapi.org/) interfaces.
GeoAPI is a set of Java interfaces derived from OGC/ISO standards
for using different implementations of metadata and referencing services through a standard API.
To include the module in a Maven project, add a dependency block like the following:
```xml
{latest version}
org.locationtech.proj4j
proj4j-geoapi
${proj4j.version}
```
where `{latest version}` refers to the version indicated by the badge above.
Usage examples are available on the [GeoAPI site](https://www.geoapi.org/java/examples/usage.html).
### Using Proj4J with Gradle
To include Proj4J in a Gradle project, add a dependency block like the following:
```
dependencies {
implementation 'org.locationtech.proj4j:proj4j:{latest version}'
}
```
where `{latest version}` refers to the version indicated by the badge above.
#### Proj4j EPSG
`Proj4J-EPSG` module distributes a portion of the EPSG dataset. This artifact is released the [EPSG database distribution license](https://raw.githubusercontent.com/locationtech/proj4j/master/LICENSE.EPSG).
To include `Proj4J-EPSG` in a Gradle project, add the following line to the dependency block:
```
implementation 'org.locationtech.proj4j:proj4j-epsg:{latest version}'
```
where `{latest version}` refers to the version indicated by the badge above.
#### Using Proj4j with GeoAPI
`Proj4j-GeoAPI` module provides wrappers for using Proj4J behind [GeoAPI](https://www.geoapi.org/) interfaces.
GeoAPI is a set of Java interfaces derived from OGC/ISO standards
for using different implementations of metadata and referencing services through a standard API.
To include the module in a Gradle project, add the following line to the dependency block:
```
implementation 'org.locationtech.proj4j:proj4j-geoapi:{latest version}'
```
where `{latest version}` refers to the version indicated by the badge above.
Usage examples are available on the [GeoAPI site](https://www.geoapi.org/java/examples/usage.html).
### Basic Usage
The following examples give a quick intro on how to use Proj4J in common
use cases.
#### Transforming coordinates from WGS84 to UTM
##### Obtaining CRSs by name
```Java
CRSFactory crsFactory = new CRSFactory();
CoordinateReferenceSystem WGS84 = crsFactory.createFromName("epsg:4326");
CoordinateReferenceSystem UTM = crsFactory.createFromName("epsg:25833");
```
##### Obtaining CRSs using parameters
```Java
CRSFactory crsFactory = new CRSFactory();
CoordinateReferenceSystem WGS84 = crsFactory.createFromParameters("WGS84",
"+proj=longlat +datum=WGS84 +no_defs");
CoordinateReferenceSystem UTM = crsFactory.createFromParameters("UTM",
"+proj=utm +zone=33 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs");
```
##### Transforming coordinates
```Java
CoordinateTransformFactory ctFactory = new CoordinateTransformFactory();
CoordinateTransform wgsToUtm = ctFactory.createTransform(WGS84, UTM);
// `result` is an output parameter to `transform()`
ProjCoordinate result = new ProjCoordinate();
wgsToUtm.transform(new ProjCoordinate(lon, lat), result);
```
## Building, Testing and installing locally
`mvn clean install`
## Publish to Maven Central
`mvn -Dmaven.test.skip=true -Pcentral clean package deploy`
For more details see [HOWTORELEASE.txt](./HOWTORELEASE.txt).
## Contributing
If you are interested in contributing to Proj4J please read the [**Contributing Guide**](CONTRIBUTING.md).