A Go library for geospatial operations

The library is basically written as a wrapper around liblwgeom which comes with PostGIS. Liblwgeom uses following libraries in order to perform geospatial calculations.

• GEOS
• liblwgeom
• proj.4

The library containes some extra functions which uses libgeos directly.

Install required libraries on Ubuntu

Using package manager

# Add ubuntugis repository
sudo apt-add-repository -y ppa:ubuntugis/ubuntugis-unstable
sudo apt-get install libgeos-dev libgeos-3.7.0 liblwgeom-2.5-0 liblwgeom-dev libproj-dev

Compile GEOS from source

You can download the source code from https://trac.osgeo.org/geos/.

More on: https://trac.osgeo.org/geos#BuildandInstall

Building GEOS requires a C++11 compiler

# Install gcc and cmake
sudo apt install gcc
sudo apt install cmake

Below are the compilation steps

# Commpilation
wget http://download.osgeo.org/geos/geos-3.7.1.tar.bz2
tar xvfj geos-3.7.1.tar.bz2
cd geos-3.7.1
mkdir build && cd build
cmake ..
make
make check

# Installation. Should be executed with superuser privileges
sudo make install

# Create necessary links
sudo ldconfig

Quick Start

package main

import (
	"fmt"
	"github.com/srimaln91/go-geom/geom"
)

func main() {

	jsonLineString := `{
    "type": "LineString",
    "coordinates": [
            [79.86064,6.933669],
            [79.87326,6.923529],
            [79.87017,6.910237],
            [79.88305,6.899671],
            [79.89008,6.890724],
            [79.89051,6.882118],
            [79.88854,6.869762],
            [79.87532,6.863541]
        ]
    }`

    lwgeom, err := geom.FromGeoJSON(jsonLineString)
    if err != nil {
        fmt.Println(err)
        return
    }

	lwgeom.SetSRID(4326)
	defer lwgeom.Free()

	lwgeom.LineSubstring(0.5, 0.9)

	fromSRS := geom.SRS["EPSG:4326"]
	toSRS := geom.SRS["EPSG:3857"]

	// Transform the geometry to SRS EPSG:3757 so we can measure from metres.
	lwgeom.Project(fromSRS, toSRS)
	lwgeom.Buffer(200)

	// Reset SRS to EPSG:4326
	lwgeom.Project(toSRS, fromSRS)

	bufJSON, err := lwgeom.ToGeoJSON(4, 0)
    if err != nil {
        fmt.Println(err)
        return
    }
    
	fmt.Println(bufJSON)
}