https://github.com/CandyGumdrop/proj

Elixir coordinate conversion library using OSGeo's PROJ.4
https://github.com/CandyGumdrop/proj

c coordinate-systems distance-calculation elixir geospatial osgeo-proj

Last synced: 4 days ago
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Elixir coordinate conversion library using OSGeo's PROJ.4

• Host: GitHub
• URL: https://github.com/CandyGumdrop/proj
• Owner: CandyGumdrop
• License: cc0-1.0
• Created: 2016-08-02T10:30:36.000Z (over 8 years ago)
• Default Branch: develop
• Last Pushed: 2021-01-13T17:53:22.000Z (almost 4 years ago)
• Last Synced: 2024-10-02T07:17:27.981Z (about 1 month ago)
• Topics: c, coordinate-systems, distance-calculation, elixir, geospatial, osgeo-proj
• Language: C
• Size: 27.3 KB
• Stars: 8
• Watchers: 2
• Forks: 6
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: COPYING

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README

        
# Proj

Proj is an Elixir library for converting coordinates between different

coordinate systems, using Erlang NIFs to the OSGeo PROJ.4 library.

Proj also supports geodesic functions from PROJ.4.  A geodesic is the shortest

line around the globe which crosses through two points.  This is useful for

solving problems such as:

- Finding the distance between two locations

- Finding the bearings between two locations

- Finding the resulting location after moving `x` metres forwards facing a

  certain bearing from a given location

- Plotting a set of points in a line between two locations

## Installation

Before you can install Proj, you must have:

- gcc

- PROJ.4 newer than 4.9.0 (PROJ 5+ should work, but this library makes use of

  the legacy PROJ.4 API.)

### Ubuntu / Debian:

    apt install libproj-dev gcc binutils libc-dev make

### Red Hat / CentOS

    yum install proj-devel binutils gcc glibc-devel make

### macOS

    brew install proj

Proj has currently only been tested on GNU/Linux and Mac OS X.  Windows support

has not yet been tested and may require some small changes to work under a

Cygwin or MinGW environment.

## Example Usage

```elixir

iex> {:ok, bng} = Proj.from_epsg(27700) # British National Grid CRS is EPSG:27700

{:ok, #Proj<+init=epsg:27700 ...>}

# Convert the British National Grid Easting + Northing of Buckingham Palace into

# a Latitude + Longitude pair

iex> Proj.to_lat_lng!({529155, 179699}, bng)

{51.50147938477216, -0.1406319210455952}

# Convert the Latitude + Longitude of Buckingham Palace to its

# British National Grid Easting + Northing

iex> Proj.from_lat_lng!({51.501479, -0.140631}, bng)

{529155.0658918166, 179698.9583449281}

# Calculate the shortest distance "as the crow flies" in metres between

# Buckingham Palace and the Eiffel Tower

iex> Proj.Geodesic.distance({51.501476, -0.140634}, {48.8584, 2.2945})

341549.6819692767

# Calculate the resulting location after travelling 100 metres forwards from

# Buckingham Palace, facing a bearing of 060°

iex> Proj.Geodesic.travel({51.501476, -0.140634}, 60, 100)

{51.50192539979596, -0.1393868003258145}

```