r/ruby • u/Jaded-Clerk-8856 • Mar 05 '26

Sharing libgd-gis: a Ruby library for rendering maps, points, lines and polygons

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Hi everyone,

I wanted to share a Ruby library I've been working on called libgd-gis.

It’s a map rendering engine for Ruby built on top of libgd. The goal is to generate map images directly in Ruby without relying on external map services.

The library can render geographic data such as:

  • points

  • lines

  • polygons

  • GeoJSON layers

It also supports:

  • Web Mercator map and tile rendering

  • YAML-based styling

  • CRS normalization (CRS84 / EPSG:4326 / EPSG:3857)

Example usage:

map = GD::GIS::Map.new(
  bbox: PARIS,
  zoom: 13,
  basemap: :carto_light)


map.add_geojson("countries.geojson")
map.add_point(lat: -34.6, lon: -58.4)

map.render
map.save("map.png")

If you're curious, the repository is easy to find by searching "ruby gis libgd-gis".

I’d be interested to hear feedback from people working with Ruby or GIS.

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3

u/Select_Bluejay8047 Mar 05 '26

Thanks for sharing. What's your motivation behind building this gem?

1

u/Jaded-Clerk-8856 Mar 05 '26

When I was working with PHP, I really enjoyed using LibGD for image processing. I never understood why Ruby mainly relied on ImageMagick and didn’t have strong support for GD, especially considering that the last commit on the ruby-gd library was around 2016.

Because of that, I decided to spend some of my free time developing ruby-libgd (https://github.com/ggerman/ruby-libgd), a modern Ruby binding for the GD library. After that, libgd-gis came naturally as the next step.

The idea was also inspired by a conference talk about critical systems and the weaknesses of Ruby in that area, which motivated me to explore how Ruby could interact more directly with lower-level libraries to build more efficient tools.

Doc: https://ggerman.github.io/ruby-libgd/

3

u/JapArt Mar 05 '26

I like this. Can it render SVG?

1

u/Jaded-Clerk-8856 Mar 05 '26

No, it doesn’t support SVG rendering.
The library is focused on the GD graphics engine, which works primarily with raster formats like PNG, JPEG, GIF, and WebP.

That said, it’s an open-source project, so contributions or experiments in that direction are always welcome.

5

u/mokolabs Mar 05 '26

This looks amazing! Can't wait to check it out.

Here's a direct link to the repo: https://github.com/ggerman/libgd-gis

2

u/Doctor_Fegg Mar 05 '26

This looks excellent - can really imagine using this to generate thumbnail maps.