LibGD-GIS

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A geospatial raster engine for Ruby.

libgd-gis allows Ruby to render real maps, GeoJSON layers, vector features, and geospatial tiles using a native raster backend powered by libgd.

It restores something Ruby lost over time: the ability to generate maps, tiles, and GIS-grade visualizations natively, without relying on external tools like QGIS, Mapnik, ImageMagick, or Mapbox.

Built on top of ruby-libgd, this project turns Ruby into a map rendering engine, capable of producing spatial graphics, tiled maps, and geospatial outputs directly inside Ruby processes.

  • No external renderers.
  • No shelling out.
  • Just Ruby, raster, and GIS.

What is this?

libgd-gis is a geospatial rendering engine for Ruby built on top of ruby-libgd.

It allows you to:

  • Load GeoJSON, CSV, or any dataset with coordinates
  • Fetch real basemap tiles
  • Reproject WGS84 (lat/lon) into Web Mercator
  • Render points, icons, and layers onto a raster map
  • Generate PNG maps or map tiles

This is the same type of pipeline used by professional GIS systems — implemented in Ruby.

Installation

System dependency

libgd-gis depends on libgd, via ruby-libgd.

Install libgd first:

Ubuntu / Debian

sudo apt install libgd-dev

macOS

brew install gd

Ruby gems

gem install ruby-libgd
gem install libgd-gis

Quick Example

Render hydroelectric plants from a GeoJSON file:

require "json"
require "gd/gis"

# ---------------------------
# Bounding box mundial
# ---------------------------
AMERICA = [-170, -60, -30, 75]

# ---------------------------
# Crear mapa
# ---------------------------
map = GD::GIS::Map.new(
  bbox: AMERICA,
  zoom: 4,
  basemap: :carto_light
)

# Cargar datos
# ---------------------------
peaks = JSON.parse(File.read("picks.json"))

# ---------------------------
# Agregar capa de puntos
# ---------------------------
map.add_points(
  peaks,
  lon: ->(p) { p["longitude"] },
  lat: ->(p) { p["latitude"] },
  icon: "peak.png",
  label: ->(p) { p["name"] },
  font: "./fonts/DejaVuSans.ttf",
  size: 10,
  color: [0,0,0]
)

# ---------------------------
# Renderizar y guardar
# ---------------------------
map.render
map.save("output/america.png")

puts "Saved output/america.png"

Features

  • Real basemap tiles
  • WGS84 → Web Mercator projection
  • GeoJSON point rendering
  • CSV / JSON support
  • Icon-based symbol layers
  • Automatic bounding box fitting
  • Raster output (PNG)

License

MIT

Author

Germán Silva https://github.com/ggerman https://rubystacknews.com