libgd-gis
libgd-gis — Static Map Rendering for Ruby
libgd-gis is a static GIS rendering engine for Ruby, built on top of
ruby-libgd and the GD Graphics Library.
It transforms geospatial data (GeoJSON, coordinates, layers) into
high-quality raster images, with full control over styling, overlays
and post-processing.
It is not an interactive map library.
It is a map renderer.
Rendering Pipeline
libgd-gis follows a clear and explicit rendering pipeline:
- Define viewport and bounding box
- Load a basemap
- Apply a style (YAML)
- Add geographic layers (GeoJSON or overlays)
- Render the map
- Post-process the image with ruby-libgd
Viewport & Map Setup
| File | Description |
|---|---|
new.md |
Define bounding boxes, zoom levels, image size, and automatic fitting |
This section explains how to control what part of the world is rendered and at what resolution.
Styles (YAML)
| File | Description |
|---|---|
styles.md |
YAML-based styling system for roads, water, parks, rails, points |
Styles are declarative, reusable, and fully separated from code.
GeoJSON Layers
| File | Description |
|---|---|
add_geojson.md |
Load and render GeoJSON files as map layers |
Overlays (Programmatic Geometry)
Overlays are explicit geometries defined in code, not in GeoJSON files.
| File | Description |
|---|---|
add_points.md |
Render points, POIs, labels and markers |
add_lines.md |
Render routes, tracks and line strings |
add_polygons.md |
Render polygons and areas with fill and alpha |
Post-Render Image Access
| File | Description |
|---|---|
map_image.md |
Access the rendered GD::Image and manipulate it |
After rendering, the map becomes a GD::Image and can be modified using
the full ruby-libgd API.
Design Philosophy
- Geospatial logic → libgd-gis
- Image manipulation → ruby-libgd
Stability Notice
libgd-gis evolves quickly.
Please report issues:
- https://github.com/ggerman/libgd-gis/issues
- ggerman@gmail.com