D3.js Geo

D3.js Geo (d3-geo) is a module within the D3.js ecosystem that provides the building blocks for geographic visualization. At its core are over 50 map projections—from Mercator and Albers to more exotic options like Bertin, Hammer, and interrupted projections—each mathematically transforming latitude and longitude into screen coordinates. The geoPath generator converts GeoJSONGeoJSONGeoJSON is an open standard format for encoding geographic data structures using JavaScript Object Notation (JSON). I... geometries into SVG path strings or Canvas drawing commands, while spherical math utilities compute distances, areas, centroids, and bounding boxes on the globe. D3 Geo is not a turnkey mapping library like LeafletLeafletLeaflet is a lightweight, mobile-friendly JavaScript library for building interactive mapping applications. Known for... or MapboxMapboxMapbox is a robust platform that equips developers with tools to create highly customizable, interactive maps for web... GL JS; instead, it provides low-level primitives that developers compose with D3’s data-binding, scales, axes, and transitions to build fully custom visualizations. This makes it the tool of choice for data journalists, researchers, and designers who need fine-grained control over every visual element. Iconic examples include interactive globe projections, animated migration flows, and zoomable choropleth maps that transition smoothly between projections. Because D3 Geo renders to SVG or Canvas, performance depends on feature count and complexity. For maps with thousands of features, Canvas rendering or simplification with topojson is recommended. The companion d3-geo-projection package extends the available projections, and d3-geo-voronoi adds spherical Voronoi diagramVoronoi DiagramA Voronoi diagram is a geometric partition of space into regions based on distance to a set of generating points, whe... support. D3 Geo’s projection flexibility and integration with the broader D3 ecosystem make it unmatched for bespoke cartographic work on the web.