What is ezu?

ezu (絵図 — “picture map”) renders vector tiles to raster tiles on the CPU. It is a Rust library, a CLI, and a WebAssembly module. There is no GPU in the pipeline and no headless browser.

Two things make it unusual.

A style is a typed node graph, not a layer list. Instead of an ordered list of layers with paint properties, an ezu style is a DAG of ~80 ops — sources, rasterization, blending, warp, morphology, dither, terrain, text — wired by reference. That is what makes painterly output tractable: a watercolour wash is a scatter-dab fill blurred, blended and warped, which is a graph, not a layer property.

It speaks MapLibre where it counts. ezu translate lowers a MapLibre GL style into an ezu recipe, and any node field that varies per feature accepts a raw MapLibre expression, evaluated by maplibre-expr at 100 % conformance against MapLibre’s official spec fixtures. You can start from an existing basemap style and stay compatible.

Compared to

MapLibre GL JS / native. MapLibre draws on the GPU, per frame, for an interactive viewport. ezu draws on the CPU, per tile, and hands you a PNG. Use MapLibre for a map a user pans; use ezu to produce tiles — for a server, a batch job, a print export, or a stylized basemap you serve like any other raster pyramid. ezu’s label collision is deterministic in world space rather than viewport-driven, which is what makes tiles cacheable but also means there are no per-frame fades or viewport-centre priority.

A conventional raster tile server (Mapnik, MapServer, …). Same output shape, different styling model. ezu’s node graph and brush engine target painterly rendering, and its MapLibre frontend means the style you already have is an input.

Static map images. ezu renders single tiles, bbox mosaics, and whole XYZ pyramids, so a one-off image and a pyramid are the same tool with different flags.

When it is a good fit

• You want a map that looks hand-painted, not styled.
• You need raster tiles from a MapLibre style without keeping a headless browser alive.
• You want rendering inside a process with no GPU — a Worker, a serverless function, a wasm sandbox, a batch pipeline.
• You care that adjacent tiles agree: brush texture, dab placement, and label collision are all deterministic across tile boundaries.

When it is not

• You need an interactive, continuously-zooming client map. Render tiles with ezu and let MapLibre or any raster client display them.
• You need pixel-identical MapLibre output. ezu gets close — a 68-layer Protomaps theme scores SSIM 0.80–0.87 against maplibre-gl-js, labels and icons in place (see the tiles) — but it is a different renderer; see gaps and differences.
• You need true 3-D (fill-extrusion height, terrain meshes). Footprints render flat.

Where to go next

• Install, then render your first tile.
• The node graph for the model behind the style language.
• From a MapLibre style if you already have a style.