maplibre-terrain-rendering

MapLibre Terrain Rendering

A raster-dem source is elevation, not a picture. Four different things draw it, each with its own layer type or API, and most of the wrong answers here are Mapbox GL JS properties that MapLibre never had.

When to Use This Skill

These are symptoms as you would observe them, before you know the cause:

• Harsh hillshade contrast: black-and-white ridges, blown-out slopes, chalky valleys — or several hillshade layers stacked to soften them (one layer with hillshade-method: "multidirectional").
• Dynamic elevation coloring: the map needs coloring by height, client-side, with no pre-rendered tiles (a color-relief layer over ["elevation"], not raster-color on a raster layer).
• Runtime contour lines: contour lines straight from a raster-dem source, with no pre-generated contour tileset (maplibre-contour, not a hand-rolled marching-squares pipeline).
• Flat 3D terrain: map.setTerrain() is on and nothing extrudes (the camera is at pitch: 0, and raising exaggeration will not fix it).
• Blank horizon: pitching the camera shows empty page background above the terrain (no root-level sky object or map.setSky(); there is no type: "sky" layer in MapLibre).
• Silent property failures: a hillshade, sky, or terrain-coloring property does nothing and raises no error (a Mapbox GL JS property MapLibre never had).
• Terrain lag or frame drops: stutter when panning or tilting with terrain on (stacked hillshade passes, dense draped layers).

Not this skill. Elevation values that are wrong, spiky, or inverted, choosing an elevation tileset, encoding, and generating DEM tiles — the style specification's raster-dem source page, https://maplibre.org/maplibre-style-spec/sources/#raster-dem. Where hillshade sits among the other layers of a style — maplibre-cartography.

Which one you want

All four read the same raster-dem source; one source can serve all of them.

Hillshade, and the harshness fix that is not stacking

Every hillshade-* property is a paint property.[1] The defaults that matter: hillshade-exaggeration 0.5, hillshade-illumination-direction 335, hillshade-illumination-anchor viewport (the light is fixed to the top of the screen, so it does not turn with the map's bearing unless you set map), hillshade-shadow-color #000000, hillshade-highlight-color #FFFFFF.

Harsh output usually comes from the shading method, not the colors. hillshade-method (GL JS 5.5) takes standard (the default), basic, combined, igor, and multidirectional.[1] multidirectional lights the surface from several independent directions in one pass and igor minimizes the effect on the map features drawn beneath it; both soften terrain on a single layer.

{
  "id": "hillshade",
  "type": "hillshade",
  "source": "terrain-dem",

Do not stack several hillshade layers at different illumination directions. It was the only way to get multi-directional shading before 5.5; since then it is one paint property against N extra draw passes over the same DEM. Pure black shadows and pure white highlights are the other harshness lever: give both an alpha, and use warm highlights with cool shadows over imagery.

Color-relief: coloring by height

color-relief (GL JS 5.6) colors a raster-dem source directly, client-side; there is no pre-rendering step and no raster layer involved. Its paint properties are color-relief-color, color-relief-opacity (default 1), and, from GL JS 5.20, resampling.[1] The ramp is an interpolate expression over ["elevation"], which returns meters above the DEM's vertical datum and is only valid inside color-relief-color.[2]

MapLibre has no raster-color, raster-value, or raster-color-mix; those belong to another renderer and will be dropped as unknown properties. A raster layer pointed at a DEM shows packed RGB, not a tint.

Contours at runtime

maplibre-contour derives vector contour tiles in a Web Worker from the same DEM tiles and serves them through a registered protocol — no contour tileset to build.[3]

thresholds maps zoom to [minor, major] intervals in meters; level is 1 on major contours, which is what the line width and any label layer key on.[3] The encoding here must match the DEM exactly as it does on the style source.

3D terrain, the camera, and the sky

• terrain takes only source and exaggeration (default 1).[4] It is a root-level style object, set in the style or through map.setTerrain(); map.setTerrain(null) turns it off.
• Pitch is what makes it visible. At pitch: 0 an extruded surface is seen straight down and reads as flat. Set pitch on the map (or map.easeTo({ pitch: 60 })) before concluding the terrain is broken — and raise exaggeration only after the camera is tilted, never as the fix for a flat-looking map.
• There is no sky layer type in MapLibre. The layer types are fill, line, symbol, circle, heatmap, fill-extrusion, raster, hillshade, color-relief, and background.[1] Sky is a root-level sky object, or map.setSky(): sky-color, horizon-color, fog-color, sky-horizon-blend, horizon-fog-blend, fog-ground-blend, atmosphere-blend.[5] sky-type, sky-atmosphere-sun, and sky-atmosphere-sun-intensity are Mapbox GL JS properties and do nothing here. fog-color requires 3D terrain.[5]
• map.queryTerrainElevation(lngLat) returns the elevation under a location once terrain is on.[6]

Cost. Terrain decodes DEM tiles, builds a mesh, and re-draws every layer draped over it, so it is the most expensive thing on this page — noticeably so at high zoom and pitch on low-end devices. Keep the terrain stack small: one shared raster-dem source, one or two elevation layers, and only the overlays you need.

Related Skills

• maplibre-cartography — Where a hillshade layer belongs in the layer order, and palettes that survive over relief.
• maplibre-pmtiles-patterns — Serving DEM and imagery tiles from a single PMTiles file.

References

1. Style Specification: layers — hillshade and color-relief paint properties, defaults, hillshade-method values, and the complete list of layer types — https://maplibre.org/maplibre-style-spec/layers/
2. Style Specification: expressions — ["elevation"], valid only in color-relief-color — https://maplibre.org/maplibre-style-spec/expressions/
3. maplibre-contour — DemSource, setupMaplibre, contourProtocolUrl — https://github.com/onthegomap/maplibre-contour
4. Style Specification: terrain — https://maplibre.org/maplibre-style-spec/terrain/
5. Style Specification: sky — https://maplibre.org/maplibre-style-spec/sky/
6. GL JS Map API — setTerrain, setSky, queryTerrainElevation — https://maplibre.org/maplibre-gl-js/docs/API/classes/Map/
7. Examples — 3D terrain, sky, fog, terrain, color relief, contour lines, multidirectional hillshade

This skill is a snapshot. Where a primary source contradicts it — the References above, MapLibre's current documentation, or what MapLibre does when you run it — that source wins. Follow it, then report the disagreement, citing the source and your MapLibre version: editing your installed copy helps no one else and is overwritten on the next update.