Raster DEM Source

A raster-dem source describes RGB-encoded elevation tiles. It powers both:

terrain meshing — via a terrain layer, and
hillshade / elevation-heatmap — via a raster layer (the layer supplies the hillshade / elevationHeatmap render options).

The RGB→height decoding is configured by elevationDecoder.

Properties

Property	Type	Default	Description
`type`	`"raster-dem"`	(required)	Source type.
`url`	`string`	(required)	Tile URL template (contains `{z}/{x}/{y}`).
`tms`	`boolean`	`false`	Whether the tile scheme is flipped along the Y axis (TMS).
`elevationDecoder`	`ElevationDecoder`	default decoder	How RGB channels decode into a height value.
`tileSize`	`number`	`256`	Pixel size of a DEM tile.
`minZoom`	`number`	`0`	Minimum zoom level tiles are provided for.
`maxZoom`	`number`	`20`	Maximum zoom level new tiles are requested for.
`overscaledMaxZoom`	`number`	`24`	Maximum zoom overscaled tiles are used up to.

Examples

import ThreeView, { TERRARIUM_ELEVATION_DECODER } from "@navaramap/three";

const dem = view.addSource({
  type: "raster-dem",
  url: "https://example.com/dem/{z}/{x}/{y}.png",
  elevationDecoder: TERRARIUM_ELEVATION_DECODER(),
  tileSize: 512,
  maxZoom: 17,
});

// As 3D terrain
view.addLayer({ type: "terrain", source: dem });

// As a hillshade raster layer (same source reused)
view.addLayer({ type: "raster", source: dem, hillshade: { exaggeration: 1.5 } });

Elevation Decoder

The elevationDecoder describes how the tile’s RGB(A) channels decode into a height value.

Pre-defined constants

@navaramap/three provides decoder constants for common elevation tile providers:

Constant	Use case
`JAPAN_GSI_ELEVATION_DECODER()`	Japan’s Geospatial Information Authority (GSI) elevation tiles
`MAPBOX_ELEVATION_DECODER()`	Mapbox Terrain-RGB tiles
`TERRARIUM_ELEVATION_DECODER()`	Terrarium format elevation tiles

import ThreeView, { JAPAN_GSI_ELEVATION_DECODER } from "@navaramap/three";

view.addSource({
  type: "raster-dem",
  url: "https://cyberjapandata.gsi.go.jp/xyz/dem_png/{z}/{x}/{y}.png",
  elevationDecoder: JAPAN_GSI_ELEVATION_DECODER(),
});

Custom decoder

You can also pass an explicit decoder object:

Property	Type	Description
`r_scaler`	`number`	Red channel scaler.
`g_scaler`	`number`	Green channel scaler.
`b_scaler`	`number`	Blue channel scaler.
`offset`	`number`	Height offset.
`max_offset`	`number`	Maximum offset value.
`min_offset`	`number`	Minimum offset value.
`boundary`	`number`	Boundary value.
`epsilon`	`number`	Epsilon (small value).

{
  elevationDecoder: {
    r_scaler: 256.0,
    g_scaler: 1.0,
    b_scaler: 1.0 / 256.0,
    offset: -32768.0,
    max_offset: 8848.0,
    min_offset: -11034.0,
    boundary: 0.01,
    epsilon: 0.001,
  },
}

About Source
Terrain Layer / Raster Layer
TerrainMaterial — terrain rendering options
HillshadeMaterial / ElevationHeatmapMaterial