# Cesium3DTilesTerrainProvider

#### new Cesium.Cesium3DTilesTerrainProvider(options)
engine/Source/Core/Cesium3DTilesTerrainProvider.js 68

To construct a Cesium3DTilesTerrainProvider, call `Cesium3DTilesTerrainProvider.fromIonAssetId` or `Cesium3DTilesTerrainProvider.fromUrl`. Do not call the constructor directly.
A `TerrainProvider` that accesses terrain data in a 3D Tiles format.

Name | Type | Description
--- | --- | ---
`options` | Cesium3DTilesTerrainProvider.ConstructorOptions | optional An object describing initialization options

##### Experimental

This feature is not final and is subject to change without Cesium's standard deprecation policy.

##### See:

- TerrainProvider
- Cesium3DTilesTerrainProvider.fromUrl
- Cesium3DTilesTerrainProvider.fromIonAssetId // Create GTOPO30 with vertex normals try { const viewer = new Cesium.Viewer("cesiumContainer", { terrainProvider: await Cesium.Cesium3DTilesTerrainProvider.fromIonAssetId(2732686, { requestVertexNormals: true }) }); } catch (error) { console.log(error); }

### Members

#### availability : TileAvailability|undefined
engine/Source/Core/Cesium3DTilesTerrainProvider.js 752

Gets an object that can be used to determine availability of terrain from this provider, such as at points and in rectangles.

#### credit : Credit
engine/Source/Core/Cesium3DTilesTerrainProvider.js 705

Gets the credit to display when this terrain provider is active. Typically this is used to credit the source of the terrain.

#### errorEvent : Event
engine/Source/Core/Cesium3DTilesTerrainProvider.js 693

Gets an event that is raised when the terrain provider encounters an asynchronous error. By subscribing to the event, you will be notified of the error and can potentially recover from it. Event listeners are passed an instance of `TileProviderError`.

#### hasVertexNormals : boolean
engine/Source/Core/Cesium3DTilesTerrainProvider.js 740

Gets a value indicating whether or not the requested tiles include vertex normals.

#### hasWaterMask : boolean
engine/Source/Core/Cesium3DTilesTerrainProvider.js 729

Gets a value indicating whether or not the provider includes a water mask. The water mask indicates which areas of the globe are water rather than land, so they can be rendered as a reflective surface with animated waves.

#### tilingScheme : TilingScheme
engine/Source/Core/Cesium3DTilesTerrainProvider.js 716

Gets the tiling scheme used by the provider.

### Methods

#### static Cesium.Cesium3DTilesTerrainProvider.fromIonAssetId(assetId, options) → Promise.<CesiumTerrainProvider>
engine/Source/Core/Cesium3DTilesTerrainProvider.js 206

Creates a `TerrainProvider` from a Cesium ion asset ID that accesses terrain data in a Cesium 3D Tiles format

Name | Type | Description
--- | --- | ---
`assetId` | number | The Cesium ion asset id.
`options` | CesiumTerrainProvider.ConstructorOptions | optional An object describing initialization options.

##### Returns:

##### Throws:

- RuntimeError : layer.json does not specify a format
- RuntimeError : layer.json specifies an unknown format
- RuntimeError : layer.json specifies an unsupported quantized-mesh version
- RuntimeError : layer.json does not specify a tiles property, or specifies an empty array
- RuntimeError : layer.json does not specify any tile URL templates

##### Example:

    // Create GTOPO30 with vertex normals
    try {
      const viewer = new Cesium.Viewer("cesiumContainer", {
        terrainProvider: await Cesium.Cesium3DTilesTerrainProvider.fromIonAssetId(2732686, {
            requestVertexNormals: true
        })
      });
    } catch (error) {
      console.log(error);
    }

#### static Cesium.Cesium3DTilesTerrainProvider.fromUrl(url, options) → Promise.<Cesium3DTilesTerrainProvider>
engine/Source/Core/Cesium3DTilesTerrainProvider.js 138

Creates a `TerrainProvider` that accesses terrain data in a Cesium 3D Tiles format.

Name | Type | Description
--- | --- | ---
`url` | Resource | string | Promise.<Resource> | Promise.<string> | The URL of the Cesium terrain server.
`options` | Cesium3DTilesTerrainProvider.ConstructorOptions | optional An object describing initialization options.

##### Returns:

A promise that resolves to the terrain provider.

##### Example:

    // Create terrain with normals.
    try {
      const viewer = new Cesium.Viewer("cesiumContainer", {
        terrainProvider: await Cesium.Cesium3DTilesTerrainProvider.fromUrl(
          Cesium.IonResource.fromAssetId(3956), {
            requestVertexNormals: true
        })
      });
    } catch (error) {
      console.log(error);
    }

#### getLevelMaximumGeometricError(level) → number
engine/Source/Core/Cesium3DTilesTerrainProvider.js 673

Get the maximum geometric error allowed in a tile at a given level.

Name | Type | Description
--- | --- | ---
`level` | number | The tile level for which to get the maximum geometric error.

##### Returns:

The maximum geometric error.

#### getTileDataAvailable(x, y, level) → boolean|undefined
engine/Source/Core/Cesium3DTilesTerrainProvider.js 410

Determines whether data for a tile is available to be loaded.

Name | Type | Description
--- | --- | ---
`x` | number | The X coordinate of the tile for which to request geometry.
`y` | number | The Y coordinate of the tile for which to request geometry.
`level` | number | The level of the tile for which to request geometry.

##### Returns:

Undefined if not supported or availability is unknown, otherwise true or false.

#### loadTileDataAvailability(_x, _y, _level) → Promise.<void>|undefined
engine/Source/Core/Cesium3DTilesTerrainProvider.js 659

Make sure we load availability data for a tile

Name | Type | Description
--- | --- | ---
`_x` | number | The X coordinate of the tile for which to request geometry.
`_y` | number | The Y coordinate of the tile for which to request geometry.
`_level` | number | The level of the tile for which to request geometry.

##### Returns:

Undefined if nothing need to be loaded or a Promise that resolves when all required tiles are loaded

#### requestTileGeometry(x, y, level, request) → Promise.<Cesium3DTilesTerrainData>|undefined
engine/Source/Core/Cesium3DTilesTerrainProvider.js 234

Requests the geometry for a given tile. This function should not be called before `Cesium3DTilesTerrainProvider#ready` returns true. The result must include terrain data and may optionally include a water mask and an indication of which child tiles are available.

Name | Type | Description
--- | --- | ---
`x` | number | The X coordinate of the tile for which to request geometry.
`y` | number | The Y coordinate of the tile for which to request geometry.
`level` | number | The level of the tile for which to request geometry.
`request` | Request | optional The request object. Intended for internal use only.

##### Returns:

A promise for the requested geometry. If this method returns undefined instead of a promise, it is an indication that too many requests are already pending and the request will be retried later.

### Type Definitions

#### Cesium.Cesium3DTilesTerrainProvider.ConstructorOptions
engine/Source/Core/Cesium3DTilesTerrainProvider.js 29

Initialization options for the Cesium3DTilesTerrainProvider constructor

##### Properties:

Name | Type | Attributes | Default | Description
--- | --- | --- | --- | ---
`requestVertexNormals` | boolean | <optional> | false | Flag that indicates if the client should request additional lighting information from the server, in the form of per vertex normals if available.
`requestWaterMask` | boolean | <optional> | false | Flag that indicates if the client should request per tile water masks from the server, if available.
`ellipsoid` | Ellipsoid | <optional> | Ellipsoid.default | The ellipsoid. If not specified, the WGS84 ellipsoid is used.
`credit` | Credit | string | <optional> |  | A credit for the data source, which is displayed on the canvas.

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