# QuantizedMeshTerrainData

#### new Cesium.QuantizedMeshTerrainData(options)
engine/Source/Core/QuantizedMeshTerrainData.js 94

Terrain data for a single tile where the terrain data is represented as a quantized mesh. A quantized mesh consists of three vertex attributes, longitude, latitude, and height. All attributes are expressed as 16-bit values in the range 0 to 32767. Longitude and latitude are zero at the southwest corner of the tile and 32767 at the northeast corner. Height is zero at the minimum height in the tile and 32767 at the maximum height in the tile.

Name | Type | Description
--- | --- | ---
`options` | object | Object with the following properties:
Name | Type | Default | Description
--- | --- | --- | ---
`quantizedVertices` | Uint16Array |  | The buffer containing the quantized mesh.
`indices` | Uint16Array | Uint32Array |  | The indices specifying how the quantized vertices are linked together into triangles. Each three indices specifies one triangle.
`minimumHeight` | number |  | The minimum terrain height within the tile, in meters above the ellipsoid.
`maximumHeight` | number |  | The maximum terrain height within the tile, in meters above the ellipsoid.
`boundingSphere` | BoundingSphere |  | A sphere bounding all of the vertices in the mesh.
`orientedBoundingBox` | OrientedBoundingBox |  | optional An OrientedBoundingBox bounding all of the vertices in the mesh.
`horizonOcclusionPoint` | Cartesian3 |  | The horizon occlusion point of the mesh. If this point is below the horizon, the entire tile is assumed to be below the horizon as well. The point is expressed in ellipsoid-scaled coordinates.
`westIndices` | Array.<number> |  | The indices of the vertices on the western edge of the tile.
`southIndices` | Array.<number> |  | The indices of the vertices on the southern edge of the tile.
`eastIndices` | Array.<number> |  | The indices of the vertices on the eastern edge of the tile.
`northIndices` | Array.<number> |  | The indices of the vertices on the northern edge of the tile.
`westSkirtHeight` | number |  | The height of the skirt to add on the western edge of the tile.
`southSkirtHeight` | number |  | The height of the skirt to add on the southern edge of the tile.
`eastSkirtHeight` | number |  | The height of the skirt to add on the eastern edge of the tile.
`northSkirtHeight` | number |  | The height of the skirt to add on the northern edge of the tile.
`childTileMask` | number | `15` | optional A bit mask indicating which of this tile's four children exist. If a child's bit is set, geometry will be requested for that tile as well when it is needed. If the bit is cleared, the child tile is not requested and geometry is instead upsampled from the parent. The bit values are as follows:
Bit Position | Bit Value | Child Tile
--- | --- | ---
0 | 1 | Southwest
1 | 2 | Southeast
2 | 4 | Northwest
3 | 8 | Northeast
`createdByUpsampling` | boolean | `false` | optional True if this instance was created by upsampling another instance; otherwise, false.
`encodedNormals` | Uint8Array |  | optional The buffer containing per vertex normals, encoded using 'oct' encoding
`waterMask` | Uint8Array |  | optional The buffer containing the watermask.
`credits` | Array.<Credit> |  | optional Array of credits for this tile.

##### Example:

    const data = new Cesium.QuantizedMeshTerrainData({
        minimumHeight : -100,
        maximumHeight : 2101,
        quantizedVertices : new Uint16Array([// order is SW NW SE NE
                                             // longitude
                                             0, 0, 32767, 32767,
                                             // latitude
                                             0, 32767, 0, 32767,
                                             // heights
                                             16384, 0, 32767, 16384]),
        indices : new Uint16Array([0, 3, 1,
                                   0, 2, 3]),
        boundingSphere : new Cesium.BoundingSphere(new Cesium.Cartesian3(1.0, 2.0, 3.0), 10000),
        orientedBoundingBox : new Cesium.OrientedBoundingBox(new Cesium.Cartesian3(1.0, 2.0, 3.0), Cesium.Matrix3.fromRotationX(Cesium.Math.PI, new Cesium.Matrix3())),
        horizonOcclusionPoint : new Cesium.Cartesian3(3.0, 2.0, 1.0),
        westIndices : [0, 1],
        southIndices : [0, 1],
        eastIndices : [2, 3],
        northIndices : [1, 3],
        westSkirtHeight : 1.0,
        southSkirtHeight : 1.0,
        eastSkirtHeight : 1.0,
        northSkirtHeight : 1.0
    });

##### See:

- TerrainData
- HeightmapTerrainData
- GoogleEarthEnterpriseTerrainData

### Members

#### credits : Array.<Credit>
engine/Source/Core/QuantizedMeshTerrainData.js 216

An array of credits for this tile.

#### waterMask : Uint8Array|HTMLImageElement|HTMLCanvasElement
engine/Source/Core/QuantizedMeshTerrainData.js 228

The water mask included in this terrain data, if any. A water mask is a rectangular Uint8Array or image where a value of 255 indicates water and a value of 0 indicates land. Values in between 0 and 255 are allowed as well to smoothly blend between land and water.

### Methods

#### interpolateHeight(rectangle, longitude, latitude) → number
engine/Source/Core/QuantizedMeshTerrainData.js 571

Computes the terrain height at a specified longitude and latitude.

Name | Type | Description
--- | --- | ---
`rectangle` | Rectangle | The rectangle covered by this terrain data.
`longitude` | number | The longitude in radians.
`latitude` | number | The latitude in radians.

##### Returns:

The terrain height at the specified position. The position is clamped to the rectangle, so expect incorrect results for positions far outside the rectangle.

#### isChildAvailable(thisX, thisY, childX, childY) → boolean
engine/Source/Core/QuantizedMeshTerrainData.js 729

Determines if a given child tile is available, based on the `HeightmapTerrainData.childTileMask`. The given child tile coordinates are assumed to be one of the four children of this tile. If non-child tile coordinates are given, the availability of the southeast child tile is returned.

Name | Type | Description
--- | --- | ---
`thisX` | number | The tile X coordinate of this (the parent) tile.
`thisY` | number | The tile Y coordinate of this (the parent) tile.
`childX` | number | The tile X coordinate of the child tile to check for availability.
`childY` | number | The tile Y coordinate of the child tile to check for availability.

##### Returns:

True if the child tile is available; otherwise, false.

#### upsample(tilingScheme, thisX, thisY, thisLevel, descendantX, descendantY, descendantLevel) → Promise.<QuantizedMeshTerrainData>|undefined
engine/Source/Core/QuantizedMeshTerrainData.js 431

Upsamples this terrain data for use by a descendant tile. The resulting instance will contain a subset of the vertices in this instance, interpolated if necessary.

Name | Type | Description
--- | --- | ---
`tilingScheme` | TilingScheme | The tiling scheme of this terrain data.
`thisX` | number | The X coordinate of this tile in the tiling scheme.
`thisY` | number | The Y coordinate of this tile in the tiling scheme.
`thisLevel` | number | The level of this tile in the tiling scheme.
`descendantX` | number | The X coordinate within the tiling scheme of the descendant tile for which we are upsampling.
`descendantY` | number | The Y coordinate within the tiling scheme of the descendant tile for which we are upsampling.
`descendantLevel` | number | The level within the tiling scheme of the descendant tile for which we are upsampling.

##### Returns:

A promise for upsampled heightmap terrain data for the descendant tile, or undefined if too many asynchronous upsample operations are in progress and the request has been deferred.

#### wasCreatedByUpsampling() → boolean
engine/Source/Core/QuantizedMeshTerrainData.js 769

Gets a value indicating whether or not this terrain data was created by upsampling lower resolution terrain data. If this value is false, the data was obtained from some other source, such as by downloading it from a remote server. This method should return true for instances returned from a call to `HeightmapTerrainData#upsample`.

##### Returns:

True if this instance was created by upsampling; otherwise, false.

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