HeightmapTerrainData

new HeightmapTerrainData

Terrain data for a single tile where the terrain data is represented as a heightmap. A heightmap is a rectangular array of heights in row-major order from south to north and west to east.

Parameters:

Name Type Argument Default Description

description.buffer TypedArray The buffer containing height data.

description.width Number The width (longitude direction) of the heightmap, in samples.

description.height Number The height (latitude direction) of the heightmap, in samples.

description.childTileMask

Number

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

description.structure

Object

An object describing the structure of the height data.

Properties

Name	Type	Argument	Default	Description
`heightScale`	Number	<optional>	1.0	The factor by which to multiply height samples in order to obtain the height above the heightOffset, in meters. The heightOffset is added to the resulting height after multiplying by the scale.
`heightOffset`	Number	<optional>	0.0	The offset to add to the scaled height to obtain the final height in meters. The offset is added after the height sample is multiplied by the heightScale.
`elementsPerHeight`	Number	<optional>	1	The number of elements in the buffer that make up a single height sample. This is usually 1, indicating that each element is a separate height sample. If it is greater than 1, that number of elements together form the height sample, which is computed according to the structure.elementMultiplier and structure.isBigEndian properties.
`stride`	Number	<optional>	1	The number of elements to skip to get from the first element of one height to the first element of the next height.
`elementMultiplier`	Number	<optional>	256.0	The multiplier used to compute the height value when the stride property is greater than 1. For example, if the stride is 4 and the strideMultiplier is 256, the height is computed as follows: `height = buffer[index] + buffer[index + 1] * 256 + buffer[index + 2] * 256 * 256 + buffer[index + 3] * 256 * 256 * 256` This is assuming that the isBigEndian property is false. If it is true, the order of the elements is reversed.
`isBigEndian`	Boolean	<optional>	false	Indicates endianness of the elements in the buffer when the stride property is greater than 1. If this property is false, the first element is the low-order element. If it is true, the first element is the high-order element.

description.createdByUpsampling Boolean <optional> false True if this instance was created by upsampling another instance; otherwise, false.

Example

var buffer = ...
var heightBuffer = new Uint16Array(buffer, 0, that._heightmapWidth * that._heightmapWidth);
var childTileMask = new Uint8Array(buffer, heightBuffer.byteLength, 1)[0];
var waterMask = new Uint8Array(buffer, heightBuffer.byteLength + 1, buffer.byteLength - heightBuffer.byteLength - 1);
var structure = Cesium.HeightmapTessellator.DEFAULT_STRUCTURE;
var terrainData = new Cesium.HeightmapTerrainData({
  buffer : heightBuffer,
  width : 65,
  height : 65,
  childTileMask : childTileMask,
  structure : structure,
  waterMask : waterMask
});

See:

Source:

/Source/Scene/HeightmapTerrainData.js

Methods

createMesh

Creates a TerrainMesh from this terrain data.

Parameters:

Name	Type	Description
`tilingScheme`	TilingScheme	The tiling scheme to which this tile belongs.
`x`	Number	The X coordinate of the tile for which to create the terrain data.
`y`	Number	The Y coordinate of the tile for which to create the terrain data.
`level`	Number	The level of the tile for which to create the terrain data.

Returns:

Promise | TerrainMesh A promise for the terrain mesh, or undefined if too many asynchronous mesh creations are already in progress and the operation should be retried later.

getWaterMask

Gets 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.

Returns:

Uint8Array | Image | Canvas The water mask, or undefined if no water mask is associated with this terrain data.

interpolateHeight

Computes the terrain height at a specified longitude and latitude.

Parameters:

Name	Type	Description
`extent`	Extent	The extent covered by this terrain data.
`longitude`	Number	The longitude in radians.
`latitude`	Number	The latitude in radians.

Returns:

Number The terrain height at the specified position. If the position is outside the extent, this method will extrapolate the height, which is likely to be wildly incorrect for positions far outside the extent.

isChildAvailable

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.

Parameters:

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:

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

upsample

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

Parameters:

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:

Promise | HeightmapTerrainData 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

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:

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