sampleTerrain(terrainProvider, level, positions)Promise.<Array.<Cartographic>>

Initiates a terrain height query for an array of Cartographic positions by requesting tiles from a terrain provider, sampling, and interpolating. The interpolation matches the triangles used to render the terrain at the specified level. The query happens asynchronously, so this function returns a promise that is resolved when the query completes. Each point height is modified in place. If a height can not be determined because no terrain data is available for the specified level at that location, or another error occurs, the height is set to undefined. As is typical of the Cartographic type, the supplied height is a height above the reference ellipsoid (such as Ellipsoid.WGS84) rather than an altitude above mean sea level. In other words, it will not necessarily be 0.0 if sampled in the ocean. This function needs the terrain level of detail as input, if you need to get the altitude of the terrain as precisely as possible (i.e. with maximum level of detail) use sampleTerrainMostDetailed.
Name Type Description
terrainProvider TerrainProvider The terrain provider from which to query heights.
level Number The terrain level-of-detail from which to query terrain heights.
positions Array.<Cartographic> The positions to update with terrain heights.
A promise that resolves to the provided list of positions when terrain the query has completed.
// Query the terrain height of two Cartographic positions
var terrainProvider = Cesium.createWorldTerrain();
var positions = [
    Cesium.Cartographic.fromDegrees(86.925145, 27.988257),
    Cesium.Cartographic.fromDegrees(87.0, 28.0)
var promise = Cesium.sampleTerrain(terrainProvider, 11, positions);
Cesium.when(promise, function(updatedPositions) {
    // positions[0].height and positions[1].height have been updated.
    // updatedPositions is just a reference to positions.