fromWorldTerrain

// Create Cesium World Terrain with default settings
const viewer = new Viewer("cesiumContainer", {
  terrain: fromWorldTerrain()
});

// Create Cesium World Terrain with water and normals.
const viewer1 = new Viewer("cesiumContainer", {
  terrain: fromWorldTerrain({
     requestWaterMask: true,
     requestVertexNormals: true
   });
});

// Handle loading events
const terrain = Terrain.fromWorldTerrain();

scene.setTerrain(terrain);

terrain.readyEvent.addEventListener(provider => {
  scene.globe.enableLighting = true;

  terrain.provider.errorEvent.addEventListener(error => {
    alert(`Encountered an error while loading terrain tiles! ${error}`);
  });
});

terrain.errorEvent.addEventListener(error => {
  alert(`Encountered an error while creating terrain! ${error}`);
});