const getHeight = (lng: any, lat: any) => {

  var positions = Cesium.Cartographic.fromDegrees(lng, lat);

  let promise = Cesium.sampleTerrainMostDetailed(viewer.terrainProvider, [

    positions,

  ]);

  promise.then((updatedPositions) => {

    console.log("zhang", lng, lat, updatedPositions[0].height);

  });

};