Cesium + custom terrains

cesium_terrains

    Cesium.Ion.defaultAccessToken = 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJqdGkiOiI1OGUyODEwNC03YTIzLTRjMmItOTk4Ni1iZWNkNGE1MWZhMTkiLCJpZCI6NTQzLCJpYXQiOjE1MjUyNzM4OTd9.F2r6H2XRAcnkHjkFgXAzDieW6TeIxDhTZ5hdikd-_Q8';
    var viewer = new Cesium.Viewer('cesiumContainer', {
      terrainExaggeration : 10.0
    });

    var terrainProvider = new Cesium.CesiumTerrainProvider({
      url : '/tilesets/tiles'
    });
    viewer.scene.terrainProvider = terrainProvider;

    // zoom to texel...
    viewer.camera.setView({
      destination : new Cesium.Cartesian3.fromDegrees(4.7128563,53.051284, 500),
      orientation: {
        heading : Cesium.Math.toRadians(30),
        pitch : Cesium.Math.toRadians(-20),
        roll : 0.0
      }
    });