Update App.js

public/Source/App.js

@@ -11,9 +11,9 @@
 		 animation: false,
 		 shadow: false,
 		 // // Set default basemap
-		 imageryProvider : Cesium.createOpenStreetMapImageryProvider({
-                            url : 'https://a.tile.openstreetmap.org/'
-                            }),
+		 imageryProvider : Cesium.ArcGisMapServerImageryProvider({
+    url : 'https://services.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer'
+}),
 		 baseLayerPicker: true
 		 
      });