Check if cartographic is defined before getting height
Check if cartographic is defined before getting height

YonatanKra/cesium,hodbauer/cesium,soceur/cesium,likangning93/cesium,progsung/cesium,YonatanKra/cesium,likangning93/cesium,AnalyticalGraphicsInc/cesium,hodbauer/cesium,hodbauer/cesium,AnalyticalGraphicsInc/cesium,YonatanKra/cesium,geoscan/cesium,YonatanKra/cesium,jasonbeverage/cesium,kaktus40/cesium,CesiumGS/cesium,soceur/cesium,CesiumGS/cesium,soceur/cesium,CesiumGS/cesium,likangning93/cesium,josh-bernstein/cesium,CesiumGS/cesium,likangning93/cesium,kaktus40/cesium,progsung/cesium,josh-bernstein/cesium,likangning93/cesium,CesiumGS/cesium,jasonbeverage/cesium,geoscan/cesium