I had made add a line layer using cesium. In which I had added a terrain effect using the standard cesium terrain provider. I am having problem as mentioned here
Cesium does not currently have support for polylines on terrain. It is a surprisingly difficult problem to solve and we are currently researching what the best approach would be to add this feature. We hope to have this available within the next year.
Keep an eye on the Vector Data on Terrain GitHub issue for updates: https://github.com/AnalyticalGraphicsInc/cesium/issues/2172