We would like to visualize under water terrain (bathymetry data); the coordinates are in both .asc and .json formats. I think the best way to visualize this underwater topography is to change the z coordinates of the terrain vertices. I am not sure how to displace the vertices of the 3d terrain in Cesium. Do I need to grab the tile for each level of detail and change the z coordinates for all of them? Please let me know if there are good tutorials or documentation on terrain displacements.