What is the best way to place subterranean gltf models with height in relation to sea level and measured in meters?
What if there is other data sources we want to place in the scene that have height in relation to terrain? Can we render these together?
You should be able to use the cartographic position and set the height. If you don’t know the absolute height, just the relative height / depth, then you can sample the terrain using the
sampleTerrainMostDetailed functions in CesiumJS, and then use an offset from that.
Also take a look at globe transparency and subterrain sandcastles in CesiumJS - Cesium Sandcastle and Cesium Sandcastle?