Thanks for the this @omar. It doesn’t sound like the first suggestion will work as the tilesets are at angles / aren’t perfect squares so the user will be able to see a void through the surface terrain. The second option will also take too long as we could have hundreds of tilesets.
I’ve edited the ion sdk to match this closed PR as a temp fix: https://github.com/CesiumGS/cesium/pull/8203. Due to the pickpositions concerns this will only be a temp fix.
Along the same lines as your second option, we’re hoping to get updated terrain to stick on top of the world terrain where we can. For those we can’t i’m not sure, thinking out loud we may be ablt to toggle depthAgainstTerrain depending on the distance a tileset is from the camera depending on its elevation. Do you know if this issue: https://github.com/CesiumGS/cesium/issues/7879 is being worked on for an upcoming release?
Thanks for your help,
Tom