I believe that I already know the answer to this based on the looking around I've done but I currently have a need to have a time dynamic cylinder within Cesium. Since it's time dynamic, naturally I reached for CZML but I don't see a way to clamp a cylinder to the ground. I see the option in the czml docs for other entity types but not cylinders.
Is this option simply not supported? Only asking because I don't know how up to date the CZML documentation is since it seems to be kinda old.
My go to is always the Entity documentation instead, so you can see it does support a height reference for a cylinder:
https://cesiumjs.org/Cesium/Build/Documentation/CylinderGraphics.html?classFilter=CylinderGr
CZML should reflect all properties an Entity can have. If it doesn’t (like what might be in this case) we should open a bug report (or a code contribution!)
Also, you can still do time dynamic stuff without CZML, like in this example: https://cesiumjs.org/Cesium/Build/Apps/Sandcastle/?src=Time%20Dynamic%20Wheels.html