can I set the 3dtiles 'CLAMP_TO_GROUND'
Unfortunately we don’t have support for this. However, you can adjust the height of your tileset like this: http://cesiumjs.org/Cesium/Apps/Sandcastle/index.html?src=3D%20Tiles%20Adjust%20Height.html&label=3D%20Tiles
Hope that helps,
because each building has different height, i hope i can make every building heigth is 0(‘CLAMP_TO_GROUND’), is this possible?