The height reference on entity models starts out as undefined. With this setting the height is absolute. If you set ground clamping as follows:
entity.model.heightReference = Cesium.HeightReference.CLAMP_TO_GROUND;
Then as expected the entity will sit on the ground. If you then set the height reference to NONE or undefined, then the entity still retains the CLAMP_TO_GROUND setting until you change another property on the Entity.
I tried this on billboards. Billboards work fine with setting the HeightReference to NONE, indicating this issue might be in just the 3D Model code.
Reproduction steps
Run the sandcastle example below
On the combo box select "Clamp to ground", and note the truck drops to the ground
On the combo box select "No Clamping" and note the truck stays on the ground
If you turn on "Track entity" and repeat steps 2 and 3 above the camera will move, but the 3D model will not move.
What happened?
The height reference on entity models starts out as undefined. With this setting the height is absolute. If you set ground clamping as follows:
entity.model.heightReference = Cesium.HeightReference.CLAMP_TO_GROUND;
Then as expected the entity will sit on the ground. If you then set the height reference to NONE or undefined, then the entity still retains the CLAMP_TO_GROUND setting until you change another property on the Entity.I tried this on billboards. Billboards work fine with setting the HeightReference to NONE, indicating this issue might be in just the 3D Model code.
Reproduction steps
Sandcastle example
Example
Environment
Browser: Edge version 126.0.2592.87 CesiumJS Version: 1.119 Operating System: Windows 10 22H2