pickPosition() ignore 3D model

3D Model (glb) is added on 3D Tileset.
I want to move this 3D Model by mouse drag and drop.
While dragging, I want to get the position on the 3D Tiles, but pickPosition() hits the 3D Model and returns the position on the 3D Model.
How can I ignore the 3D Model and get the position on the 3D Tiles while dragging?