:*In LoD2 a solid contains external references (Xlinks) to the real bounding geometry. '''In real nonexistent surfaces''' are modeled as closure surfaces and assigned directly to the building part ('''Figure C'''). | :*In LoD2 a solid contains external references (Xlinks) to the real bounding geometry. '''In real nonexistent surfaces''' are modeled as closure surfaces and assigned directly to the building part ('''Figure C'''). |