I placed the ceiling elements by surface whith help of FamilyInstanceByPoint. But I want it starting on the one flat ceiling (surface). How to create this?
You need to look for the intersection and to feed that as the Z value
@goggy91 Ideally you’d try to have them placed properly in the first instance.
However, if you need to move them later, you’ll need to calculate the distance each instance needs to be moved.
Then you can apply that value to the relevant parameter of the family instance.