# Direct Roof Input

For certain roofs, it is only possible with considerable effort to generate the roof surfaces with roof projection and intersection in the required position and shape. Therefore, with these functions we have provided the ability to create a free roof surface without entering a building contour. By a free roof surface we mean a roof surface that was not created by the traditional roof projection. The roof surface is produced by intersecting a 3D plane with a polygon (polyline) that is entered in the XoY plane. We refer to this polygon in the XoY plane as the roof-contour polygon. The free surface itself can then be entered in various ways.

A free roof surface is not automatically intersected with other roof surfaces. However, dormer roof surfaces are intersected with the free roof surface.
