Parallel planes
Fig. 1: Planes parallel to the Ground Plane (GP) or the Plane of Vision (PV) such as the plane containing the floor or the ceiling of the building, have the Horizontal Line (HL) as their common Vanishing Line (VL).
Planes parallel to the Plane of Vision (PV) but located below - such as the plane containing the platform of the building - are looked upon, planes located above PV - such as the plane containing the ceiling of the building - are looked at from below.
Fig. 2: Planes perpendicular to the Ground Plane (GP) or Plane of Vision (PV) have Vanishing Lines (VL) perpendicular to the Horizontal Line (HL). Planes parallel to each other have common Vanishing Lines (VL).
Fig. 3: Planes parallel to the Horizontal Line (HL) have Vanishing Lines (VL) parallel to the Horizontal Line (HL).
Fig. 4: Sets of parallel planes - such as the planes defined by the roofs of the buildings - neither parallel nor perpendicular to the Ground Plane (GP) or Plane of Vision (PV) converge to Vanishing Lines (VL) which are neither parallel nor perpendicular to the Horizontal Line (HL)