The invention notably relates to a method for performing a 3D structural restoration of a geological setting with a computer system, including unfolding one or more geological surfaces of the geological setting. The unfolding comprises for each respective geological surface providing a 3D triangulated surface representing the respective geological surface, and determining a conformal flattening that transforms the 3D triangulated surface into a 2D triangulated surface. The conformal flattening is an iso-topographic mapping which substantially preserves angles. This provides an improved solution of 3D structural restoration of a geological setting.