A method to determine at least one formation property of a subterranean formation includes providing a downhole electromagnetic logging tool having at least one transmitter array and one receiver array to acquire measurements in the formation. The method further includes performing a first inversion in response to the measurements, assuming dip or dip azimuth is constant in an inversion zone within the formation to obtain an inverted formation model. The method includes determining an n-th order partial derivative matrix of at least one of dip or dip azimuth, wherein n is greater than or equal to 1. The method includes performing a second inversion using the determined n-th order partial derivative matrix, wherein at least one of dip and dip azimuth are allowed to vary in the inversion zone, to obtain an updated formation model. The method includes determining the formation property using the updated formation model.