“Advertising surface (facing)” means the entire surface plane on which any type of letter, figure, emblem, trademark, picture, or other advertising material is placed, or may be placed. In the case of the sphere of any type, only one-half thereof shall be considered the “advertising surface (facing)” unless the sphere may be observed on all sides by the public, in which event the entire surface area of the sphere shall be considered the “advertising surface (facing).” In the case of freestanding letters, numerals, pictures, or other advertising material, the “advertising surface (facing)” shall be computed by enclosing the entire area constituting the advertising message within a parallelogram or triangle. (Ord. 89-3 (part), 1989)