No fence, wall, sign, hedge, screen or any planting shall be erected or maintained to obstruct vision between a height of three feet and eight feet within the triangular area formed by the intersection of the street right-of-way lines and a line connecting two points which are located on those intersecting right-of-way lines 15 feet from the point of intersection of the right-of-way lines. The three foot and eight foot height limit shall be measured from the lowest elevation of the segment of the intersecting roads centerline which lays between the point of the intersection of the other centerline and the extension of the line drawn through the points 20 feet from the intersection of the right-of-way lines.