On a corner lot in a residential district, nothing shall be erected, placed, planted, or allowed to grow in such a manner as materially to impede vision between a height of two and one-half (2½) and ten (10) feet above the centerline grades of the intersecting streets in the area bounded by the street lines of such corner lots and a line joining points along said street lines twenty-five (25) feet from the point of intersection of right-of-way lines.