Linier Perspective
Diagram 3 shows a street with telegraph poles and trees disappearing into the distance. H being the horizon; V being the vanishing point where all lines meet and converge, both above and below the horizon.
Diagram 4 shows the corner of the street with a horizon line but with two vanishing points. All windows, trees, pavements and rooftops all conform to rules. In fact everything, even clouds, conform to these rules.
