All parallel retiring lines have the same vanishing point as each other.
All horizontal lines which are parallel with the picture plane are drawn parallel with each other, and with the line of sight.
All horizontal retiring lines forming right angles with the picture plane, or with our position, have the point of sight for their vanishing point.
We have here introduced a new term, the picture plane. The best way to understand this is to imagine you are looking at everything through a pane of glass. In this case the glass would be the picture plane, and if we could stand steadily enough in one place and trace upon the window pane the lines of the streets and houses, we should find the lines upon the pane following the rules we have given.
Many of the rules of perspective are to be seen in the sketch of Rigg’s Farm, Wensleydale, Yorkshire, Fig. 4. The receding lines of the road, the grass edges, and the walls; the front of the farmhouse is so much foreshortened that it is possible to see only a very small part of it, though the building is really a long one.
Sketch at Norton.
We have given also a sketch by Rembrandt, and a pen and ink landscape drawing made at Norton in North Derbyshire by Charles Ashmore.
Saskia Van Ulenburgh, Rembrandt’s Wife.
From a drawing by Rembrandt in the Berlin Museum.