The Square in Parallel Perspective
From a given point on the base line of the picture draw a line at right angles to that base. Let P be the given point on the base line AB, and S the point of sight. We simply draw a line along the ground to the point of sight S, and this line will be at right angles to the base, as explained in Rule 5, and consequently angle APS will be equal to angle SPB, although it does not look so here. This is our first difficulty, but one that we shall soon get over.
Fig. 43.
In like manner we can draw any number of lines at right angles to the base, or we may suppose the point P to be placed at so many different positions, our only difficulty being to conceive these lines to be parallel to each other. See Rule 10.
Fig. 44.