HOW TO DRAW A SPIRAL STAIRCASE IN PARALLEL PERSPECTIVE
(continued 4)

Figure nº 27 shows the construction of a ground plan in perspective in relation to the staircase steps. Then, the walls of a box with the exact dimensions of the staircase were constructed. Note that the height of the box exceeded the measurements of our visual field. This is not relevant when it refers to height. But a larger width can not exceed the depth point. All ground plans can be worked similarly to this. Not only the staircases, but all objects displaying the most sophisticated forms. The construction in millimeters to scale allows us to obtain photographic images of the drawings made. See staircase constructed at left.

You can see in Figure nº 27 that the edges of the first plane are changed into measurement lines. These measurements are transferred to the back edges by the vanishing point on the horizon line. The measurements of the front edge will be transferred to the median line (line on the center of the drawing) by the depth point located on the horizon line.