Imagine the line of sight as a 10 foot long piece of string. It starts at the station point, moves horizontally towards the picture plane and ends at the center of vision. Next, imagine cutting the string at the station point and letting it fall. The string, while still connected to the picture plane, would swing down and rest on the picture plane. It’s important to realize that the string is still 10 feet long. By transferring this dimension onto the picture plane, we can now represent a specific distance in our drawings.
This is what ‘seeing’ looks like when working in perspective.
Center of Vision
Horizon Line
Line of Sight (dropped onto the picture plane)
Ground Plane
Station Point
The horizon line represents the viewer’s eye level, the station point helps us measure distance to the picture plane, and, when working in either one or two-point perspective, we assume the viewer is looking straight ahead. Taken together, these three measurements (height, viewing angle, and distance) effectively place our viewer at the scene. Next, we’ll talk about what happens when we give the viewer something to look at.