But Filippo noticed something even more strange. Because the vanishing point is always at your eye level, if you sit, the vanshing point lowers, and all the edges move as you do to your new vanishing point. (Animate illustration and have Filippo sit.) Look what happens when he lies on the ground! His point of view has changed, and so has his perspective. That's where we get the word; Perspective. It's unique and different for everyone!
Everything we can add to the picture has to agree with perspective. (Revert image to Filippo's standing position) If we add a neat row of trees to the side of the road they will follow the same rules. They will appear to get smaller as they go back along the road, even appearing to get closer and closer together.
If Filippo had a friend with him, and the friend walked down the street, as the friend walked, he would appear to become smaller and smaller. We could draw lines from his friend's feet and head going to the vanishing point, and know exactly how tall he would be within the image based on Filippo's perspective. (A strobe-like animation would help here)
Objects in the foreground, or the front, appear to get smaller as they go further away and closer to Filippo's vanishing point. If we add a building to the image, we can see that its windows, doors, and roof would follow the same rules.
Since Filippo's time, artists throughout history, even today, use his discovery to create their own works of art and make them look three dimensional.
Let’s look at Vincent van Gogh’s painting of his bedroom. Since he painted it, we might be able to find out his eye level. Before we do, make a guess. Was he sitting or standing when he painted this image? We know he was 5 ft, 7 inches tall, or a total of 67 inches.
Using the bed frame and connecting the parts that recede we can find an approximate vanishing point. See how the lines come together to one place. This was his vanishing point. His eyes were at that height when he painted this. (Could include animation showing the scene as drawn from close to the floor, and again close to the ceiling, illustrating how forms change with perspective)
We need to use something for a reference for his height. We’ll use the chair. We know most chairs have a seat height of about 17 inches. (In the 1800s: http://www.aaawt.com/html/gallery9.html ) When you take one leg of the chair as a reference, you’ll see it takes about 3 of them to go to the horizon line. 3 x 17 = 51. When you subtract 51 from 67, there are 16 inches different. Even when you account for the top of his head from his eye level it becomes clear he was probably not standing, but sitting, and likely on a stool. (Transition, animate through van Gogh's window to the balcony scene)
When you look to the bottom of the painting, their building is blocked by trees. We can’t see the base of their building, but we can see the building across the street. By finding where receding lines converge, we can find the height of the artist’s eyes. When we draw a horizontal, that’s the eye level of the artist. We can count the number of floors high that line is across the street, 4, and know the balcony’s floor will be at that same level, the fourth floor. When we look up, we can see where the building ends, so we can deduce the total floor height of the building they were in is four.
The building in the painting is not a real place, but if it were, how tall might it be? We need a point of reference to measure the elements within the image. If we look on the left of the main arch, there is a man standing against it and standing tall. He looks to be average height, not too tall and not too short. The average height of a man in the renaissance was about five and one half feet. Though we can’t see his feet we can use the floor grid to find where his feet would be. Based on this we can see the wall he is standing at is about 3.3 times his height, or about 18 feet tall. The arch is a barrel vault based on half a circle. It’s about half height of the wall. So another 9 feet tall. So the wall and arch together are about 24 feet tall. Based on other buildings with domes, like the Vatican of Rome, and others from about that time, we know a dome doubles a building’s height. We can make a guess that the entire building is about 48 to 50 feet tall on the inside.
What else can you learn by being a Perspective Detective? Explore more with your art teacher.