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Transcript of Depth/Volume [Zettl]
We are constantly working through the process of projecting a 3D environment onto a 2D surface. We're willing to accept a projection "as a true representation of all three dimensions: height, width, and depth."
Z-Axis — "The axis in the coordinating system that defines depth. Also the imaginary line that extends from the camera lens to the horizon."
If we look at a singular scene as a 3D model, we'll be attempting to locate figures or content not only on the Z-axis, but also on the X and Y axis.
Graphic Depth Factors — Features that "create the illusion of three-dimensional space on a two-dimensional surface (without the use of motion)."
Height In Plane
Light and Shadow
Overlapping Plane — "The most direct of the graphic depth factors: when you see one object partially covering another, you know that the one doing the covering must be in front of the one that is covered. Technically called occlusion."
Relative Size — If you know how big an object is, you can guess its position on the z-axis.
"If you know that two objects are similar or identical in size, you perceive the smaller screen image as being farther away and the larger screen image as being closer."
In the next examples, how do they use these previously mentioned concepts?
Height in Plane — When we're shooting parallel to the ground (a horizontal plane), "we will perceive an object as being more and more distant the higher it moves up in the picture field until it has reached the horizon line."
Not always reliable, given the mobility of the camera.
Vanishing Point — The point at which all parallel lines converge and discontinue (vanish) is aptly called the vanishing point. The vanishing point always lies at eye (or camera) level on the horizon line.
If you have a single vanishing point, as in the example below, you've established something called a "one point perspective."
"This type of perspective is typically used for images of roads, railway tracks, hallways, or buildings viewed so that the front is directly facing the viewer."
Linear Perspective — "Among the more powerful and convincing graphic depth factors: horizontal parallel lines converge toward the distance at the vanishing point, which lies on the eye-level horizon line. Vertical lines (such as windows) crowd progressively toward the vanishing point."
In other words, all objects look progressively smaller the farther away they are, vertical and horizontal lines becoming more crowded as they move away from the observer
Eye Level — "The plane parallel to the ground, emanating from the eye of the observer. Eye level and the horizon line lie on the same plane regardless of how high the observer is from the ground."
Horizon Line — "The line formed by the actual horizon or an imaginary line parallel to the ground at eye level."
To find these lines, you simply "stand straight and look straight forward or point the camera parallel to the ground."
Crowding Effect — When depth is generated because items get closer and closer as they move higher up in a picture plane. Can serve as an important depth cue.
Forced Perspective — An exaggerated linear perspective, making us perceive parallel lines converging more drastically than in normal vision. Creating the crowding effect on purpose.
We see objects that are close to us somewhat more sharply than those farther away, a phenomenon known as aerial perspective.
"Colors also lose their density and become less saturated the farther away they are from the observer (camera). Outdoors, distant colors take on a slightly blue tint."
Leonardo da Vinci first used the term aerial perspective in his Treatise on Painting, in which he wrote: “Colours become weaker in proportion to their distance from the person who is looking at them.”
Often used in painting, as those objects distant in the landscape will take on a blue hue to copy what happens in the natural world. As objects are more distant, they lose their contrast to the background and start to take on background color (usually blue).
If creating scenery...