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Learning Art > Drawing > Aspects of Drawing > Perspective

Perspective

Perspective works by representing the light that passes from a scene, through an imaginary rectangle (the drawing or sketch), to the viewer's eye. It is similar to a viewer looking through a window and painting what is seen directly onto the windowpane. If viewed from the same spot as the windowpane was drawn, the drawn image would be identical to what was seen through the unpainted window.

Each drawn object in the scene is a flat, scaled down version of the object on the other side of the window. Because each portion of the painted object lies on the straight line from the viewer's eye to the equivalent portion of the real object it represents, the viewer cannot perceive (sans depth perception) any difference between the drawn scene on the windowpane and the view of the real scene.

If the viewer is standing in a different spot, the illusion should be ruined, but unless the viewer chooses an extreme angle, like looking at it from the bottom corner of the window, the perspective normally looks more or less correct.

Simple perspective

Of the many types of perspective drawings, the most common categorizations of artificial perspective are one-, two- and three-point. The names of these categories refer to the number of vanishing points in the perspective drawing. Strictly speaking, these types can only exist for scenes being represented that are rectilinear (composed entirely of straight lines which intersect only at 90 degrees to each other).

One-Point Perspective
One vanishing point is typically used for roads, railroad tracks, or buildings viewed so that the front is directly facing the viewer. Any objects that are made up of lines either directly parallel with the viewer's line of sight (like railroad tracks) or directly perpendicular (the railroad slats) can be represented with one-point perspective.

One Point Perspective

One-point perspective exists when the painting plate (also known as the picture plane) is parallel to two axes of a rectilinear (or Cartesian) scene --- a scene which is composed entirely of linear elements that intersect only at right angles. If one axis is parallel with the picture plane, then all elements are either parallel to the painting plate (either horizontally or vertically) or perpendicular to it. All elements that are parallel to the painting plate are drawn as parallel lines. All elements that are perpendicular to the painting plate converge at a single point (a vanishing point) on the horizon.

Two-Point Perspective
Two-point perspective can be used to draw the same objects as one-point perspective, rotated: looking at the corner of a house, or looking at two forked roads shrink into the distance, for example. One point represents one set of parallel lines, the other point represents the other. Looking at a house from the corner, one wall would recede towards one vanishing point, the other wall would recede towards the opposide vanishing point.

Two Point Perspective

Two-point perspective exists when the painting plate is parallel to a Cartesian scene in one axis (usually the z-axis) but not to the other two axes. If the scene being viewed consists solely of a cylinder sitting on a horizontal plane, no difference exists in the image of the cylinder between a one-point and two-point perspective.

Three-Point Perspective
Three-point perspective is usually used for buildings seen from above. In addition to the two vanishing points from before, one for each wall, there is now one for how those walls recede into the ground. Looking up at a tall building is another common example of the third vanishing point.

Three Point Perspective

Three-point perspective exists when the perspective is a view of a Cartesian scene where the picture plane is not parallel to any of the scene's three axes. Each of the three vanishing points corresponds with one of the three axes of the scene.

Zero-point perspective
Due to the fact that vanishing points exist only when parallel lines are present in the scene, a perspective without any vanishing points ("zero-point" perspective) occurs if the viewer is observing a nonlinear scene.

The most common example of a nonlinear scene is a natural scene (ie, a mountain range) which frequently does not contain any parallel lines. Other examples include: a random (ie, not aligned in a three-dimensional Cartesian coordinate system) arrangement of spherical objects, a scene composed entirely of three-dimensionally curvilinear strings, or a scene consisting of lines where no two are parallel to each other.

Orthographic projections also do not have vanishing points, but they are not perspective constructions and are thus not equivalent to a "zero-point" perspective. Note that a perspective without vanishing points can still create a sense of "depth," as is clearly apparent in a photograph of a mountain range (for example, more distant mountains have smaller scale features).

Linear perspective
Linear perspective is a method of portraying objects on a flat surface so that the dimensions shrink with distance. The parallel, straight edges of any object, whether a building or a table, will follow lines that eventually converge at infinity. Typically this point of convergence will be along the horizon, as buildings are built level with the flat surface. When multiple structures are aligned with each other, such as buildings along a street, the horizontal tops and bottoms of the structures will all typically converge at a vanishing point.

Depth can also be portrayed by several techniques in addition to the perspective approach above. Objects of similar size should appear ever smaller the further they are from the viewer. Thus the back wheel of a cart will appear slightly smaller than the front wheel. Depth can be portrayed through the use of texture.

As the texture of an object gets further away it becomes more compressed and busy, taking on an entirely different character than if it was close. Depth can also be portrayed by reducing the amount of contrast of more distant objects, and also by making the colors more pale. This will reproduce the effect of atmospheric haze, and cause the eye to focus primarily on objects drawn in the foreground

Excerpts from Wikipedia, The Free Encyclopedia

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Perspective

Zero-point perspective Due to the fact that vanishing points exist only when parallel lines are present in the scene, a perspective without any vanishing points ("zero-point" perspective) occurs if the viewer is observing a nonlinear scene.

More Articles on Drawing

Zero-point perspective
Due to the fact that vanishing points exist only when parallel lines are present in the scene, a perspective without any vanishing points ("zero-point" perspective) occurs if the viewer is observing a nonlinear scene.