It is convenient to follow a progression in considering how visual impressions are developed.
As conceived in geometry, a point is simply a location in space having neither dimensions nor substance- an abstract notion difficult to grasp. Two points, however, suggest a beginning and an end and lead to the idea of a connecting line. Points in a random scatter seem meaningless, but a cluster of points in a field of scatter suqqests a focus or concentration of interest.
When a point moves through space or when two points are connected, line is generated. Line, which may be straight or curved, has length but not breadth. We seem to see lines where things have edges, where one plane meets another, or where there is a change of color or surface in a plane. Straight lines can be thought of as taking several typical positions:
- Vertical Lines
These suggest stability and immobility, and, by extension, dignity and permanence. The significance of verticality comes, it seems, from the down direction of the force of gravity. This force dictates verticals, always perpendicular to all horizontals, as the basic structural support. The vertical columns of a building suggest its so and permanence.
- Horizontal Lines
These suggest rest and repose. Gravity pulls materials down to a horizontal resting point parallel to the ground in a horizontal line, and earth and sky seem to meet in a horizontal. Human experience of the horizontal reclining position in rest and sleep reinforces these perceptions. Floors and ceilings, normally horizontal, are the surfaces that give spaces their sense of reassuring normality.
- Oblique(Diagonal or Sloping) lines
These suggest movement, dynamic forces, and activity. Angled lines are always, in a sense, transitional between vertical and horizontal, the positions that gravity tolerates, and are held only through some special means of resistance to gravitational forces. A person leans forward to run, making us associate activity and movement with oblique lines.
While there can be only one horizontal and one vertical direction, oblique lines can take an infinite number of angular slopes. The combination of oblique lines in alternate directions, called a zigzag, gives a sense of restless, rapid hyperactivity. It is used to symbolize lightning, electricity, and radio waves. A sloping ceiling or wall makes a space seem active, lively, even possibly disturbing through its implication of movement.
- Curved Line
The path of a moving point that continually changes its direction gives a curved line. Curving forms occur more often in nature than rectilinear forms, leading us to perceive curvatures as more natural, freer, and me "humane" than straight-lined forms. Circles and segment circles, having a simple and clear geometric genesis, appear straightforward. More complex curvatures, such as ellipses, parabolas, and hyperbolas, are more varied and more subtle. Free curves that nave no geometric controls and combinations of curvatures in S shapes or sinuous relationships suggest increasing levels of complexity, subtlety, and softness.
- Two-dimensional Forms
A plane is a completely flat surface, created by intersecting lines. Hanes are two-dimensional, with length and width, as are plane figures that lie completely in one plane-such as the triangle, square, circle, and so on. Planes also contain irregular or free shapes that conform to no particular geometric definition. The human mind seems to be drawn toward recognition to simple geometric shapes, perhaps because, being perfect forms, they can be held in memory and reproduce ease. In a scatter of points, the eye will seek out a triangle,square, or circle or find an image with a recognizable form.
The constellations of the night sky are images suggested by the relationships of bright stars seen as points. The Big Dipper, for example, is simply an arrangement of bright points that suggests the form of a long-handled cup. Once that grouping is pointed out and named, it becomes easy to locate and recognize amid the vast number of other stars that surround it.
Design makes wide use of our attraction to perfect shapes, whose completeness and stability we find highly satisfying. Imperfect shapes, such as a square with a corner cut off or one irregular side, a circle with a dent, or a shape not fully closed, cause a sense of tension, which may be used to create a more dynamic, unusual design. However, if the "imperfection" is too strong, it leads to outright dissatisfaction and a sense of instability.
More complex forms, such as rectangles of various proportions, other quadrilaterals, polygons, and curved forms, regular and irregular, all have both practical uses and expressive visual qualities of varied sorts.
Surfaces as they occur in reality rather than in abstract geometry also have physical attributes, including:
- Texture [rough, smooth, matte, glossy, hard, soft)
- Value (light, medium, dark)
- Color (hue and saturation; "Color")
- Transparency, translucency, or opacity
A surface may be unified, as, for example, a wall painted color, or it may be subdivided by changes of material, color or pattern and may also intersect with other surfaces. Transparent and semitransparent surfaces can create complex visual including the spatial illusions resulting from reflections in polished surfaces such as glass and mirror. Surfaces have almost inevitable relationship with lines since their edges, boundaries of subdivisions, and intersections are seen as I In the fine arts, the mediums of painting, drawing, and printmaking are concerned with two-dimensional surface.
- Three-dimensional Forms
Adding depth, or volume, to a two-dimensional form create three-dimensional form. Furniture, some architectural elements (such as columns or stairs), and buildings are three-dimensional solids. Interior design is particularly concerned with hollow three-dimensional form, or space: rooms or of spaces within buildings, which are the primary element of interior design. Planes of enclosure articulate hollow space, that is, floors, walls, ceilings, which separate space inside from space outside and determine the nature of the interior space.
In most interior spaces, the planes of floors, walls, and ceilings are organized in 90-degree, or right-angled, relationships, usually called rectilinear, which are considered most stable of forms. In fact, such boxlike room forms are so common that they have come to be criticized for their monotony and lack of imagination. Small, boxlike enclosed spaces can suggest confinement and restriction or, on the other hand, privacy and intimacy. Nonrectilinear three-dimensional room forms can be generated by using non-right-angled relationships for one or more of the enclosing planes, as for example, a sloping ceiling or an angled wall, or by the use of curving planes of enclosure.
Complex hollow space can be developed by connecting several simpler forms (as in the design of Gothic and Renaissance churches, whose plans are usually based on connecting quadrilaterals and semicircles); by opening simple spaces into one another with large doorways, open wells, and similar devices; or by providing more than one level in a single space. Stairways, in addition to offering oblique planes, can be designed in complex three-dimensional terms, such as the helix of the popular spiral stair.
These are all common ways to introduce movement, openness, and variety into a space. Complex spaces can also include areas of intimacy without losing their impression of openness, as, for example, when a lowered ceiling is used over a conversation area that looks out to an open space beyond it.