Concentric

Radiation - The Concentric Structure
In a concentric structure, instead of radiating from the center as in a centrifugal structure, structural lines surround the center in regular layers.

a) The Basic Concentric Structure. This consists of layers of equally spaced circles enclosing the center of the design which is also the common center of all the circles.

b) Straightening, Curving, or Bending of Structural Lines. The concentric structural lines as in (a) can be straightened, curved, or bent regularly, as desired. In fact, any single shape can be made into concentric layers.

c) Shifting of Centers. Instead of having a common center, the circles can shift their centers along the track of a line, which may be straight, curved, bent, and possibly forming a circle, triangle, square, or any desired shape. Usually swirling movements result.

d) The Spiral. A geometrically perfect spiral is very difficult to construct. However, a less perfect but still regular spiral can be obtained by dissecting the basic concentric structure and putting the sectors back again. Shifting of centers and adjusting of the radii of the circles can also produce a spiral. A spiral pattern generates strong centrifugal force, so it is halfway between a centrifugal and a concentric structure.

e) Multiple Centers. By taking a section or a sector of a concentric structure and repeating it, sometimes with necessary adjustments, a concentric structure with multiple centers can be constructed.

f) Distorted and/or Hidden Centers. This can be created in the same way as described in (e), but instead of resulting in multiple centers, the design may contain a distorted center, or several hidden centers.

g) Gradual Rotation of Concentric Layers. If the concentric layers are not perfect circles but squares, polygons, or irregular shapes, they can be gradually rotated.

h) Concentric Layers with Centrifugal Radiations. Centrifugal radiations can be constructed within each concentric layer.

i) Reorganized Concentric Layers. The concentric layers can be reorganized so that some of the structural lines can be bent and linked with other structural lines, resulting in interwoven patterns with one or more centers.

[Wong, Wucius. Principals of Two-Dimensional Design. New York: Van Nostrand Reinhold Company, 1972.]

Gradation- Patterns of Gradation
In a gradation design, two factors are of importance in pattern construction: the range of gradation, and the direction of movement.

The range of gradation is marked by a starting situation and a terminating situation. In some cases, where the path of gradation is not straightforward but roundabout, intermediate situations should be taken into account. The number of steps between the starting and the terminating situations determines both the speed and the breadth of the range of gradation.

The direction of movement refers to the orientations of the starting and the terminating situations and their interrelationship. The unit forms of the starting situation can all be lined up in a row and proceed lengthwise, breadthwise, or both, with regular steps towards the terminating situation. Diagonal or other ways of progression are also possible.

Some typical movement patterns in gradation are:

Parallel Movement. This is the simplest. Unit forms are transformed gradually in parallel steps. In parallel movement, the climax is usually a straight line.

Concentric Movement. This means that the unit forms are transformed in concentric layers. If the starting situation is at a corner of the design, then the pattern is only partially concentric. In concentric movement, the climax may be a point, a square or a cross.

Zigzag Movement. This means that the unit forms of the same step are arranged in a zigzag manner and are transformed at equal speed.

. . . . small standardized gradation patterns may be repeated and arranged to form a bigger pattern of gradation.

. . . . gradation can proceed from the starting situation to the terminating situation and then back to the starting situation with the reversal of the steps... repeated and repeated if necessary, with smooth transitions...... 123451234512345

[Wong, Wucius. Principals of Two-Dimensional Design. New York: Van Nostrand Reinhold Company, 1972.]

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