It is unnecessary to fill each cross-point
of the invisible grid to maintain the order
supplied by that pattern. With the round-
aperture luminaires in figure 13.6, spacing
at the perimeter is half the spacing of the room
to provide uniform wall lighting with open-
reflector downlight/wall-wash luminaires.
Architectural Surfaces
When the primary emphasis of lighted space
is within the visual field, the resulting pat-
terns of brightness reinforce our priorities for
defining space (orientation) and defining
activities (participation).
People define their environment through
a process of additive perception. Information
is gathered by scanning the boundaries of a
space, thereby forming a concept of direc-
tion and limits. When the lighting system is
designed to establish the physical bound-
aries of a space, it helps people to maintain
a sense of direction and an understanding of
spatial form with minimal distraction from
the environment.
Lighting helps to define and separate
the major surfaces of a space if the shape of
the light distribution relates to the form of
the surface. For example, a wall or ceiling
lighted with a uniform wash of light will
approximate the form and dimension of that
surface.
A linear wash of light facilitates clear
visual separation between the vertical and
horizontal planes (the wall and ceiling sur-DESIGNFigure 13.66-inch-diameter round-
aperture luminaire pattern.