sisting of highlights and shadows. A change
in this pattern, caused by a change in the
direction and distribution of light, alters
visual impressions of form and surface.
Lighting alters perception of texture.
Grazing light, from luminaires located close
to a surface being lighted, strengthens high-
lights and shadows. It enhances the percep-
tion of depth by emphasizing the natural
textures and sculptural relief of the surface.
Grazing light is also used for inspection to
detect surface blemishes and errors in work-
manship (figures 3.21 and 3.22).
Grazing light is appropriate for lighting
heavily textured surfaces such as rough plas-
ter, masonry, or concrete. It is disastrous for
“flat” walls of smooth plaster or gypsum
board, however, because such walls are notBRIGHTNESSFigures 3.21 and 3.22Grazing illumination.
Figures 3.23 and 3.24Diffuse wash light.