BUILDING A DRAWING
layering Tonal Values
In composingand establishing the structure of adrawing, we
create a framework of lines. T this scaffolding, we add tonal
o
values to represent light and dark areas of the scene, define
planes in space, m their form, describe surface color and
odel
texture, and convey spatial depth.
\\ ~
'
Work from light to dark by mapping layering shapes of tonal
value over preceding areas of value. If an area istoo light, we
can always darken it. But once an area has been darkened too
much and becomes muddy, it is difficult to correct. The
freshness and vitality of a drawing is fragile and easily lost.
• Shaded surfaces and cast shadows are neither opaque nor
uniform in value. Avoid employing large areas of solid dark
tones, which obliterate detail and disrupt our reading of the
form of asurface.
• Light reflecting back from nearby surfaces illuminates
surfaces in shade or on which shadows are cast. To depict
the modifying effects of reflected light, we vary the tonal
value of surfaces in shade and those onwhich shadows are
cast. The effects of reflected light, however, should be
suggested in asubtle way, so as not to disrupt the nature
of the surface in shade or shadow.
• Shades and shadows can be appl ied as transparent tones
t hat belong to the form and through which we can read the
texture and local color of the surface.
• The boundaries of cast shadows are distinct in brilliant
light, but softer in diffuse light. In either case, we can
define the outer edges of shadows with acontrast in value,
never with a drawn line.
• The way light illuminates a color and makes it visible affects
its apparent value. A highlight on a colored surface will
appear much lighter than the same hue seen in shade or
within a shadow.
198 /ARCHITECTURAL GRAPHICS