SHADE & SHADOWS
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"Shade and shadows" refers to the technique of determining
areas in shade and casting shadows on surfaces by means of
projection drawing. The depiction of light, shade, and shadow can
model the surfaces of a design, describe the disposition of its
masses. and articulate the depth and character of its details.
• The light source for architectural shade and shadows is
assumed to be the sun. The sun is so large and distant a
source that its light rays areconsidered to be parallel.
• The sun angle is the direction of the sun's rays, measured in
terms of either bearing or azimuth and altitude.
• Bearing is a horizontal angular direction expressed in degrees
east or west of astandard north or south direction.
• Azimuth is ahorizontal angular distance, measured clockwise,
of a bearing from due north.
• Altitude is the angular elevation of the sun above the horizon.
Shade refersto the relatively dark area on those parts of a
solid that are tangent to or turned away from a theoretical
light source.
• Shadows are t he relatively dark figures cast upon a surface by
an opaque body or part of a body intercepting the rays from a
theoretical light source.
• A shade line or casting edge separates an illuminated surface
from one in shade.
• A shadow line is the shadow cast by a shade line on areceiving
surface.
• A shadow planeis a plane of light rays that passes through
adjacent points of a straight line.
• Every part of an object in light must cast a shadow. The
corollary t o this is that any point that is not in light cannot
cast a shadow because light does not strike it.
• A shadow is visibleonly when t here is an illuminated surface
to receive the shadow. Ashadow can never be cast on a
surface in shade, nor can it exist within another shadow.
Digital Shade and Shadows
Modeling software typically includes the ability to specify the
location and orientation of the light source and to cast shade
and shadows automatically.
14 4 /ARCHITECTURAL GRAPH ICS