Selected Bibliography Architectural Graphics | Seite 98

PICTORIAL EFFECTS OF PERSPECTIVE

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The convergingnature of sightlines in linear perspective
produces certain pictorial effects. Being familiar with
these pictorial effects helps us understand how lines,
planes, and volumes should appear in linear perspective
and how to place objects correctly in t he space of a
perspective drawing.

Convergence
Convergence in linear perspective refers to the
apparent movement of parallel lines toward a common
vanishing point as they recede.
__ .--· ·• As two parallel lines recede into the distance, the
----···
space between them will appear to diminish. If the
lines are extended to infinity, they will appear to
meet at apoint on the picture plane (PP). This point
is the vanish ing point (VP) for that particular pair of
lines and all other lines parallel to them.
- ... The vanishing point (VP) for any set of parallel lines is
the point where a linedrawn from the station point
(SP) parallel to the set intersects PP.

The first rule of convergence is that each set of parallel
lines has its own vanishing point. A set of parallel lines
consists only of those lines that are parallel to one
another. If we look at a cube, for example, we can see
that its edges comprise three principal sets of parallel
lines, one set of vertical lines parallel tothe x-axis, and
two sets of horizontal lines, perpendicular to each
other and parallel to theY· and Z-axes.
Inorder to draw aperspective, we must know how many
sets of parallel lines exist in what we see or envision
and where each set will appear to converge. The
following guidelines for the convergence of parallel lines
is based solely on the relationship betweenthe
observer's central axis of vision and t hesubject.

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I ARCHITECTURAL GRAPH ICS