Scribe a circle from the center vanishing point (CYP) to the points
where the lines meet the horizon line
(HL).
r - - - - - - - - - - - - -----
4. Check that the drawing surface is
three times the diameter of this circle. Mark the 60° points on HL.
5. Mark the 45° and l5° points on HL
using angles of SP.
Approximating the 7S ° VP
The 75° YP is approximated because it is roo far off the board to be
conveniently reached. To make the
grid:
A. Erect a vertical at the 30° YP (edge
of the 60° cone of vision) to the 75°
line.
B. Use the measurement from SP to
CYP and lay this measurement from
the intersection of the 75° line and
the vertical from the 30° (A) to the
point where the line meets HL (B).
C. Mark the same units on SP-CYP
and A- B.
D. Project these points from A - B to
the vertical at 30° YP. These are the
diminished units.
E. Connect these to the units at the SPCYP beginning at the HL.
F. Repeat for the other side and below
the horizon line.
The grid is now ready for sketching.
The sketch is made on top of this grid
on tracing paper.
Scale of Objects
In practice the scale of objects is as
important as the perspective system
itself. Error in scale can provide as
many distortions as errors in perspective. The 30" cube is the standard unit
of measure. It is half the height of a 5 I
person. It is also the height of a club
chair arm, the width of a standard
door, and the depth of a couch. Half
the height of the cube is the standard
15" seat. A 15" cube represents the seat
of a diningroom chair. Objects should
be studied and measured against the
30" cube.
1\lark a ground line 5 I in scale belo\\'
HL. This is 60", the height of an average person, and twice the height of a
30" cube in the selected scale. A line
anywhere from the horizon represents
---
r-------. ____
!'
I
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-
I
,
F--
1/
H
I
. c = p.=
j-----
II
~~~
I I
r------
I
I
I
I
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fill
.---
'1
"
1/
,,/'/
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~
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/" ~1
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k::.-... ~
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The scale of {he s{udel/{ drawil/g is correCied by drawil/g {he chairs 01/30" cubes.
SITT Fall 198-l/Theatre Design & Technology
9