Learning Event 2:
IDENTIFY COMPOUND FORMS
1. Compound Form.
Most objects consist of compound forms that can be
reduced to a basic form, as you've just seen. You can solve most of your
perspective problems if you understand the cube and its relationship to
perspective. The three most important things to remember are: the horizon,
the station point, and the vanishing points.
These are the only elements
that affect the appearance of your drawings. If these elements are poorly
selected but definitely established, your drawing is correct although it may
be unattractive.
a. Remember, keep the vanishing points as far apart as possible; this
gives the final picture a more pleasant appearance. Also keep all vertical
lines truly vertical, except for special effects.
If special effects are
necessary, a third vanishing point may be needed.
b. Drawing a cube or a rectangle in perspective is a simple operation
if you understand measurement. A rectangle in perspective can be thought of
as two cubes placed end to end. If you can draw a cube and measure it, you
can divide it into halves, thirds, or any number of divisions found in
compound form. Compound forms need not be complex if they are thought of as
cube-upon-cube in perspective.
2. Making a plan and elevation view. Plan and elevation views can become
very complex; compound forms are to be expected. When making such a plan
and elevation view in perspective, the-first step is to draw a line to
represent the picture plane. The plan view is arranged behind the picture
plane with the nearest corner of the building just touching the picture
plane (A) as shown in Figure 3-6. Next, select the station point. Make the
station point approximately the center of the plan view at a 30 overall
angle.
a. Draw lines from the station point to the corners of the important
parts of the building that you want to locate in your perspective drawing.
Where the lines intersect the picture plane, draw vertical lines to
establish accurately the width of the different parts of the structure. The
most important of these lines is the line that is actually touching the
picture plane (line A).
It is the only line that is not foreshortened;
therefore, it is the only line that can be used for vertical measurement
from the elevation view.
b. Now you must decide on the location of the horizon line. After you
have located the horizon line, draw lines (B) and (C) parallel to lines (D)
and (E) in the plan view.
From the points at which lines (B) and (C)
intersect the picture plane, drop vertical lines to the horizon line to
establish the right and left vanishing points.
c. The next step is to carry across vertical measurement from the
elevation view to line (A) and draw construction lines from the points on
line (A) to the vanishing points using the same procedure already discussed.
The vertical lines dropped from the picture plane will automatically
establish the width of doors, windows, walls, etc., in the perspective
drawing.
Remember, you can make direct vertical measurement only on line
(A); it is the only true length line in the whole drawing.
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