Graphics Reference
In-Depth Information
Chapter 3
Made Modern
In 1525, Albrecht Dürer made a woodcut demonstrating a method by which one
could create a perspective drawing of almost any shape (see Figure 3.1); in the
woodcut, two men are making a drawing of a lute. In this chapter, we'll develop a
software analog of the method depicted by Dürer.
The apparatus consists of just a few parts. First, there is a long string that
starts at the tip of a small pointer, passes through a screw eye attached to a
wall, and ends at a small weight that maintains tension in the string. The pointer
can be moved around by one person to touch various spots on an object to be
drawn.
Second, there is a rectangular frame, with a board, which we'll call the shut-
ter, attached to it by a hinge so that the board can be moved aside (as shown in
the woodcut) or rotated to cover the opening, as a shutter covers a window. On
the board is mounted a piece of paper on which the drawing is to be made. In the
woodcut, you can see a drawing of a lute partially made on the paper. The first
man has moved the pointer to a new location on the lute itself. The string passes
through the frame, and at the point where it does so, the second man holds a pen-
cil. The string is pushed aside, the shutter is closed, and the pencil makes a new
mark on the paper. This process is repeated until the whole drawing (in the form of
many pencil marks) emerges. The man holding the pencil must hold it very steady
for this to work, of course!
The result is a drawing of the lute consisting of many pencil marks on the
paper, which can be connected together to make a more complete drawing. The
drawing is a perspective view of the lute, showing the way the lute would look to a
viewer whose eye was at the exact point where the string passes through the screw
eye on the wall. Note that the height of the screw eye on the wall and the position
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