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Technology: Engineering Our World
Perspective sketching provides the most realistic picture of objects. g
The sketches are drawn to show objects as we would actually see them.
Parallel lines converge and vertical lines become shorter as they disappear
into the distance. Refer to Figure 3-22 as you read the following steps for
drawing a perspective sketch of a block:
1. Draw a faint horizontal line to represent the horizon. Mark two
points, one at each end of the line. These are vanishing points (VP).
2. Draw the front vertical edge of the block.
3. Draw faint lines from each end of the vertical edge to the vanishing
points.
4. Draw vertical lines to represent the left and right edges of the block.
The length of these vertical sides will be shorter than the real object.
5. Join the top of these vertical lines to the vanishing points. Darken
the outline of the object.
Orthographic Projection
You have learned that isometric and perspective sketches are quick
methods of recording your ideas and communicating them to other
people. They give a general idea of the shape and features of an object.
Unfortunately, there are some disadvantages to isometric and perspective
sketches. For example, they do not describe the shape of an object exactly
because of distortion at the corners, nor do they provide complete
information for the object to be made.
gure 3-21. In real life, objects at a distance seem narrower or shorter than they are close up.