Types of Views 101
The same dimensioning rules that apply for an orthographic/multiview drawing also apply to a pic-
torial drawing. These include:
- Dimension and extension lines should be drawn parallel to the pictorial planes.
- When possible, dimensions are placed on visible features.
- Arrowheads lie in the same plane as extension and dimension lines.
- Notes and dimensions should be lettered parallel to the horizontal plane.
The three main types of pictorial drawings that are extensively used in architectural presentations
are perspective drawings, isometric drawings, and oblique drawings.
The main difference between isometric and typical perspective drawings is that in the latter the lines
recede to vanishing points. This gives the drawing a more realistic appearance but is technically inac-
curate. Isometric drawings, on the other hand, show true dimensions. However, they create an optical
illusion of distortion, mainly because the human eye is accustomed to seeing long object lines recede.
For this reason, isometric drawings are primarily utilized for clarification of small construction details,
since they depict their true size dimensions. In an oblique drawing two or more surfaces are shown at
one time on one drawing. The front face of an object is drawn in the same way as the front view of an
orthographic sketch.
5.8 PERSPECTIVE DRAWINGS.
A good understanding of the principles of perspective is necessary to create an accurate and visually
appealing piece of art. Perspective drawings are forms of pictorial drawing. Blueprint readers may not
see a perspective drawing very often, but they will undoubtedly appreciate the descriptive information
it offers. Perspective drawing is a system for representing three-dimensional space on a flat surface.
It utilizes either one, two, or three points to where the receding lines will vanish. These vanishing
points are placed along a horizontal line called a horizon line. In perspective drawings receding lines
are no longer parallel to each other as in oblique or isometric drawings.
In perspective drawings, distant objects appear smaller but have the same shape and proportions
as they would close up. In other words, as objects are further away, they become smaller and appear
to vanish into the distance. The general principle behind perspective drawing is simple and shares
many features with the way people actually perceive space and objects in it. It depends essentially on
four interconnected criteria that will invariably affect the final image: the level of our eyes when view-
ing the scene or object, thus determining the horizon line; the distance from the picture plane to the
object; the distance from the station point to the object and cone of vision; and the angle of the object
to the picture plane.
Perspective drawings may be drawn as impressive artistic renderings to show landscapes or large
structures. They can also be used to show a realistic representation of machine parts or layouts of ar-
chitectural furnishings in a room. Perspective drawings are more difficult and time-consuming and are
not used as extensively as they might be. They are used mainly for illustrative purposes, but their use
as a descriptive drawing in manufacturing environments should not be overlooked.
In essence, there are three basic types of perspective drawings that are commonly used in ar-
chitectural design and construction: one-point perspective, two-point perspective, and three-point
perspective.