Lesson #1
Introduction
Perspective, perspective, perspective! I strongly suspect that a good fifty percent of the requests I receive for lesson material is for advice on how to draw and paint in perspective! This seems to be an area that is difficult for the beginning student as well as some more accomplished artists. The subject is all the more complicated by the fact that there are so few books written about this subject and the ones that are available seem to lay out the text in such a way as to make the understanding of it all the more difficult.
In this series I will attempt to give you a very comprehensive look at the problems and ways to cure them. However, it is difficult to lay out the concepts without language that some of you may have difficulty in comprehending. If this is the case for you I encourage you to simply send me an e-mail and I will attempt to help guide you through the maze. Do not be discouraged or feel that you are asking "dumb" questions. Our mission here at Wetcanvas! is to provide art education. Only unwise students remain quite and do not ask questions.
Allow me to apologize in advance for the sometimes poor quality of the illustrations used. These are illustrations that I have used in classes for many years and over that time yellowing has taken place. I have attempted to "clean up" the pages wherever possible and it has also been necessary to transpose electronic lettering where the old type existed. Still, I think that you will be able to work with these images.
If you can successfully complete this series with a decent understanding of the precepts offered, then you will have mastered the art of drawing and painting in perspective. Also, for those of you who may be pondering a career in industrial art, then this series will be of immense value to you. Good luck!
BASIC PRINCIPLES
All ordinary perspective drawing is based upon a simple conception; that, between the eye of the observer and the object to be drawn, there stands a transparent plane, a sort of window, called the "picture plane", on which the form of the object is projected. This picture plane may be a window in the literal sense, and, if you will make the following experiment, the real meaning of the phrase will be much clearer.
Select a window having large, individual panes, and obtain a magic marker. (Also, in order to insure domestic tranquility, it's advisable to have some benzine or paint thinner with which to remove the markings :-) Stand at the window at such a distance that is just convenient and comfortable to mark on the window with the arm outstretched. Keeping the head as nearly stationary as possible, trace on the window the outlines of things seen through it. The result is a perspective drawing on the picture plane itself.
If the image upon the window is now examined, and if it contains buildings or other objects containing straight lines and right angles within its view, several characteristics of that image may be noted, all having the greatest importance in the practice of perspective drawing. First, all lines appear to be shorter than their true length, and the shortening effect increases as the distance of the object line increases. Second, vertical lines, such as tree trunks, corners of buildings, and telephone poles, appear truly vertical, whereas horizontal lines, with the exception of those at the eye level, do not appear horizontal. Third, groups of horizontal lines running in a single direction appear to converge toward a single point. Other groups of horizontals having different directions have different points toward which they converge. Fourth, these points of convergence for horizontal lines all lie on a horizontal plane, level with the eye of the observer. This effect may be seen vividly, even without using a window, simply by looking down a long straight railway track and noting how the rails seem to vanish at a point directly opposite the eye.
Other effects are also noticeable. The apparent shortening of a line seen obliquely is one example. This effect, called foreshortening, is somewhat more subtle, though often more drastic, than that of distance, and it exerts a strong effect on the appearance of the picture. The apparent flattening of circles, resulting in the ellipses that cause students so much trouble, is another. (Strictly speaking, this is also foreshortening.) If there are circles within the view embraced by the window, a study of them alone will be worth the trouble.
The function of the window may be briefly described as follows: Since vision is impossible without light, it is assumed that a ray of light enters the eye from each point on the object. On the way from object to eye, each of these rays pass through or, in technical language, pierces the picture plane. The spot where the ray from any given point on the object pierces the picture plane is the perspective projection of that point. When all the rays from all the (visible) points on the object have produced their perspective projections, the sum total is the perspective projection upon the two-dimensional picture plane of the three-dimensional object beyond. Curves are another matter and we will discuss them in more detail in subsequent lessons.
It is at this point that the artist enters. If he intends a literal transcription of what he sees, he simply transfers to a piece of paper or canvas that projection upon the picture plane. Note that he copies not the object itself (that is possible only in sculpture) but its projection upon the picture plane. In actual drawing, of course, it is impractical to set up a piece of glass between artist and object. The picture plane is purely imaginary, and the artist transfers his impression directly to the paper. Nevertheless, though the picture plane in itself is imaginary, it has a vital function in drawing, just as vital, in fact, as the imaginary lines of latitude and longitude without which navigation would be nearly impossible.
It is
not absolutely necessary to know the theory of the picture plane in order to
make plausible perspective drawings, but such knowledge will make it easier
to understand the rest of the subject. It will also aid in learning to
produce special effects such as the illusion of enormous size, birds-eye
views, etc.
The picture plane is usually considered perfectly vertical, because our upright posture and the position of our eyes forces us normally to look straight ahead. This is the case in the window drawing experiment just described. On the other hand, had the science of perspective been worked out by a bird, we should probably have a convention if a horizontal picture plane. Occasionally it is expedient to assume the picture plane to be neither perfectly horizontal nor perfectly vertical, but tilted. These three alternatives are illustrated in Fig. 1, together with the resulting images. As is to be expected, each produces a perspective image having noteworthy individual characteristics, and each has its special uses.
Figure
1A shows the sort of picture given by the vertical picture plane. The
vertical lines of the object, being parallel to the picture plane, appear
still vertical, still parallel, and still in their true proportions,
(not scale) in the image. Except in the special case of one-point
perspective, which we will discuss in a moment, the other two sets of lines
do not appear in their true directions, parallelism, or scale. Figure 1B
shows the character of the picture obtained with a horizontal picture plane.
Here the verticals loose their original character, while the parallel
horizontals remain parallel and in true proportion. Lastly in figure 1C we
have a case in which the picture plane, not being parallel to any of the
principle lines of the object, produces an image in which no lines
appear as parallels or in true proportion.
The picture plane may also be assumed to be at any given or desired distance from the eye. When it is close to the eye and distant from the object, we see an image small in size compared to the size of the object; when it is close to the object and distant from the eye, the image approaches the actual size of the object. It is even possible to assume for it a position behind the object, in which case we get an enlarged image. This is what the microscope does for us - pushes the picture plane back of the object under examination. In each of the cases shown in Fig. 2 and, as a matter of fact, in all perspective drawings, the rays from the object converging in the eye form a cone with they eye as apex. When, as in Fig. 2A, the picture plane cuts across this cone near the apex, the resulting cross section is necessarily very small. In Fig. 2B the cross section is taken near the larger end and is thus relatively large.
The third position, illustrated in Fig. 2C, calls for some exercise of the imagination. Although the rays do not, in FACT, continue beyond the object, there is no reason why, if it suites our convenience, we should not assume that they do. As will be seen later, this may be of practical value when actual dimensions are too minute for clear and comfortable presentation in a picture.
In any rectangular object there are three sets of parallel lines, mutually perpendicular to each other. These are: first, lines running from top to bottom; second, lines running from side to side; third, lines running from front to back. It was noticed in Fig. 1C, for instance, that each set of lines, actually parallel to the object, tends in the image to converge toward a point in the distance. Since there are three such sets of lines, there are consequently three such points. When the picture plane is parallel to any one of these sets of lines (usually the vertical set as in Fig. 1A), one of the points disappears and the lines in question appear truly parallel in the perspective image. Occasionally the picture plane is parallel to two sets of lines in the object. In this case two of the three sets of lines will appear truly parallel in the perspective, and only one point of convergence is needed.
It is
obviously impossible for the picture plane to be parallel to all three sets.
For this reason it is impossible to make a realistic drawing of a solid
without using at least one such point of convergence, but perfectly
satisfactory pictures of plane objects, such as textile designs, printed
pages, etc., may be, and usually are, made with no such points whatever.
When the picture plane is vertical, the usual case, it is naturally parallel to vertical lines in the object, which appear truly vertical, as in Fig. 3B, and naturally parallel to each other. Moreover, the two vanishing points of the horizontal lines both lie on the same horizontal line. This fact is of great importance in drawing. More about this later. Lastly, when the picture plane is parallel not only to the vertical lines, but to one of the sets of horizontals as well, these horizontals appear as truly horizontal in the image. This case, with the single remaining vanishing point, is shown in Fig. 3C.
When, as often happens, there are sets of lines in an object that are not parallel to the three principle sets listed previously, these lines have separate vanishing points of their own. The peaked roof of a house, for example, requires two auxiliary vanishing points, one for each side. Thus a two-point perspective of such a house would actually have four vanishing points. It is called two-point perspective nonetheless, for only the vanishing points for the principle lines are counted.
Two-point perspective is used in about 90 per cent of ordinary drawings. One-point perspective should be used when only one plane of an object is of interest, and perspective is needed only to suggest depth. Three-point perspective is valuable when we want to suggest the effect of looking down from a great height, such as the top of a tall building or an airplane in flight. It is also useful for the exact opposite, looking up at such a building from the street level.
In this session we have briefly surveyed some of the theory, that is to say, the "why" of perspective - why vertical lines usually appear parallel and in true proportion, why we sometimes tilt the picture plane, etc. The remainder of this series will be largely devoted to technique, i.e., to "how" - how to draw lines in true perspective, how to obtain correct proportions along lines where a scale cannot be used, how to draw a circle seen obliquely, and numerous other problems. This does not mean that we shall cease to consider theory altogether, but that merely from here on it will serve mainly to clarify the principles of practical work methods.
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