Rendering, Modeling Tone and Indirect Lighting

Indirect Lighting and Modeling Tone
The first half of this manual has been primarily concerned with creating form using line. In reality, we see things primarily in tone, not line. I have used tone in many of my examples to define the forms without explaining the usage. In this lesson, and the next two, we will discuss three distinct methods of using tone. The three approaches, which are indirect lighting, direct lighting, and atmospheric perspective, are distinct but generally used in varying degrees together. For the purpose of teaching, I am focusing on each one as a separate and distinct approach.

The clarity of an edge of a form is defined by what is behind it. The greater the contrast the clearer the contour. A solid black object against a white background can appear quite flat without a light source defining the interior corners and the parts that come forward (see Illustration A). To create a strong sense of volume it is necessary to emphasize these internal corners that come forward and subordinate those that recede back in space.

Indirect Lighting
Indirect Lighting

Illustrations B, C, and D demonstrate the fundamental elements of the indirect lighting approach. The part that is facing you is the lightest and the form becomes darker as it turns away from you. Notice that I said, “Turns away from you.” The important point here is the angle of the form in relationship to you. In Illustration C, the outside contour has also been softened to make it recede even more.

What faces you is in light; what turns away from you is in tone. Another way of thinking about this is to imagine yourself as the source of light.

Indirect Lighting 2
Indirect Lighting 2

Illustration E gives an example of this basic principle. Remember, it is the angle that a particular surface plane faces that determines its value (degree of light and dark), not how far away from you it is.

This use of tone, or value, is usually referred to as a “modeling tone.” We model the form using the tone to define itself in space in the same way a sculptor does. Since our main concern is to describe form, you must look at the basic procedure as a tool rather than a rule. We use the tone to push the sides back on a form.

Let us modify the basic concept now to read: “What faces you, relatively, is in light; what turns away from you is in tone.” The word “relatively” is very important. Study Illustration F. This is actually an optical illusion. The forms can be seen going in or coming out. The parts of the forms that are in light do not actually face you, but, relative to the forms that are turned more away, they do. Notice that there is no difference between those forms that are close to you and those farther away. Of course, in reality, there is, but for the moment concern yourself only with the angle that the plane of the form is facing.

The Importance of Values
Before we go any further, you need to develop some basic skills in working with values. One of the most fundamental skills that you must develop as an artist is to be able to recognize and put down values with control.

Drawing Values
Drawing Values

The illustration gives you examples of a few basic exercises that you should do. As a working artist, with over forty years of experience, I still feel it necessary, at times, to do variations on these exercises today.

It is important that you develop the skill in being able to put down a flat and even value. We are interested in seeing the value, not the technique.

Every irregularity or change in tone communicates a change in the form. Do not draw dark lines between values. A line between values will distort the relationship of one value to another and make it difficult to see their relationships. Each degree, or step, of contrast between values should be equal in contrast. Do not underestimate the difficulty or importance of this exercise. It could take hours to do it right.

Practice drawing simple forms from imagination. Redraw some of the forms created in Chapters Two (Spherical Forms) and Three (Box Forms), using tone, but no line. Remember, we are using a specific approach to modeling form. We are not copying the patterns of light and dark that we see on the model. We are analyzing the forms of the model but are not necessarily using the tones that we see on the model. As I have said repeatedly, “Don’t copy the model; analyze.”

Adding to the Basics...
After you have become comfortable using the modeling tone, as we have discussed so far, you can start adding some variables that will give your drawings a more natural look. The first of these variations is to make the tone stronger on one side or the other consistently.

Indirect Lighting 3
Indirect Lighting 3

Look at the spheres to see the difference. The far left is the way we have been doing it; the other is an example of emphasizing one side to give a feeling of a light source other than from directly ahead. A light source from directly in front is sometimes referred to as “flat lighting.” In general, you will find that favoring one side or the other will give a stronger feeling of relief or depth. In essence, you are shifting the light source to one side.

We started this lesson drawing with no distinction in the distance of a form from you, concentrating on the angles of the various planes to establish the tone. In the beginning of this chapter, I mentioned that we will be discussing three distinct approaches, “indirect lighting, direct lighting, and atmospheric perspective,” and that, in practice, we usually use all three methods together to various degrees.

In that context, we are now going to use some of the basic elements of atmospheric perspective in conjunction with the modeling tone. In Chapter Twelve we will bring in many more elements of atmospheric perspective than we have discussed in this chapter. The basic concept of atmospheric perspective is that the farther something is away from you, the more atmosphere there is between you and the form. The closer something is to you, the sharper it will be, the more detail it will have, and the greater the contrast will be; the darks are darker and the lights are lighter. As the forms recede back, the lights and darks become closer in value and you lose contrast and detail. A foggy or smoggy day gives you a perfect example of this concept.

Atmospheric Perspective
Atmospheric Perspective

The forms do not have to have great distance between them. A simple overlap can become an excuse for using this concept. In Oriental landscapes, as well as in Cubist paintings, this approach has been used as a basic method of showing space and separating forms.

In a continuously receding flat form, the leading edge should be darker. This idea is carried over into drawing boxes and cylinders.

In the next lesson, we will be discussing direct light. To use direct lighting, you must first have a good understanding of indirect lighting. Practice creating forms from imagination and rendering them until you have a thorough grasp of the elements discussed.

By Glenn Vilppu

This article first appeared in Animation World Magazine, December 1, 1999. This was taken from the tenth in a series of articles on drawing for animation. In these articles I will be presenting the theory and practice of drawing as a “how to” instructional series. The lessons are based upon the Vilppu Drawing Manual and will in general follow the basic plan outlined in the manual. This is the same material that I base my seminars and lectures on at the American Animation Institute, UCLA, and my lectures at Disney, Warner Bros. and other major studios in the animation industry, both in the U.S. and their affiliates overseas. If you have not seen the previous lessons starting in the June 1998 issue of Animation World Magazine, it is recommended that you do. The lessons are progressive and expand on basic ideas. It is suggested that you start from the beginning for a better understanding of my approach.

Glenn Vilppu teaches life drawing at the American Animation Institute, the Masters program of the UCLA Animation Dept., Walt Disney Feature Animation, Warner Bros. Feature Animation, Dreamworks and Rhythm & Hues Studios. Vilppu has also worked in the Animation industry for 18 years as a layout, storyboard and presentation artist, most of this time was spent working at Disney. His drawing manual and video tapes are being used worldwide as course materials for animation students. Glenn Vilppu has, in effect, either through teaching them directly or teaching their teachers, trained an entire generation of professional animators.