Shading involves two concerns: actual technique and values. Contour line is where most people begin a drawing. Since line is all about the edges, they can lack the appearance of dimensionality. When you shade your drawings, you create a more obvious illusion of volume.
The purpose of shading is to “sculpt” forms from out of the paper or canvas to create volumetric illusion. In order to shade effectively, we first need to understand what form is and how we see it.
Form is defined as the visual appearance of something. It’s a three-dimensional concept. Forms are three-dimensional objects (also architecture, animals and people) made up of shapes. When we view a form, we can’t see the entire thing at once. To see it all, we need to rotate it, or — if it’s a large form such as a human being or a car — walk around it.
There are various types of forms:
organic natural forms such as human beings, trees, animals, fish,
abstract stylized or simplified from natural form
representational represent natural form directly
non-objective the form is created for utilitarian or aesthetic purposes
crystalline multi-faceted (many faces)
geometric mathematically precise forms: sphere, cylinder, cube, Platonic solids, Archimedean solids
No matter what the variety of form, light and shadow work together to reveal it to us.
Light and shadow follow a logical pattern.
Shading depicts the relationships between light and shadow. When light hits a form, certain things happen that you can rely on. Once you understand the regular patterning of these relationships, you can shade anything convincingly.
The Light Area
There is the direct or center light area where the light hits the surface straight on.
Within the center light area sits the highlight — the area where the light is most luminous. Shiny objects have a very pronounced highlight. Softer-textured objects have subtle highlights. The highlight follows you around the form.
The Form Shadow
Where the form begins to turn away from the light is where the halftone exists. This is the transitional area that’s only half-lit; it’s the start of the form shadow’s territory.
Getting the core shadow right is a key concern when you’re depicting volume.
Without it, forms will appear flat.
Moving farther into the form shadow we encounter the core shadow — the darkest part of the shadow. Getting the core shadow right is a key concern when you’re depicting volume. Without it, forms will appear flat.
On the other side of the core shadow is the reflected light caused by light bouncing into the shadow from nearby surfaces.
The Cast Shadow
Cast shadows occur when forms block the path of light. We use them to help communicate the shape of the form and its relationship to the surrounding space.
Cast shadows are not a single, solid color. Within the cast shadow we find lighter and darker areas. The darkest area is call the occlusion shadow. Cast shadows have sharper edges close to the form, and softer edges farther away from the form where there is more light bounce.
Learn more about light and shadow. Read Introduction To Light Logic
Start simply, then build complexity
To shade complex forms, first think abstractly. Simplify the form to essential geometry.
When you simplify an organic form, or abstract it, you’re reducing the number of planes the form is made of. Planes are flat, two-dimensional areas. The more planes in a form and the smaller they are, the more “round” the form appears.
Then, figure out basic light and shadow relationships. Where is the break between the center light and the from shadow? What’s the overall shape of the shadow and the lit area?
The development sequence above begins with a gestural line sketch (left panel) to decide shape, proportion and movement.
The light source is coming from our top left.
Basic light and shadow shapes are decided, including reflected light areas and form shadow (center-left panel)
Shadow and light areas are built up (center-right panel)
Details are refined (right panel)
Once you determine the basic light and shadow shapes, you can build detail, breaking up that initial simplified shape into its smaller parts and assigning light and shadow relationships within each.
Focus on light and shadow, not local color
To draw a three-dimensional form on a two-dimensional surface and make it convincing, focus on light and shadow values, not color breaks. A blue sphere and a white sphere are different in color, but the light and shadow relationships are the same between them. If a sphere is multi-colored, light and shadow affect the appearance of the various colors.
Related Reading: Fundamentals of Value Contrast
Edges on forms can be soft or hard, or somewhere in between. As you gain skill and confidence you can use these edge contrasts to your advantage in depicting form.
Sharp corners should be drawn with hard edges (contour line). A slightly rounded edge will need a softer line, and broader. A sphere will need a soft edge.
Edit light sources
When you draw from photos or from life, multiple light sources may be present. Your task is to edit, and ignore all but the most relevant light source for depicting the form.
In photos, multiple cast shadows going in multiple directions are not a problem, but they don’t translate well to depicting form in drawing and painting. So, don’t include what you don’t need.
By eliminating excess light sources, you’ll simplify your drawings and make them stronger in how they communicate.
Strong light results in strong shadows. On an overcast day, light is diffused and shadow are soft. Forms appear flat. If you’re shooting a portrait, the diffused light is helpful for reducing the appearance of wrinkles.
However, in a drawing, lack of light–shadow contrast will flatten your form. A strong direct light source is necessary to create a convincing volumetric illusion — the appearance of three-dimensional form on a two-dimensional surface.
Even if you don’t actually see these strong contrasts, you can include them to create a more compelling image.
Tools and materials used in the illustrations
What questions do you have about shading your drawings?