Light and Shadow

Light plays a decisive role in human vision. We see the world around us because light reflected from various objects reaches our eyes. An artist should therefore understand the basic principles of how light falls on surfaces and is reflected from them.

Thanks to this knowledge, we can construct various volumetric forms on a two-dimensional sheet of paper.

So, let’s take a closer look at the principles of light and shadow in the visual arts.

We can conditionally distinguish two types of light – directional and diffused.

Directional light has a pronounced direction. Bright sunlight or light from a small lamp can be examples of directional light. Such lighting usually creates stronger contrasts between light and shadow and makes their boundaries easier to observe.

Diffused light, in contrast, comes from many directions and produces softer illumination. For example, this can be light from a large window or the light of an overcast sky. Such lighting creates less contrast and smoother transitions between light and shadow.

In addition, lighting can be natural or artificial. Natural illumination comes primarily from the sun and from sunlight reflected by the sky, clouds, or the moon. Artificial illumination comes from candles, torches, light bulbs, car headlights, and other man-made light sources.

Because the sun is extremely far from us, its rays can be treated as approximately parallel when drawing objects on Earth. Light from nearby sources, such as lamps or candles, spreads outward from the source, so the direction of the rays changes across the illuminated scene.

The intensity of illumination depends on the strength of the light source, the distance between the object and the light source, and the angle at which the light strikes the surface.

In addition, the perception of an object’s contrast depends on the distance between the object and the viewer. In general, distant objects appear less contrasted and less distinct. We talked about this in our article on aerial perspective.

When drawing, it is also necessary to take into account the physical properties of objects, especially their ability to absorb and reflect light. Matte and glossy surfaces look different under the same lighting. The appearance of an object’s tone depends on its local color, surface texture, reflectivity, and illumination.

Tone is the relative degree of lightness or darkness in an image. Tonal value describes how light or dark a particular area appears. This, together with all the factors mentioned above, affects how an object looks under different lighting conditions.

On an illuminated object, we can distinguish light, form shadow, and cast shadow. Within the illuminated area, we can also observe highlights, lighter planes, and halftones.

A highlight is a bright reflection of the light source on the surface of an object. Its position depends on the relationship between the light source, the surface, and the viewer. The appearance of the highlight also depends strongly on the surface texture. Smooth and glossy surfaces usually produce smaller and brighter highlights, while matte surfaces produce softer and less distinct reflections.

The halftone is the transitional area between the more directly illuminated part of an object and its form shadow. The unlit side of the object is called the form shadow.

On rounded forms, the core shadow is usually the darkest band of the form shadow near the transition from light into shadow. The boundary between the illuminated and shadowed parts of the form is called the terminator.

A shadow cast by an illuminated object onto another surface is called a cast shadow. Its shape depends on the form of the object, the receiving surface, and the position and size of the light source. With a nearby light source, the cast shadow can expand as it moves farther from the object.

In addition to direct light and shadow, we can observe reflected light. Reflected light enters the shadow side of an object after bouncing from surrounding surfaces. Its strength and color depend on the surrounding objects, their brightness, and their reflectivity.

Transitions from light to shadow depend strongly on the form of the object. On rounded objects, these transitions are usually gradual, while on objects composed of flat planes, tonal changes can occur much more abruptly at the edges between planes.

Because a sphere has a continuously curved surface, the transition from light to shadow is smooth. The core shadow forms a darker band on the shadow side, while reflected light from the surrounding environment can slightly lighten the area farther into the shadow. Near the point where the ball touches the surface, the values usually become darker because less reflected light reaches this enclosed area.

The cone has a wide base that gradually tapers toward the top. Because its curved surface changes direction around the central axis, the transition from light to shadow is generally smooth. However, the distribution of tone changes along the cone as its surface narrows toward the tip.

Unlike rounded surfaces, angular forms consist of separate flat planes. On such geometric forms, changes in tone often coincide with the edges where one plane turns away from the light and another begins. For this reason, the tonal contrast between adjacent planes can be much sharper than on rounded forms.

Let’s now look at light and shadow using a more specific example. As you can see, one of the darkest areas is directly beneath the ball, where very little direct or reflected light reaches the surface.

This dark contact area is usually called the occlusion shadow. The cast shadow is also darkest and sharpest close to the object and generally becomes softer as it moves farther away, especially when the light source has a noticeable size.

The appearance of a cast shadow changes with the distance from the object and with the size and position of the light source. Its edges may become softer farther from the object because a larger penumbra develops.

When drawing, it is also necessary to remember that the intensity of light from a nearby source decreases as the distance between the source and the object increases. As a result, objects farther from the source receive less illumination. Understanding this effect helps you organize tonal relationships and create a more convincing sense of space.

As you can see, all these principles apply not only to simple geometric forms. We use them as examples because the main areas of light and shadow are especially easy to observe on simple shapes. Once you understand these basics, you can apply the same principles to much more complex objects.

All these principles are extremely important for any artist. By learning how light behaves on different forms and surfaces, you can depict objects with a much stronger sense of volume and realism.