Shading

Shading refers to the depiction or control of light and darkness on a surface to convey volume, form, and depth. It can describe both the illusion of light in two-dimensional art and the real or simulated modification of light in three-dimensional scenes. In everyday usage, shading is distinct from a shadow; a shadow is a region of reduced light cast by an occluder, while shading describes how light interacts with a surface to produce gradations in tone.

In traditional drawing and painting, shading is created by varying value, saturation, and color temperature. Common techniques include hatching, cross-hatching, stippling, and blending to build smooth or textured tonal transitions. Artists use value scales and light source consistency to achieve realism or stylized effects, with chiaroscuro being a well-known approach to strong contrasts between light and dark.

In computer graphics, shading describes how a surface responds to light in a scene. Models include flat shading, Gouraud shading, and Phong or Blinn-Phong shading, and physically based rendering aims to simulate realistic illumination. Shading calculations combine ambient, diffuse, and specular reflections, often using surface normals, light direction, and material properties. Advanced techniques include normal mapping and shadow mapping.

Shading also plays a practical role in architecture and design. Shading devices such as overhangs, louvers, screens, and vegetation reduce solar heat gain and glare. In horticulture, shading systems and shade cloth regulate light exposure to crops and protected environments, supporting plant health and growth.

Across contexts, shading influences how colors and textures are perceived by human observers, affecting mood, contrast, and readability of forms.