How does lighting change the appearance of objects in computer graphics?

In computer graphics, lighting is essential for defining the visual appearance of objects beyond their basic shape and color, as it dictates how surface finishes—such as matte, satin, or glossy—are perceived. The interaction between illumination and these surface attributes determines the final rendered look.1

Several techniques are used to simulate these effects:

• Shading Techniques: Simple methods like flat shading apply a single color tone to an object, resulting in an unrealistic appearance. More advanced methods like Gouraud shading interpolate colors across faces to create smooth gradients, while Phong shading calculates lighting for each individual pixel, providing greater realism.1
• Ray Tracing: This technique uses optical laws of reflection and refraction to model how light behaves when it hits surfaces, allowing for the rendering of specular reflections on glossy objects and the appearance of transparent or translucent materials.21
• Radiosity: Unlike ray-based models, radiosity treats light as energy. It accounts for diffuse light reflected from other objects in a scene, such as a colored object casting a subtle glow onto surrounding surfaces, which creates a more physically accurate representation of light interaction.21