What are the types of light sources?

In the world of computer graphics, light sources play an essential role in bringing realism and visual appeal to the computer-generated environment.

Whether you are looking to recreate the sunset or the diffuse reflection of a cloudy day, understanding different types of light sources can help you achieve the desired effects. Each type of light source has its own unique characteristics and uses.

Types of light sources

The most common types of light sources are explained below.

Ambient light source

• Provides uniform light in all directions, modeling inter-reflections.

• Does not have a specific direction.

• Ensures that no part of the scene is entirely in the dark.

• Does not contribute to the shadow of an object.

Directional light source

• Emits parallel rays as if the source is infinitely far away from all the surfaces in the scene

• Direction of light is constant for all surfaces in the scene

  • Light position is not important.

  • Viewer position is not important.

  • Surface angle is important.

• Create shadows based on its direction despite its infinite distance

Point light source

• Emits light equally in all directions from a single point, similar to a light bulb

• Direction of the light is different for different points

  • Light position is important.

  • Viewer position is important.

  • Surface angle important.

• A normalized vector is calculated for every point we light by using the formula given below.

Where,

• $b$ is the point of the light source

• $c$ is the point on the surface

• Light attenuation is the brightness or intensity of the light source, diminishing with distance.

  • As light travels through a medium or space, it encounters particles or objects that can scatter or absorb light, decreasing its intensity with increasing distance from the source.

  • So, the objects may appear less bright when they are farther away from a light source.

• Light attenuation is calculated as given below.

• The light is brightest at the source $b$ and diminishes as we move away.

• It gives the scene a more realistic appearance.

Spotlights

• Spotlights are the point light sources.

• Have directionally falling intensity.

• Define cutoff angle for the spotlight.

Area light source

• Defines a 2D emissive surface, like a disc or polygon.

• Example: fluorescent light panels.

In conclusion, understanding the nature of point light sources and their mathematical models is essential for creating realistic illumination effects in computer graphics.

Continue reading

• What is diffuse reflection?

• What is Lambert's cosine law?

• What is bilinear interpolation?

• What are barycentric coordinates?