Reflection

Reflection is the light phenomenon that occurs when a light ray bounces of an object. If the surface is very smooth, the reflection angle will be the same as the incident angle as shown in figure below. This type of reflection is called specular reflection. We experience specular reflection when we look at a mirror or the surface of a body of water, for example.

In contrast, diffuse reflection occurs when the surface is rough and light is scattered in all directions as illustrated below. This is the most common type of reflection which we experience whenever we look at a matte object such as gypsum board. Many real materials show a combination of diffuse and specular reflection, for example, painted wood or plastics. For the metal plates of sol.id, it is essential that we obtain the best specular reflection possible, so that sharp images of the portraits are created.

Caustics

Light reflected (or refracted) from a curved specular surface can create interesting light patterns that we commonly observe in the world around us, as illustrated in the photographs below. In particular, glass windows, water surfaces, or shiny metal objects often create seemingly random reflection or refraction patterns on surfaces nearby. In computer graphics, these patterns are generally referred to as caustics. In optics, the term caustics is used more restrictively to describe the envelope of a family of light rays created by reflection or refraction.

The illustration below shows how the curvature of the reflecting water surface redirects the incident light rays to create a non-uniform light density on the receiving wall surface. The challenge of caustic design is to compute a reflecting or refracting surface that will create a predefined image. We solve this problem with a new algorithm that calculates an inverse light simulation. For more information on this algorithm, please click here.