There are a few exceptions however and one of them is metals. This is visible in the example above, where the ball is still tinted red, but as it is a tinted mirror, its own color shows much less. It is important to note that because very smooth surfaces reflect light perfectly, they reflect much less of their own color. Specular reflection is the perfect, mirror-like reflection of light from a surface, in which light from a single incoming direction is reflected into a single outgoing reflection, as for example with a mirror (above right). Many rough surfaces, such as unfinished wood, exhibit lambertian reflectance.ĭiffuse (or lambertian) versus specular surfacesĪ smooth surface however reflects light uniformly and creates a very sharp or specular reflection of its environment. Or else: the surface’s luminance is the same regardless of angle of view. Lambertian reflectance means that light falling on a surface is scattered in such a way that the apparent brightness of the surface is the same, regardless of the observer’s angle of view. So it is the reflection of light from an uneven or granular surface, resulting in an incoming light wave being reflected at a number of angles.Ī surface which scatters almost all light in a chaotic, diffuse way is called a “lambertian” surface, such as the red ball on the left.
So what makes a surface look dull, or mirror like? It is the smoothness of that surface.Ī surface which is not very smooth has tiny imperfections which scatter the light in all directions, thus creating a very “diffuse” reflection of its environment. In the real world light does not have a separate “diffuse” or “specular” part. This may sound confusing at first because it has become common in renderers to refer to reflected light as specular (or sharply) reflected light. We see an object because light is reflected from its surface into our eyes. Only the red portion of the spectrum is reflected back. When we perceive an object as red for example, what really happens is that white light falls on a red surface, and all the wavelengths except those that give red light are absorbed by the material. “White light” is a combination of all the colors in the visible light spectrum. The difference in wavelengths (the “tops” of each wave) is what makes the difference between blue, red, gamma rays, x-rays, radio waves etc. This radiation travels in waves of different wavelengths. Visible light is really a very small portion in a range of electromagnetic radiation. To watch all our tutorial videos on Materials click here What is light?