Important Materials Theory - Photographic Rendering with V-Ray for SketchUp - page 236

Light and material interaction - why
objects in the real world have color
The amazing ability that we have been given as humans to see the world in glorious
color is controlled by two interdependent mechanisms or systems. The first is the
physical interaction of light itself with the solid matter that exists in the world around
us. By this, I mean the walls, chairs, plants, fabrics, and in fact everything solid that
makes up the environment in which we live. This physical interaction is something
that we will explore quite a bit throughout the course of this chapter as it is both ob-
servable and measurable. Being able to gain even just a little understanding on this
particular subject will most definitely impact (in a positive way) our ability to create be-
lievable V-Ray Materials in SketchUp.
The second mechanism is, in essence, you and I ourselves. In a truly amazing way,
our eyes, when combined with the workings of our brains, give us the ability to actu-
ally see (in many ways perceive would probably be a better word), the interaction of
light and matter that is continuously occurring all around us.
Light is where it all starts
When dealing with lighting and rendering inside a 3D application, we are using, in es-
sence, a simplified version of the basic laws of physics that are at work, not just in the
world but in the entire universe around us.
As briefly noted in Chapter 5 , Understanding the Principles of Light Behavior , in the
late 1800s and early 1900s, physicists realized that light was just one tiny part of
a much greater wave spectrum that came to be classified as electromagnetic radi-
ation. In an attempt to more readily understand and explain the workings of these
waves, a classification or measurement system was devised, which assigned both a
wavelength and a frequency to them. Visible light, which occupies only about one-
thousandth of the total spectrum, was found to sit at wavelengths ranging from about
400 (violet) to 700 (red) nanometers.