Talented 3D modelers can simulate the complicated interactions of photons.
The human brain visualizes an object by scooping up photons reflected from its surface. These photons originate from a light source, such as the sun or a table lamp, which emits them at multiple wavelengths in all directions. Some splash on the object being viewed, and are either absorbed or reflected by it. Some of the reflected wavelengths reach the eye, and are translated into full color, three dimensional images. 3D modelers use software tools to simulate this complicated process and produce photo-realistic final images.
3D Light Sources
The sheer number of photons bouncing around in your line of vision would be nearly impossible for even the most powerful computer to calculate in an acceptable amount of time. Instead, smart programmers abstracted certain specific effects of light on a surface into approximate lighting “types.” The most common are ambient light, diffuse light, specular light, and emissive light.
The general average volume of light from all the light sources in the scene. It approximates sun or lamp rays that are bouncing off the walls, for example. When used alone, an ambient light source produces a very flat image.
A soft light cast by a light source coming from one direction. It adds a gradient depth, and when used with an ambient light, will produce a more realistic 3D image.
A hard light cast by a light source coming from one direction gives the viewer an idea of the subject’s reflectivity, simulates highlights, and produces an even more realistic simulation.
Based on the subject’s composition, and specifically the wavelengths of light it absorbs or reflects, an emissive light describes the interference different color wavelengths produce in each other, when combined. For example, a blue balloon absorbs red wavelengths and reflects blue, but under a red light, when there is no blue light to reflect, the balloon appears black.
Using and Placing 3D Light Sources
3D Modelers often use variations of studio or cinematic film lighting techniques to bring out the features and texture of a model, including three-point, silhouette, and edge lighting. But a virtual light map can look quite different from a studio one, as it can often take two or more lights working together to simulate the effect of a practical light. For example, 3D artists generally use more than one light to simulate the effects of sunlight, because sunlight can provide sources of ambient, diffused, and specular light.