It may be all well and good creating a fantastic looking model, but without proper lighting, a multitude of sins can stick out like a sore thumb! I thought it would be interesting to research popular tools and methods used to give subtle light to environments for a more realistic look, harsher lights, and so forth.
To begin, Radiosity, an illumination algorithm, is an addition to many of the render methods that exist in 3D modelling and animation. Unlike various other methods (Mental Ray and Raytrace are another couple of lighting algorithms), Radiosity is slightly unconventional in some respects as it doesn't focus on the usual method of "reflection of light ray>directly to an object>eye". It is based around the more natural idea that a ray from a light source will reflect on many objects and then back to the eye, thus allowing a mix of colours depending on the colours of the light source and the objects. This is particularly useful when lighting interior environments as walls and other multiple rooms may not be in the direct path of a light source, so it will heavily rely on the reflections from other objects. Although from Wikipedia, here is an image perfectly depicting the use of Radiosity with a comparison against another more unnatural lighting technique. Radiosity uses GI (Global Illumination) which is a way of following natural light behaviour i.e. casting rays by following realistic rules. Many renderers use GI.
Many people's opinions on internet forums seem to sway more towards Mental Ray as the choice for rendering and lighting as apparently it is more predictable. Some have argued that it is all a matter of personal preference and that the only way to truly decide on the best renderer is to try them all and do tests. I personally think that it is important to test out as many methods as you can in order to have a valuable opinion on what works for you. As a student, we have only been given Mental Ray as the renderer of choice - possibly because it is reliable - and I do wish to play with many more to get an idea of what they all do.
Mental Ray has a feature called caustics which allows a ray of light to say for instance, shine onto a wall in a room and then reflect the light onto other surfaces. "A Look At Caustics" by Jeremy Birn - http://www.3drender.com/light/caustics.html - is a very helpful guide on how caustics work in animation. Below is an image from his article showing a side by side comparison on how a rendered image looks with and without caustics to enhance lighting properties.
A Raytraced image (Left) and Raytrace enhanced with caustics (Right)
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