Your 3D world, my 3D world.

In 3D computer graphics, 3D modeling (also known as meshing) is the process of developing a mathematical representation of any three-dimensional surface of object (either inanimate or living) via specialized software. The product is called a 3D model. It can be displayed as a two-dimensional image through a process called 3D rendering. The 3D computermodel can also be physically created using 3D Printing devices.
Today, 3D models are used in a wide variety of fields. The medical industry uses detailed models of organs. The movie industry uses them as characters and objects for animated and real-life motion pictures. The video game industry uses them as assets for computer and video games. The science sector uses them as highly detailed models of chemical compounds. The architecture industry uses them to demonstrate proposed buildings and landscapes. The engineering community uses them as designs of new devices, vehicles and structures as well as a host of other uses.


Scene setup
3Dmodel
 
The geometry in 3D modeling is completely described in 3D space; objects can be viewed from any angle, revealing the lighting from different angles.
Scene setup involves arranging 3D objects, lights, cameras and other entities in a scene which will later be used to produce a still image or an animation.
Lighting is an important aspect of scene setup. As is the case in real-world scene arrangement, lighting is a significant contributing factor to the resulting aesthetic and visual quality of the finished work. As such, it can be a difficult art to master. Lighting effects can contribute greatly to the mood and emotional response effected by a scene, a fact which is well-known to photographers and theatrical lighting technicians.
It is usually desirable to add color or texture to a model’s surface in a user controlled way prior to rendering. Most 3D modeling software allows the user to color the model’s surfaces, and that color is then interpolated across those surfaces during rendering. The most common method of adding color information to a 3D model is by applying a 2D texture image to the model’s surface through a process called texture mapping. Texture images are no different than any other digital image, but during the texture mapping process, special pieces of information (called texture coordinates or UV coordinates) are added to the model that indicate which parts of the texture image map to which parts of the 3D model’s surface. Textures allow 3D models to look significantly more detailed and realistic than they would otherwise. Other effects, beyond texturing and lighting, can be done to 3D models to add to their realism. For example, the surface can be prepared to look rough, smooth, shiny, reflective, irregular, etc.

3D models are often animated for various uses. This can sometimes be done from within the 3D modeler that created them or else exported to another program. If used for animation, this phase usually makes use of a technique called keyframing, which makes complicated movement in the scene possible. With the aid of keyframing, one needs to choose where an object stops or changes its direction of movement, rotation, or scale, between different moments in time. These moments of change are known as keyframes. Often extra data is added to the model to make it easier to animate. For example, some 3D models of humans and animals have entire bone and muscle systems so they will look realistic when they move and can be manipulated via joints and bones, in a process known as skeletal animation.

Advantages of wireframed 3D modeling over exclusively 2D methods include:
Flexibility, ability to change angles or animate images with quicker rendering of the changes;
• Ease of rendering, automatic calculation and rendering photorealistic effects rather than mentally visualizing or estimating;
Accurate photorealism, less chance of human error in misplacing, overdoing, or forgetting to include a visual effect.

3D photorealistic rendering require a steep software learning curve and skills achieving certain photorealistic effects.
(synopsis from Wikipedia page http://en.wikipedia.org/wiki/3D_modeling)

For the best of both worlds, I use a mix of 3D modeling and pixelbased editing the 2D computer-rendered images, mostly with Photoshop.