3D technology has come a long way. 3D computer graphics are different from 2D computer graphics in that a three-dimensional representation of geometric data is stored in the computer for the purposes of performing calculations and rendering 2D images.
A 3D model is the mathematical representation of any three-dimensional object.
3D modeling
3D modeling is the process of developing a mathematical, wire frame representation of any three-dimensional object (either inanimate or living) via specialized software. The product is called a 3D model. 3D models are used for many different functions including animation, design, manufacturing, previsualization, virtual reality, and games.
Modeling is the process of creating 3D objects, whether for animation or otherwise. Simple objects call for simple models, and complicated objects call for a complex of simple models. The tough things are deciding how to represent an object in 3D. Just like a sculptor, you must analyze the object and deconstruct its design to learn how it exists.
3D software uses three types of modeling: NURBS, polygons, and subdivision surfaces. All three types require a process that begins with deciding which modeling method to use.
Modeling processes
Polygonal modeling - Various spots on a xyz grid are mapped out. The dots are connected in a linear fashion to create an outline of the object. The computer then calculates the faces in between these lines. These faces are referred to as polygons.
Polygons are made up of faces. A single polygon face is a flat surface made when three or more points called vertices are connected. The position of each vertex defines the shape and size of face, a triangle. The line that connects one vertex to another is called an edge. Few polygonal faces have four vertices instead of three, creating a square face instead of a triangular one.
NURBS modeling - The spots are mapped out once again, but this time, curved lines are placed in between these spots. How close the line gets to the weights depends on their placement. A group of six weights spaced equidistant from each other will form a circle. But, if you add one more point very close to one of the weights, the circle will become elongated towards the spot of those two points placed closely together. It is based on mathematics that is more complicated than the mathematics for polygons. NURBS modeling requires more processing, this method is typically used for applications in which the rendering is done in advance, such as animation for film or telivision. NURBS modeling excels at creating curved shapes and line, so it is most often used for organic forms such as animals and people,as well as highly detailed cars and the like.
Subdivision Surfaces - It is incorporate the best of polygons and NURBS modeling to give you the ease of polygon creation with the smoothness and organic forms of NURBS geometry. It is usally start as polygonal surfaces. You then use NURBS math to smooth the rough polygon surfaces by subdividing them according to how the model needs to look.
Modeling can be performed by means of a dedicated program (e.g., Maya (software), 3DS Max, Blender, Lightwave), an application component (Shaper, Lofter in 3DS Max) or some scene description language (as in POV-Ray). In some cases, there is no strict distinction between these phases; in such cases modelling is just part of the scene creation process (this is the case, for example, with Caligari trueSpace and Realsoft 3D).
Market for 3D models
There is a large and thriving market for 3D models (as well as 3D-related content, such as textures, scripts, etc.), either as individual models or large collections. Online marketplaces for 3D content allow individual artists to sell content that they have created. Often, the artists' goal is to get additional value out of assets they have previously created for projects. By doing so, artists can earn more money out of their old content, and companies can save money by buying pre-made models instead of paying an employee to create one from scratch. These marketplaces typically split the sale between themselves and the artist that created the asset, often in a roughly 50-50 split. In most cases, the artist retains ownership of the 3d model; the customer only buys the right to use and present the model.
