3D modeling

In 3D computer graphics, 3D modeling is the process of developing a mathematical, wireframe representation of any three-dimensional 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 or used in a computer simulation of physical phenomena. The model can also be physically created using 3D Printing devices.

Models may be created automatically or manually. The manual modeling process of preparing geometric data for 3D computer graphics is similar to plastic arts such as sculpting.

Models

3D models, the product of modeling procedures, are often created with special software applications called 3D modelers. Being a collection of data (points and other information), 3D models can be created by hand, algorithmically (procedural modeling), or scanned. Though they most often exist virtually (on a computer or a file on disk), even a description of such a model on paper can be considered a 3D model.

A 3D model of a Mangalore from the film The Fifth Element in the 3D modeler LightWave, shown in various manners and from different perspectives

3D models are widely used anywhere 3D graphics are used. Actually, their use predates the widespread use of 3D graphics on personal computers. Many computer games used pre-rendered images of 3D models as sprites before computers could render them in real-time.

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. In recent decades the earth science community has started to construct 3D geological models as a standard practice.

A model is not technically a graphic until it is visually displayed. Due to 3D printing, 3D models are not confined to virtual space.

[edit] Modeling processes

A fully textured and lit rendering of a 3d model.

There are three popularly used means by which to represent a model:

• Polygonal modeling - Various vertices on an xyz grid are mapped out. The vertices are connected in a linear fashion to form a polygonal mesh. Used for example by Maya 3d.
• NURBS modeling - Curves are formed by defining control points and attaching a "weight" to each one. The curve follows (but does not necessarily interpolate) the points. Increasing the weight for a point will pull the curve closer to that point. NURBS are particularly suitable for organic modelling. Used for example by Rhino3d.
• Splines&Patches modeling - Curves which define the surface directly (Splines) used for example by Hash Animation:Master.

The modeling stage consists of shaping individual objects that are later used in the scene. There are a number of modeling techniques, including:

• constructive solid geometry
• implicit surfaces
• subdivision surfaces

Modeling can be performed by means of a dedicated program (e.g., Maya, 3DS Max, Blender, Lightwave, Modo) or 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).

Complex materials such as blowing sand, clouds, and liquid sprays are modeled with particle systems, and are a mass of 3D coordinates which have either points, polygons, texture splats, or sprites assign to them.