solid modelling

Solid Modeling - CAD is the primary uses of solid modeling

Solid modeling is the clear-cut representation of the solid parts of an object and is also known as volume modeling. Other forms of modeling include surface models, which is used extensively in automotive and consumer product design and also in entertainment animation, and wire frame models.
CAD is the primary uses of solid modeling as well as engineering analysis, computer graphics and animation, rapid prototyping, medical testing, product visualization and visualization of scientific research.
The basic theoretical concepts of solid modeling are:
1.Sweeping: An area feature is swept out by moving 2-D sketches along a path to create solid feature. Volumes are either added to the object, which is known as extrusion, or is removed from the material, which is called cutter path. This process is known as sketcher based modeling. This process is used in various manufacturing techniques such as extrusion, milling, lathe, and others.
2.BREP or Boundary Representation: In this process, a solid object is represented by boundary surfaces and then filled to make solid. This process is also referred to as surfacing. It is used in such manufacturing techniques as Injection molding, casting, forging, thermoforming, etc.
3.Parameterized Primitive Instancing: An object is specified through reference to a library of parameterized primitives. A screw for instance is modeled for a library. The model is used for all screw sizes by modifying a set of its parameters.
4.Spatial Occupancy (Voxel): The entire space is subdivided into regular cells, and the object is specified by the set of cells it occupies. Models, which are described this way, lend themselves to Finite difference analysis, which generally occurs once a model has been made. This is part of the automated pre-processing for analysis software.
5.Facet Modeling: This is generally used in reverse engineering pf physical models and is the forming of the outside surface outline of the volume from any triangular planes.
6.Decomposition: This is similar to spatial occupancy, however the cells are not regular, or prefabricated.
7.Constructive Solid Geometry: This is when simple objects are combined using Boolean operators including union, difference, and intersection.
8.Feature Based Modeling: This is complex combinations of objects and operators that are considered a unit that can be modified or duplicated.
9.Parametric Modeling: Elements of features are given labels instead of only fixed numeric dimensions. The relationships between the parameters in the entire model can then be tracked, making changing numeric values of parameters easier.