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An Overview
Solid modeling, also known as volume modeling, is the representation of the solid parts of an object suitable for computer processing. This representation is accomplished by implementing principles from mathematics, computer science, and engineering that result in theories and computations that define and manipulate the representations including their properties. Solid modeling is used in the research and development of applications as diverse as engineering and product design, computer-aided manufacturing, electronic prototyping, off-line robot programming, and motion planning.
A solid-modeling system utilizes three areas of abstraction:
- User interface: The highest level of abstraction. Means by which user interacts with the system. Provides access to various tools for constructing, modifying, archiving, analyzing, and destroying designs.
- Mathematical and algorithmic infrastructure: Implements the operations available through the user interface. Includes algorithms for constructing the intersection of two objects and determining where and how curved surfaces intersect.
- Substratum of arithmetic and symbolic computations: Lowest level of abstraction. Used by algorithmic infrastructure. Consists of hardware capability for offering integer and floating point arithmetic and programming language capability for offering logical operations expressing computations and viewing storage.
Three types of solid modeling representation are:
- Constructive solid geometry (CSG): A complex shape made up of primitive shapes such as cubes, spheres, cones, and cylinders. Can be represented internally by a binary tree (CSG tree) in which the leaves are the primitive shapes and interior nodes are boolean operations.
- Boundary representations (B-rep): Describes surface of a solid. Could be a data structure composed of vertices, edges, and faces, or a set of equations.
- Spatial decomposition: Modeling three-dimensional shapes. This can be done by utilizing coding the object into voxel data and organizing the data into an octtree or Binary Space Partitioning (BSP) tree data structure.
Solid modeling came about as the result of work done for automatic drafting systems, free-form surface design, and graphics and animation. Automatic drafting systems replaced manual engineering drawing and provided a way to easily modify, archive, and verify the drawings. Free-form surface design led to the field of computer-aided geometric design (CAGD) primarily focusing on methodologies for designing curved surfaces especially in the area of utilizing parametric surfaces that are useful for solid modeling. Graphics and animation has contributed by providing the capability to visualize and construct images from solid representations.
Disclaimer
DPT may not provide some of the services and/or techniques presented in the Knowledge Center. For a full list of services we do offer, please visit our rapid prototyping page.
