TAPESTRY: The Art of Representation and Abstraction
Data Types - Solid
What's it all about?
All of the real objects with which we are familiar are solids, even thin pieces of paper. They have insides and outsides, from which we can derive volumes, areas, centers of mass, etc.
Primitives
Several different systems have been developed to represent solids. Some, called Constructive Solid Geometry (CSG) modelers, focus on the process by which the solid form might be carved from a large block of material. These models are often used to control digital equipment to actually manufacture the shape, or a mold for the shape. Primitives are usually a combination of Platonic solids (spheres, cylinders, blocks, etc.) and Boolean operations used to combine the basic shapes. Since these operations work on pairs of objects, complex objects are built up from numerous operations, all of which are stored and processed as a CSG tree.Others, called polyhedral or Euler modelers, extend the basic boundary representation by applying a set of tests and operations known as Euler Operators. These operations preserve the "inside" vs. "outside" distinction, making it possible to perform Boolean operations on the resulting geometry.
Attributes
Surface attributes are essentially identical to those of boundary modelers, but solid models may also include material attributes such as density, allowing calculations of weight.Examples
form•Z, Microstation, Solidworks, Rhino solids.
Last updated: April, 2014
