After completing this chapter you will be able to: Understand the terminology used in 3-D modeling, define the most popular types of 3-D modeling systems, apply Boolean operations to 3-D objects, understand the role planning plays in building a constraint-based model. | Solid Modeling – Primitives and Boolean Operations Need to start modeling right away Will talk about background and theoretical issues later Solid Primitives Primitives are simple solid objects created directly in a CAD system Examples include: box, sphere, cylinder, cone, wedge, torus Model Building in AutoCAD Length - in x axis direction Width - in y axis direction Height - in z axis direction Length, width and height can be positive or negative A positive dimension indicates movement in direction of positive axis A negative dimension indicates movement in opposite, or negative direction In AutoCAD, the following dimensions are associated with the three coordinate axes: Solid Composites Primitives combined using Boolean operations to create solid composites Boolean operations used in solid modeling are: Union Intersection Subtraction Union Union means set of all elements belonging to either A or B A È B Union of two or more solids creates a composite solid composed of combined volumes of these solids In set theory, the union of two sets, A and B, is represented pictorially as: Parts common to A and to B are only counted once Intersection Set of all elements belonging to both A and B A Ç B Intersection of two or more solids creates a composite solid composed of volume common to original solids Intersection of two sets, A and B: Subtraction 1 Set of all elements belonging to A but not B A – B Subtraction of two solids creates a composite solid composed of volume of first solid minus common volume shared with second solid Subtraction of two sets, A and B: Subtraction 2 Alternatively, B - A is represented pictorially as: Solid Modeling – Primitives and Boolean Operations . | Solid Modeling – Primitives and Boolean Operations Need to start modeling right away Will talk about background and theoretical issues later Solid Primitives Primitives are simple solid objects created directly in a CAD system Examples include: box, sphere, cylinder, cone, wedge, torus Model Building in AutoCAD Length - in x axis direction Width - in y axis direction Height - in z axis direction Length, width and height can be positive or negative A positive dimension indicates movement in direction of positive axis A negative dimension indicates movement in opposite, or negative direction In AutoCAD, the following dimensions are associated with the three coordinate axes: Solid Composites Primitives combined using Boolean operations to create solid composites Boolean operations used in solid modeling are: Union Intersection Subtraction Union Union means set of all elements belonging to either A or B A È B Union of two or more solids creates a composite solid composed of combined volumes of these solids In set theory, the union of two sets, A and B, is represented pictorially as: Parts common to A and to B are only counted once Intersection Set of all elements belonging to both A and B A Ç B Intersection of two or more solids creates a composite solid composed of volume common to original solids Intersection of two sets, A and B: Subtraction 1 Set of all elements belonging to A but not B A – B Subtraction of two solids creates a composite solid composed of volume of first solid minus common volume shared with second solid Subtraction of two sets, A and B: Subtraction 2 Alternatively, B - A is represented pictorially as: Solid Modeling – Primitives and Boolean Operations Chega!
