Copyright Goodheart-Willcox Co., Inc. Chapter 3 Viewing and Displaying Three-Dimensional Models 55 PROFESSIONAL TIP PROFESSIONAL TIP The quickest method of dynamically rotating a 3D model is achieved by using the mouse wheel button. Simply press and hold the [Shift] key while pressing down and holding the mouse wheel. Now move the mouse in any direction and the view rotates accordingly. This is a transparent function that executes the 3DORBIT command and can be used at any time. Since it is transparent, it can even be used while you are in the middle of a command. This is an excellent technique to use because it does not require selecting another tool or executing a command. Projection The view displayed in the drawing window can be in one of two projections. The projection refers to how lines are applied to the viewing plane. In a pictorial view, lines in a perspective projection appear to converge as they recede into the background. The points at which the lines converge are called vanishing points. In 2D drafting, it is common to represent an object in pictorial as a one- or two-point perspective, espe- cially in architectural drafting. In a parallel projection, lines remain parallel as they recede. This is how an orthographic or axonometric (isometric, dimetric, or trimetric) view is created. To quickly change the projection using the viewport controls, pick Parallel or Perspective from the View Controls fl yout. To change the projection using the view cube, right-click on the view cube to display the shortcut menu, or pick the shortcut menu button at the lower-right of the view cube. Refer to Figure 3-5. Three display options are given: • Parallel. Displays the model as a parallel projection. This creates an ortho- graphic or axonometric view. • Perspective. Displays the model in the more realistic, perspective projection. Lines recede into the background toward invisible vanishing points. Pick Pick Orientation of UCS View is relative to the UCS A B Figure 3-6. A—When one of the corners of the cube is selected, a standard isometric view is displayed. B—Selecting one of the edges of the cube produces the same rotation in the XY plane as an isometric view, but a zero elevation view in the Z plane.