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4.4 VIEWPOINT

This point represents the position in 3D space as we view the model while looking toward the
origin (0,0,0). Viewpoint coordinate values are relative to the world coordinate system. The

conventions for defining standard views differ between architectural (AEC) and mechanical design.

In AEC design, the perpendicular view of the XY plane is the top or plan view; in mechanical
design, the perpendicular view of the XY plane is the front view.

4.5 UCS

There are two coordinate systems: a fixed system called the world coordinate system (WCS) and a

movable system called the user coordinate system (UCS). By default, these two systems are

coincident in a new drawing.
Normally in 2D views, the WCS X axis is horizontal and the Y axis is vertical. The WCS origin is

where the X and Y axes intersect (0,0). All objects in a drawing file are defined by their WCS
coordinates. However, it is usually more convenient to create and edit objects based on the

movable UCS.

4.6 WORKSPACE

A set of menus, toolbars and dockable windows (such as the Properties palette, Design Center, and

the Tool palettes window) that are grouped and organized so that you can work in a custom, task-

oriented drawing environment.

4.7 GEOMETRIC MODELING TECHNIQUES

Geometric models that once were more than adequate for drafting purposes are not acceptable for

engineering applications. A basic requirement, therefore, is that a geometric model should be an
unambiguous representation of its corresponding object. That is to say, the model should be unique

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