3-D TERMINOLOGY
2-D
A concept of displaying real-world objects on a flat surface showing only height and width. This system uses only the X and Y axes.
3-D
A way of displaying real-world object in a more natural way by adding depth to the height and width. This system uses the X Y and Z axes.
Boolean operations
Commands that allow you to add, subtract or intersect solid objects in AutoCAD.
Complex surface
Generally a curved surface. Examples: car fender, landscape contour.
Elevation
The difference between an object being at zero on the Z-axis and the height that it is above zero.
Extrude
The extrude command raises the shape of a 2D outline into a 3D solid. For example, a circle would be extruded into a cylinder.
Face
The simplest true 3-D surface.
Facet
A three or four sided polygon that represents a piece (or section) of a 3-D surface.
Hidden line removal
A way of hiding lines that would not be visible if you were viewing the actual object you have drawn in AutoCAD. (Command: HIDE)
Isometric Drawing
A simple way of achieving a '3-D' appearance using 2-D drawing methods.
Plan View
Also known as the top view, a plan view looks directly down the WCS Z-axis to the X-Y axis.
Primitive
A basic solid building block. Examples would be boxes, cones, cylinders.
Region
A 2-D area consisting of lines, arcs, etc.
Rendering
A complex way of adding photo-realistic qualities to a 3-D model you have created.
Shading
A quick way of adding color to a 3-D object you have drawn. (Command:SHADE)
Solid Model
A 3-D model creating using solid 'building blocks'. This is the most accurate way of representing real-world objects in CAD.
Surface Model
A 3-D model defined by surfaces. The surface consists of polygons. (See facets.)
Thickness
A property of lines and other objects that gives them a 3-D like appearance.
UCS
The user co-ordinate system. This is defined by the person drawing to have easier access to portions of a 3-D model.
View
A particular view of the object you have created.
Viewport
A window into your drawing showing a particular view. You can have several viewports on your screen. Different from the viewports used in plotting.
Wire-frame Model
A 3-D shape that is defined by lines and curves. A skeletal representation. Hidden line removal is not possible with this model.
Z-Axis
The third axis that defines the depth.
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