INTRODUCTION - WHY 3-D?
You may have already figured out why CAD has many advantages
over manual drafting. One big advantage is that once
you've drawn something, you shouldn't have to draw it
again. If you manually drew a house plan, you would have
to draw a front elevation, side elevations, and possibly
a perspective view. With one 3-D CAD model, you can generate
views from any angle either inside or outside the house and animations.
Afterwards, if your client needs something changed, you
can then make the changes once. If you're drawing mechanical
parts, you can generate virtual prototypes or even create
rapid prototypes. In this manner Boeing was able
to design
and prototype the 777 jetliner. This level of
engineering would be impossible without CAD.
Your company may not do a lot of 3D work, but it is still a good skill to have and it's also more fun than 2D.
You'll be learning the 3-D concepts in the following order:
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Isometric Drawings (not true 3D)
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Wire-frame (very basic 3D)
-
Surfaces / Regions (primitive 3D)
-
Solid Objects (advanced 3D)
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You will have a chance to draw the same object different
ways to see the differences between the various methods.
Before entering the exciting world of 3-D, you'll have to learn
some more CAD terminology. This level presumes that you have a good understanding of 2D commands.
3-D CAD 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. |
As computers and software get more sophisticated, working
in 3D becomes more popular. You have more power in desktop
machine today, than was dreamed of when CAD first appeared.
Be prepared that you will likely need to learn 3D at some
point in your career. Once you are comfortable working in
3D, you'll find that you will rarely want to draw in 2D again. Autodesk (the makers of AutoCAD) make other products designed specifically for certain disciplines - Architectural Desktop, Map, 3D Studio Max and more. Depending upon your budget and needs, you may need to look into programs like these. The concepts taught in these lessons will aid you when you work in any 3D program.
Have a look at some AutoCAD renderings in you tube before you start in this new world.
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