Introduction to CAD

Computer-aided design (CAD) is:using a computer to create virtual objects or scenes.

Introduction to CAD

CAD programs are 3D Modeling programs for designing or running virtual tests on objects meant to be created in real life. You can learn CAD concepts in most 3D modeling programs.

3D Modeling programs without the word “CAD” in the title are usually able to create visualizations of objects that cannot be manufactured in real life.

Computer-aided design (CAD)and 3D Modeling:

is there a difference?

3D Modeling Tools

Primitive-based Modeling

Using Primitives (simple objects, also called Meshes) to create other objects

Images from Caligari® trueSpace® [sic] (Freeware)

Donut (or Torus)

Cone

Sphere

Cylinder

Square (or Plane)

Cube

3D Modeling Tools

Primitive-based Modeling

• Can include Boolean operations:

Subtracting one object from another, such as subtracting a box to create a door on a house.

3D Modeling Tools

Primitive-based Modeling• Particles may be considered Primitives, and particle emitters can

either emit small 3D objects or small 2D images or animations overlaid onto otherwise invisible rectangles.

Eduardcaliman4d. “Trapcode Particular 2 - Particle Trail [eduard caliman].” <http://www.youtube.com/watch?v=P47abggOdhg> accessed 2010-09-08

3D Modeling Tools

Not all objects are made from simple objects. Some are made from curves.

3D Modeling Tools

Spline-based ModelingCreating 2D Splines then using operations to transform them into 3D objects.

3D Modeling Tools

Spline-based Modeling• Based on Spline Curves• A Spline is a Curve with control points and that

generates other points in between, resulting in a smooth curve.

– Béziers are handles which control the direction and tightness of the curve.– Splines can have either:

symmetrical, asymetrical, or automatic Béziers.

3D Modeling Tools

Lathe Extrude(3 extrusionoperations

are pictured)

Loft

Spline-based Modeling

• There are several operations that use splines to generate 3D Objects. The most common are shown below:

+

= water slide

3D Modeling Tools

In CAD programs, true circles are usually used instead of splines, in order to make the object easier to recreate using real life tools.