1. Objective 4.05 Explain computer processes used in computerized 2D/3D modeling

2. Computer Aided Design (CAD)
A computer is a valuable technology tool. A common industrial application for computer systems is in preparing drawings and models.

3. Computer Aided Design (CAD)
CAD refers to the process that uses a computer and drawing software to assist the drafter in preparing mechanical and architectural drawings.

4. Advantages of CAD
Speed
Quality
Ease of modification
Cost reduction

5. Speed
A drafter can produce more drawings in a given amount of time than using traditional drafting methods.

6. Quality
The overall quality of a design is improved by increasing line quality, neatness, legibility, and accuracy.

7. Ease of modification
CAD drawings are stored in memory and can be recalled and modified easily.

8. Cost
All of the previously listed reasons make CAD more cost effective than traditional drafting.

9. The number of dimensions greatly affects the ability to view and display pictorial views of the object.

10. Basic categories of CAD
2D packages store data for the X and Y coordinates only.
2.5D packages also store data points for the X and Y coordinates, but they also provide simplified 3D visualization for objects.
3D programs store X, Y, and Z coordinates of each data. A three dimensional database for each point of an object. The z axis represents the vertical axis in3 D modeling.

11. 3D Systems – Stereo Lithographic Apparatus (SLA)
SLA produces full-size, 3D plastic models directly from CAD drawings.

12. CAD Terminology
Commands- short words which, when entered, causes the computer to perform some function

13. Entity – an object or text item created using CAD software
CAD Terminology
Entity – an object or text item created using CAD software

14. CAD Terminology
Grids-The grid dots assist the drafter in drawing entities. Most programs allow the drafter to adjust the spacing of the dots. This is referred to as grid spacing.

15. CAD Terminology
Snap Grids-When snap grid is on, the cursor jumps from grid point to grid point as it moves across the screen. With snap grid, the cursor can only be positioned at a grid point. Without snap grid, the cursor glides across the screen.

16. CAD Terminology
Rotation-The entity can be rotated by specifying a specific angle of rotation, or it can be rotated by “grabbing on corner of the entity” (called a handle point) and dragging that point around the base point.

17. CAD Terminology
Zoom-allows the drafter to move into a particular part of a drawing. By moving in on the drawing, the drafter can view more details. This function is extremely useful when working with very detailed drawings.

18. Tool bar – a collection of tool buttons grouped together.
CAD Terminology
Tool bar – a collection of tool buttons grouped together.

19. CAD Terminology
Windows- most CAD programs allow the screen to be split into separate windows. Each window is a separate display screen. The windows function is useful when working on very large drawings.

20. Cartesian Coordinates System
A method of graphical point location. All CAD systems use this system as a standard. It allows precise positioning of entities on the drawing surface.

21. Coordinate pair
Represents the position of a point. The first number represents the X coordinate while the second is the Y coordinate.

22. X,Y, Coordinate
The X coordinate is the point's distance from the origin along the X axis. The Y coordinate is the point's distance from the origin along the Y axis. The origin is the intersection of the two axes. The intersection of the X and Y axes creates four quadrants for plotting points.

24. Notice, X and Y points in quadrant I are positive
Notice, X and Y points in quadrant I are positive. In quadrant 2, X is positive and Y is negative. In quadrant 3, both X and Y are negative, while in quadrant 4, X is negative and Y is positive.

26. Absolute Coordinates
Give the position measured from the origin of the drawing. Absolute coordinates refer to precise locations on the Cartesian coordinate grid. For example, coordinates of 4,2 defines a point four units to the right and two units above the origin.

27. Relative Coordinates
Refer to a point or location measured from a previous point. For example, coordinates could be specified for a second point that is at 8,4 from the original point 4,2. To plot this second point, you would move eight units to the right and four units above the point 4,2. The absolute coordinates for this second point would be 12,6.