1. Visualization and Graphics Introduction
Drafting, Sketching & Dimensioning

2. Objectives Understanding graphics as a communication tool
Technical sketching
Freehand
Instrument
Computer
Projections
Orthographic
Pictorial
Today’s objectives are:
Sketching and Isometric Pictorials - At the end of the session, students should be able to:
Infer that technical drawings are effective tools for communication of technical ideas
Differentiate between multi-view and isometric drawings
Develop isometric sketches of tangible objects on isometric grid sheet
Just doing a brief overview of first two topics. We will spend most of the time on Introduction to Projections in particular isometric projection.

3. Visualization
Visualization is often used as a mode of communication between engineers
Sketches, tables, graphs, computer generated drawings, blueprints are various ways in which engineers communicate via visual mediums

4. How Would You Describe This?
In teams of two, describe using only words
How effective is this approach?
Instructor:
This is an in-class interactive exercise(active learning). Allow students about 5 minutes to discuss with partner and then ask random students to put in words their description. Then ask the class the question shown on the slide.

5. Three Basic Types of Technical Drawings
Freehand sketches
Instrument drawings
Computer drawings
In this class we will focus primarily on Freehand Sketching and Computer Based drawing
CAD programs have replaced much of Instrument drawing process.
Technical sketches are how engineers “think” and communicate with each other. All the way from napkin session at lunch to formal computer based solid models and flow charts.

6. Introduction to Projections
Present 3-D objects with 2-D media
Two Basic Categories
Orthographic Pictorial
Definitions:
Projection: the process or technique of reproducing a spatial (3-D) object upon a plane or curved (2-D) surface
Orthographic sketches present the object in a series of projections, each one showing only two of the object’s three dimensions.
Pictorial sketches present the object in a single view with all three dimensions represented
Discuss the trade-offs in using any type of projection; some are more realistic, some are easier to draw, and some are easier to interpret by non-technical people

7. Projections: Four Basic Types
Note: Isometric is a special case of Axonometric
Orthographic Projections
Axonometric
Course emphasizes on multi-view (orthographic) and isometric (one type of axonometric pictorial) projections only
Multiview projections are a collection of 2-D views
Pictorials are 3-D
Pictorials
Oblique
Perspective

8. Types of Axonometrics

9. Pictorial Drawings Shows an object like you would see in a photograph
Give a three dimensional view of a room or structure
Three common types
Isometric (Axonometric)
Oblique
Perspective

10. Pictorial Sketch of Kitchen

11. Review Questions 1-2

12. Isometric Drawings The most common pictorials
Constructed with the two faces 30 degrees above the horizontal
The axes are 120 degrees between each axis
Lines that are horizontal are drawn at 30 degrees
Vertical lines remain vertical

13. Isometric Projection CUBE
One type of axonometric pictorial (3-D) projection
‘Iso-’ means ‘equal
‘metric projection’ means ‘a projection to a scaled measure’
The three dimensions are not only shown in one view, but also the dimensions can be scaled from this drawing
START WITH A CUBE
All of the normal drawing planes (top, front, side) are equally foreshortened or tilted, and all of the major axes (X, Y, Z) are at equal rotations from each other (120 degrees apart), as in the illustration above.
And, because all of the major planes are equally foreshortened, all of the measurements in these planes are equal as well as shown above. This means that the same measuring scale may be used in drawing both the width, height, and depth of objects.
Isometric means equal measure
All planes are equally or proportionately shortened and tilted
All the major axes (X, Y, Z) are 120 degrees apart

14. Making an Isometric Sketch
Defining Axis
30o
60o
Isometric Axis
Derive the axes from a vertex of the cube

15. Isometric of a Cube

16. Isometric Dimensioning
Dimension lines are parallel to the isometric axes
Extension lines are extended in line with these axes

17. Oblique Drawings
The front view is draw like it would be using orthographic projection
The front view shows all features with true shape and size
The top and side view are then projected back from the front view
Views can be at any angle
15, 30 or 45 degrees are common

18. Oblique Drawing

19. Oblique Drawings Continued
Useful when the front contains more details and features than the side view
A mental image can be created more quickly than with orthographic alone
Two types of oblique drawings
cavalier
cabinet

20. Review Questions 3-5

21. Cavalier Oblique The entire drawing uses the same scale
Sometimes creates a distorted appearance

22. Which is the cube ?

23. Were you right?

24. Cavalier Oblique Front view true size
Receding Axis Angle (Normally 30°, 45° or 60°) is Variable
Depth dimension (receding axis) true size

25. Cabinet Oblique Front view true size
Receding Axis Angle (Normally 30°, 45° or 60°) is Variable
Depth dimension (receding axis) half size

26. Cavalier Oblique Drawing

27. Cabinet Oblique Measurements on the receding axes are reduced by half
More visually realistic representation
Often used for drawing cabinets

28. Cabinet Oblique Drawing

29. Side by Side Comparison
Cavalier Oblique
Cabinet Oblique

30. Review Questions 6-8

31. Perspective Drawings The most realistic of all pictorial drawings
Receding lines in the drawing “meet” at a vanishing point instead of being parallel
Eliminates distortion at the back part of pictorial drawings
Two types
parallel (one-point) perspective
angular (two point) perspective

32. Perspective Drawing

33. Parallel Perspective (One Point)
One face of the object is shown as the front view
Lines parallel to the front view remain parallel
Lines that are perpendicular to the front view converge at a SINGLE VANISHING POINT

34. Angular Perspective (Two-Point)
Similar to isometric drawings
One edge of the object is place in front
The two faces that meet at this edge recede to DIFFERENT VANISHING POINTS
All lines parallel to each face go to the different vanishing points

35. Angular Perspective Drawing

36. Types of Perspectives

37. Horizon Below Object

38. Exploded Pictorial Drawings
Used to show relative position of parts or construction details
Used to clarify assembly sequence
Common in appliance and cabinetry service manuals

39. Exploded Pictorial Drawing