1. Pictorial Drawings and Technical Illustrations
CHAPTER 14
Pictorial Drawings and Technical Illustrations

2. Learning Objectives
Draw three-dimensional objects using 3-D coordinates
Construct objects using isometric, diametric, or trimetric methods
Construct objects using oblique drawing methods

3. Learning Objectives
Draw objects using one-, two-, or three-point perspective
Apply a variety of shading techniques to pictorial drawings
Given an orthographic engineering sketch of a part or assembly, draw the part in pictorial form using proper line contrasts and shading techniques

4. Pictorial Drawings Often accompany 2-D orthographic multiviews
Provide a realistic 3-D view
Help improve visualization
Now created using CADD or illustration programs
ASME Y14.4M, Pictorial Drawing standard

5. Pictorial Drawings Useful for a variety of applications
Clarify basic and complicated engineering designs
Help designers and engineers work out spatial problems
Most often the basis for technical illustrations

6. Pictorial Drawings

7. Uses of Pictorial Drawings
Design
Technical reports
Instruction manuals
Presentations
Assembly
Parts catalogs
Construction
Advertising literature

8. Isometric Projections and Drawings
Equal (iso) measure (metric)
Simplest form of axonometric projection
Single scale for all axes

9. Isometric and Nonisometric Planes

10. Regular Isometric Most common
View the top of the object and the object from either side

11. Reverse Isometric
View the bottom of the object

12. Long-Axis Isometric
Common for long objects

13. Isometric Construction: Box or Coordinate Method
Most common form of isometric construction
Used on objects that have angular or radial features

14. Isometric Construction: Centerline Layout Method
Used on objects with many circles and arcs
Circles in isometric are isometric ellipses

15. Isometric Circles and Arcs

16. Establishing Isometric Intersections

17. Drawing Isometric Sections

18. Drawing Isometric Threads
Equally spaced elliptical arcs
Detailed thread representation

19. Drawing Isometric Spheres

20. Dimetric Pictorial Representation
Form of axonometric projection
Two different scales for measurement
Missing image – go to page 566

21. Trimetric Pictorial Representation
Most involved form of axonometric projection
Three different scales for measurement

22. Exploded Pictorial Drawings
Exploded assembly
Show the relationship of parts in a realistic manner
Commonly used in:
Parts catalogues
Owner's manuals
Assembly instructions

23. Exploded Pictorial Drawings
Isometric drawings most common
Can include centerlines between part and subassembly axes
Can use solid extension lines between non-cylindrical features, parts, and subassemblies
Can include balloons

24. Exploded Pictorial Drawing

25. Oblique Drawing Shows three faces of the object
Useful if one face of an object needs to be shown flat

26. Cavalier Oblique

27. Cabinet Oblique

28. General Oblique

29. Perspective Drawings Most realistic pictorial illustration
Show depth and distortion perceived by the human eye
Objects appear smaller the farther away they are until they vanish at a point on the horizon
One-point or parallel perspective
Two-point or angular perspective
Three-point perspective

30. General Perspective Drawing Concepts

31. One-Point Perspective
Plan view is oriented so the front surface of the object is parallel to the picture plane
Elevation view is placed below and to the right or left of the plan and rests on the ground line
Used most often when drawing interiors of rooms

32. Two-Point Perspective
Two principal planes are at an angle to the picture plane
Two vanishing points provide another dimension to the depth of the perspective
Most popular form of perspective drawing
Exteriors of houses and small buildings
Civil engineering projects
Machine parts (occasionally)

33. Three-Point Perspective
Time consuming to construct
Often occupy a considerable area on the drawing sheet
Used to illustrate objects having great vertical measurements, such as tall buildings

34. Drawing Circles and Curves in Perspective
Circles in perspective typically appear as ellipses
Any circle on surface parallel to the picture plane appears as a circle
Construction using the coordinate method

35. Basic Shading Techniques
Line-contrast shading
Straight-line shading
Block shading
Stipple shading