544580397-Lecture-4-Pictorial-Drawing.ppt

EGG

1. Chapter 4
Pictorial Drawing

2. Objectives
Learn how to construct pictorial drawings: Isometric
& Oblique;
Be able to explain the difference between an
axonometric projection and an oblique projection.
Select the best orientation of an object shown in
pictorial;
Sketch pictorials of an object (either oblique or
isometric) given orthographic views of the object or the
actual object;
Pictorial - 3-dimensional representation!!!

3. Examples
Perspective

4. Axonometric projectionAxonometric projection
•axon = axis; metric = measure, in Greek
•Axonometric projection is a parallel projection
technique to create a pictorial drawing of an object
by rotating the object on an axis relative to a
projection or picture plane;

5. Axonometric projection

6. Types of Axonometrics

8. Isometric Projection
& Isometric drawing

9. Orientation of Pictorial Objects

10. Isometrics
•Axes equally separated
(120°)
•H, W, and D
measurements are true
size along iso. Axes
•Circles appear as ellipses
on all surfaces

11. Isometric

12. Rotate 45
about vertical axis
Tilt forward
(35
o
16’)
Isometric Projection
All edges foreshorten
about 0.8 time.

13. Isometric Drawing
Isometric drawing is a drawing drawn on an isometric
axes using full scale.
Isometric projection
(True projection)
Isometric drawing
(Full scale)
Forshorten
Full scale

14. Positions of Isometric Axes
Isometric axes can be arbitrarily positioned to create
different views of a single object.
Regular
isometric
Reverse axis
isometric
Long axis
isometric
View point is looking
down on the top of
the object.
View point is looking
up on the bottom of
the object.
View point is looking
from the right (or left)
of the object.

15. Distance in Isometric Drawing
Isometric line is the line that run parallel to
any of the isometric axes.
Isometric axes
True-length distances are shown along
isometric lines.
Nonisometric lines

16. Producing Isometric drawingProducing Isometric drawing
–Read the orthogonal drawing carefully,
–observe the scale,
–choose the best point where isometric axes meet to reveal as
much detail as possible
–draw an 'isometric box' enclosing the object
–draw in light construction lines
–draw arcs & curves in thick, remove excess..
–line in 30 right lines
–line in 30 left lines
–line in vertical lines to complete the view

17. Selection of Isometric Axes
•Main purpose of isometric view is to provide a pictorial
view which reveals as much detail as possible
•Figure shows different isometric views of the same block

18. 2. Define an isometric axis.
3. Sketching the enclosing box.
4. Estimate the size and relationship of each details
5. Darken all visible lines.
1. Place the object in the position which its shape
and features are clearly seen.
Sketch from an actual object

19. STEPS
1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing box.
4. Add details.
5. Darken visible lines.
Sketch from an actual object

20. 1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing
box.
4. Add details.
NoteIn isometric sketch/drawing), hidden lines are omitted
unless they are absolutely necessary to completely
describe the object.
Sketch from an actual object
STEPS
5. Darken visible lines.

21. Sketch from multi-view drawing
•Read the multi-view drawing given;
•Interpret the meaning of lines/areas in multi-view
drawing;
•Observe scale, dimension, projection angle;
•Try to visualise how the object looks like;
•Start with sketching an isometric box, enclosing the
whole object;
•Locate the lines or surfaces relative to isometric
axis;
•You can label points, lines and surfaces on multi-view
to help visualisation;

22. Constructing an isometric
drawing using the Boxing-
In method
Box in from
the outmost
shape to inside
details.

23. Locating Features
To locate a feature such as the upper block, make
measurements from an existing corner as shown here.

24. Front View
Top View
Side View
Example 1 : Object has only normal surfaces
Side
Front
Top
Regular
W
D
H
H
DW

25. Example 2 : Object has inclined surfaces
W
H

D
y
x Front View
y
x
Nonisometric line

26. Nonisometric line
A
A x
y
x
x
B
B
AB
C
C
C
x
y
Example 3 : Object has inclined surfaces

27. A
A
B
B
C D
E
D
E F
F
x
y
Front View
Regular
C
Example 4

28. Circle & Arc in Isometric
In isometric drawing, a circle appears as an ellipse.
2. Construct an isometric square.
3. Sketch arcs that connect the
tangent points.
Sketching Steps
1. Locate the center of an ellipse.

29. Circle & Arc in Isometric
3. Construct a perpendicular
bisector from each tangent point.
4. Locate the four centers.
5. Draw the arcs with these centers
and tangent to isometric square.
Sketching Steps
Four-center method is usually used when drawn an
isometric ellipse with drawing instrument.
2. Construct an isometric square.
1. Locate the center of an ellipse.

30. Example 5

31. Irregular Curve in Isometric
1. Construct points along the
curve in multiview drawing.
2. Locate these points in the
isometric view.
3. Sketch the connecting lines.
Steps

32. Oblique
Drawing

33. •It is a form of parallel projection where the projectors are parallel to
each other but not perpendicular to the projection plane;
•This form differs from orthographic projection in that, although one
face is imagined parallel to the plane of projection, the projectors make
an angle other than 90
0
–
Commonly 30, 45, or 60 degree.
–Mostly 45 degree is taken

34. Orthographic Projection Oblique projection

35. A
B
C
D
Line
of
sight
Parallel & oblique
to picture plane
Oblique Projection
A
D
C
B

36. Oblique Projection
A
D
C
B
B
C D
A
Oblique drawing angles
30
o
45
o 60
o
Types of Oblique drawing
45
o
45
o
1) Cavalier 2) Cabinet
Full
scale
Half
scale

37. Oblique Drawings
Common oblique angles

38. Oblique Drawing Types
Cavalier ObliqueCabinet ObliqueGeneral Oblique

39. Circles in Oblique
•Drawn true size in
front view
•Drawn as ellipses on
receding planes
•Layout using a
rhombus

40. Constructing an oblique drawing using the
Box-In method

41. D
45
ESTIMATE DEPTH
ESTIMATE LINES
Sketch from actual object

42. Class Exercise: Sketch
from multi-view drawing

43. Sketch from multiview drawing

44. Example of producing Example of producing
isometric drawingisometric drawing

45. Producing Isometric drawingProducing Isometric drawing
•Read multi-view dwg given.
•Observe scale, dimension, proj.
angle
•Try to visualize how the object
looks like.
•Start with sketching, do not
draw straight away.
•Start with sketching an
isometric box, enclosing the
whole object.
•You can label points, lines and
surfaces on multi-view to help
visualization.

46. Practice Exercise
•Complete the
orthographic
views shown
and Sketch an
isometric of
the part.