1. Introduction to PROJECTION

2. PROJECTION is defined as an image or a drawing of an object made on a plane.

4. To convey the external as well as internal features of objects in terms of shape and size.

5. Principles of Projection.
All drawings used in the field of engineering are based on the
Principles of Projection.

7. Pictorial View to reveal all three directions of space in one picture.
PROJECTION is defined as an image or a drawing of an object made on a plane.
Pictorial View to reveal all three directions of space in one picture.

8. It is capable of conveying the external as well as internal features of objects in terms of shape and size.

9. PROJECTION METHOD
Light

10. Line of sight is an imaginary ray between an observer’s eye and an object.
There are 2 types of LOS :
parallel
and
diverging
Parallel projection
Perspective projection
Line of sight
Line of sight

11. 1) It is difficult to create.
Perspective projection is not used by engineer for manufacturing of parts, because…
1) It is difficult to create.
2) It does not reveal exact shape and size.
Width is distorted

12. Plane of projection is an imaginary flat plane which
the image is created.
The image is produced by connecting the points where
the LOS pierce the projection plane.
Parallel projection
Plane of projection

13. PROJECTION THEORY
The projection theory is used to graphically represent
3-D objects on 2-D media (paper, computer screen).
The projection theory is based on two variables:
1) Line of sight
2) Plane of projection (image plane or picture plane)

14. PROJECTION METHOD
Perspective
Parallel
Oblique
Orthographic

15. Orthographic Projection

16. MEANING Orthographic projection is a parallel projection technique
in which the parallel lines of sight are perpendicular to the
projection plane 1 2 5 3 4

17. ORTHOGRAPHIC VIEW Two dimensions of an object is shown.
Orthographic view depends on relative position of the object to the line of sight.
Rotate
Two dimensions of an
object is shown.
Tilt
More than one view is needed
to represent the object.
Multiview drawing
Three dimensions of an object is shown.
Axonometric drawing

18. OBJECT REPRESENTATION
Orthographic projection technique can produce….
Axonometric projection ~ that shows all three dimensions of an object in one view.
Multiview projection ~ that each view show an object in two dimensions.
Both drawing types are used in technical drawing for communication.

19. PROJECTION METHOD Perspective Parallel Oblique Orthographic
Axonometric
Multiview

20. Perspective / Axonometric / Oblique Projection

21. MULTIVIEW PROJECTION Three principle dimensions of an object …
… can be presented only
two in each view.
Depth
Height
Adjacent view(s)
is needed to fulfill the size
description.
Depth
Width
Height
Width
Depth

22. TO OBTAIN MULTIVIEW REPRESENTATION OF AN OBJECT
Revolve the object with respect
to observer.
The observer move around the
object.

23. REVOLVE THE OBJECT
Top view
Front view
Right side view

24. Top view
Front view
Right side view

25. Top view
Front view
Right side view

26. THE GLASS BOX CONCEPT
Rear view
Left side view
Bottom view

27. History
Depth
Height
Width

31. 2nd Quadrant
F.V.
1st Quadrant Y X
3rdQuadrant
Observer
4th Quadrant

34. POINT A IN 2ND QUADRANT POINT A IN 1ST QUADRANT HP VP VP HP a’ A A a’
OBSERVER
OBSERVER a a HP VP HP VP
OBSERVER
OBSERVER a a’ A a’
POINT A IN
3RD QUADRANT A
POINT A IN
4TH QUADRANT

35. Orthographic Pattern
For Tv
(Pictorial Presentation)
V.P. X Y
H.P.
V.P. a’ b’
a b Fv Tv
Note:
FV is a vertical line
Showing True Length
&
TV is a point. a’ b’ B A 1. FV
A Line
perpendicular
to Hp
&
// to Vp X Y
For Fv
a (b) TV
Orthographic Pattern
(Pictorial Presentation) X Y
V.P.
Note:
Fv & Tv both are
// to xy
&
both show T. L. X Y
H.P.
V.P. a b a’ b’ Fv Tv
For Tv 2. b’ a’
A Line
// to Hp
&
// to Vp
F.V. A B
For Fv b a
T.V.

36. (Pictorial presentation)X Y
V.P. X Y
H.P.
V.P.
F.V.
T.V. a b a’ b’ 
Fv inclined to xy
Tv parallel to xy. 3. b’ a’
F.V.
A Line inclined to Hp
and
parallel to Vp
(Pictorial presentation) A B   b a
T.V.
Orthographic Projections
V.P.
Tv inclined to xy
Fv parallel to xy. X Y
H.P.
V.P. Ø a b a’ b’ Tv Fv 4.
A Line inclined to Vp
and
parallel to Hp
(Pictorial presentation) a’ b’
F.V. Ø B A Ø a b
T.V.

37. 3.
TRACE X Y
V.P. b’ a’
F.V. A B   b a
T.V.

38. TRACE 4.
V.P. a’ b’ Ø B A Ø a b

39. line inclined to HP II to VP.wmv line inclined to VP II to HP.wmvX Y a b1 a’
b1’  X Y φ a b2 a’
b2’ X Y φ a b2
b2’ b1 a’
b1’  P P Q Q R S R S
ab1= is length of TV
PQ = locus of b’
ab’2= is length of FV
RS = locus of b
line inclined to HP II to VP.wmv
line inclined to VP II to HP.wmv
From II to VP to inclined to VP.wmv
From II to HP to inclined to HP.wmv

40. PICTORIAL PRESENTATION
Projection of Planes
SURFACE II TO HP & ┴ TO VP
PICTORIAL PRESENTATION
For T.V.
FV-1 D C A B
For F.V.
T V-1
TV-True Shape
FV- Line // to xy

41. PICTORIAL PRESENTATION
Projection of Planes
SURFACE II TO VP & ┴ TO HP
PICTORIAL PRESENTATION
For T.V.
FV-1
For F.V.
T V-1
TV-True Shape
FV- Line // to xy

42. Projection of Planes SURFACE ┴ TO HP & ┴ TO VP
ORTHOGRAPHIC PRESENTATION
PICTORIAL PRESENTATION
For T.V. SV FV FV A B D
For SV . C
For F.V.
T V
T V
TV-Line ┴ to xy
FV- Line ┴ to xy