Line 140423052606 phpapp01, Lecture notes of Abnormal Psychology

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PROJECTIONS OF STRAIGHT LINES

Definition of Straight line:

A straight line is the shortest distance

between two points.

• Top views of two end points of a

straight line, when joined, give the top

view of the straight line.

• Front views of the two end points of a

straight line, when joined, give the front

view of the straight line.

• Both the above projections are straight

lines.

Notatioans used for Straight Line True length of the line : Denoted by Capital letters. e.g. AB=100 mm, means that true length of the line is 100 mm.

Front View Length :

Denoted by small letters. e.g. a’b’=70 mm,

means that Front View Length is 70 mm.

Top View Length :

Denoted by small letters. e.g. ab=80 mm,

means that Top View Length is 80 mm.

Inclination of True Length of Line with H.P. : It is denoted by θ. e.g. Inclination of the line with H.P. (or Ground) is given as 30º means that θ = 30º.

Inclination of Front View Length with XY :

It is denoted by α. e.g. Inclination of the Front

View of the line with XY is given as 50º means

that α = 50º.

Inclination of Top View Length with XY :

It is denoted by β. e.g. Inclination of the Top

View of the line with XY is given as 30º means

that β = 30º.

End Projector Distance:

It is the distance between two projectors passing through end points of F.V. & T.V. measured parallel to XY line.

Inclination of True Length of Line with V.P. : It is denoted by Φ. e.g. Inclination of the line with V.P. is given as 40º means that Φ = 40º.

Line in Different Positions with respect to H.P. & V.P.

CLASS B: Line parallel to (or in) one reference plane & inclined to other two planes

(1) Line parallel to ( or in) V.P. & inclined to H.P.

by .

(2) Line parallel to ( or in) H.P. & inclined to V.P. by .

(3) Line parallel to ( or in) P.P. & inclined to H.P. by  & V.P. by .

Line in Different Positions with respect to H.P. & V.P.

CLASS C: Line inclined to all three reference

planes ( Oblique lines )

Line inclined to H.P. by , to V.P. by  and also inclined to profile plane.

X

Y

a’

b’

H.P.

V.P.

a

b

Class A(1) : Line perpendicular to P.P. & hence

parallel to both the other planes

P.P.

a”, b”

Y 1

H.P.

V.P.

a’

b’

a

b

X

Y

Class A(1) : Line perpendicular to P.P. & hence

parallel to both the other planes

X Y

Profile Plane

a’

b’

a

T.V.=T.L.

F.V.=T.L.

Y 1

Y 1

Data given :-

(1) T.L. = 50mm

(2)Point A

20 below H.P. 30mm Behind V.P.

(3) Line is perpendicular

to P.P.

(4) Line is 10mm left of

P.P.

Scale :- 1:

Exercise 1 :- A Line AB, 50mm long is perpendicular to the

profile plane. The end A is 20mm below H.P. , 30mm

behind V.P. & 10mm to the left of P.P. Draw the

projections of straight line AB (i.e. Front View & Top

View).

b..

V.P.

H.P.

Y

X

A

B

b

a

a’, b’.

Y

X

Class A(2):Line perpendicular to V.P. & (hence)

parallel to both the other Planes

(i.e. H.P. & P.P.)

V.P.

H.P.

a’, b’

X Y

a

b

T.V.

F.V.

.

Class A(2):Line perpendicular to V.P. & (hence)

parallel to both the other Planes

50 a

b

c

a’,b’,c’

X^ Y

Exercise 2 :- A Line ABC, 80mm long is perpendicular

to V.P & 50mm below H.P. Point B, 20mm from A is on

V.P. A is in 4th^ quadrant. Draw the projections of line

ABC.

Data given :-

(1) T.L. = 80mm

(3) Point B is in V.P.

- Line is perpendicular to V.P.

(4) Line is 50mm below H.P.

Scale :- 1:

(2) AB = 20, BC = 60

- Point A is in 4th^ quadrant

a,b

. H.P.

Class A(3):Line perpendicular to H.P. & (hence)

parallel to both the other Planes

V.P.

a’

b’

Y

X

X Y

a’

b’

a, b

.

H.P.

V.P.

Class A(3):Line perpendicular to H.P. & (hence)

parallel to both the other Planes