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Projection of Points
by Dr. Durga Prasad C B.E, M.Tech, Ph.D (NITK
Surathkal) Assistant Professor Department of
Mechanical Engineering RV Institute of Technology
and Management (RVITM) Bengaluru
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NOTATIONS
FOLLOWING NOTATIONS SHOULD BE FOLLOWED WHILE
NAMEING DIFFERENT VIEWS IN ORTHOGRAPHIC
PROJECTIONS.
OBJECT POINT A
LINE AB
ITS TOP VIEW a
a b
ITS FRONT VIEW a
a b
ITS SIDE VIEW a
a b
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4 QUADRANT THEORY
4
2nd Quadrant
VP
1ST Quad.
2nd Quad.
F.V.
1st Quadrant
Y
Observer
HP
X Y
X
3rdQuadrant
Observer
4th Quad.
3rd Quad.
4th Quadrant
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2nd Quadrant
1st Quadrant
F.V.
Y
X
3rdQuadrant
Observer
4th Quadrant
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Quadrants and Reference Planes
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PROJECTIONS OF A POINT IN THE 4 QUADRANTS
VP
VP
HP
P
P
PF
PT
HP
POINT IN 2nd QUADRANT
PT TOP VIEW PF FRONT VIEW
POINT IN 4th QUADRANT
POINT IN 3rd QUADRANT
PT
HP
HP
HP
VP
VP
HP
PT
PF
P
PF
P
VP
VP
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How you will draw on the sheet
PF
PF
PT
y
y
x
x
PT
POINT IN 2nd QUADRANT
POINT IN 1st QUADRANT
PT
y
x
PT TOP VIEW PF FRONT VIEW
x
y
PT
PF
PF
POINT IN 4th QUADRANT
POINT IN 3rd QUADRANT
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A
a
a
A
Y
a
a
a
X
a
A
Fv above xy, Tv below xy.
Fv above xy, Tv on xy.
Fv on xy, Tv below xy.
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Prob.1. Draw the projections of the following
points on the same ground line, keeping the
projectors 25 mm apart. A, in the H.P. and 20 mm
behind the V.P. B, 40 mm above the H.P. and 25 mm
in front of the V.P C, in the V.P. and 40 mm
above the H.P. D, 25 mm below the H.P. and 25 mm
behind the V.P. E, 15 mm above the H.P. and 50 mm
behind the V.P. F, 40 mm below the H.P. and 25 mm
in front of the V.P. G, in both the H.P. and the
V.P.
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Prob.3. The two points A and B are in the H.P.
The point A is 30 mm in front of the V.P., while
B is behind the V.P. The distance between their
projectors is 75 mm and the line joining their
top views makes an angle of 450 with xy. Find the
distance of the point B from the V.P.
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Prob.4. A point P is 20 mm below H.P. and lies in
the third quadrant. Its shortest distance from xy
is 40 mm. Draw its projections.
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Prob.6. A point 30 mm above xy line is the
plan-view of two points P and Q. The elevation of
P is 45 mm above the H.P. while that of the point
Q is 35 mm below the H.P. Draw the projections of
the points and state their position with
reference to the principal planes and the
quadrant in which they lie.
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