Unit ii projection of points

Dr.R. GANESAMOORTHY.B.E.,M.E.,Ph.d.
Professor –Mechanical Engineering
Saveetha Engineering College
Tandalam
Chennai.

What is Projections
When you through the light on an object at any angle,
then the image is formed of the object on reference
planes, that image is called Projection.

Objectives- Projection of Points
To draw the projections of a point in the four
quadrants.
To identify the position of the point in different
quadrants.

Define projection of points
The position of a point in engineering drawing is defined
with respect to its distance from the three principle planes
i.e., with respect to the VP, HP, & PP.
VP: The plane in front of observer is the vertical plane.
(VP) or it is also called a Frontal plane.
HP: The plane which is Horizontal and perpendicular to
VP is Horizontal Plane.
Note: The planes HP and VP are called Principal Planes.
Reference Line: The line of intersection of HP and VP is
called reference line, which is denoted by X-Y

Types of views
Front View (FV): The projection on the VP is called
the Front View (FV) or Vertical Projection or front
elevation
Top View (TV): The projection on the HP is called the
Top View (TV) or Horizontal Projection or Plan. or
Elevation.
Side View: The projection on the side from the object
is called the side views.
Side views is classified in to
1.Left side view and (LSV)
2. Right side view(RSV)

Position of points
First quadrant -- Above HP & in front of VP
Second quadrant -- Above HP & behind VP
Third quadrant -- Below HP & behind VP
Fourth quadrant -- Below HP & in front of VP

ORIENTATION OF POINT IN SPACE
(1) In quadrant I (Above H.P & In Front of V.P.)
(2) In quadrant II (Above H.P & Behind V.P.)
(3) In quadrant III (Below H.P & Behind V.P.)
(4) In quadrant IV (Below H.P & In Front of V.P.)
(5) In Plane (Above H.P. & In V.P.)
(6) In Plane (Below H.P. & In V.P.)
(7) In Plane ( In H.P. & In front of V.P.)
(8) In Plane ( In H.P. & Behind V.P.)
(9) In Plane ( In H.P. & V.P.)

Notations of point in views
Following notations should be followed while
naming different views in orthographic
projections.
Object Point
IT’S TOP VIEW a
IT’S FRONT VIEW a’
IT’S SIDE VIEW a’’

Projection of Points in Different Quadrants

Projection of Points in first Quadrant

Projection of Points in II Quadrant

Projection of Points in III Quadrant

Projection of Points in IV Quadrant

1. Point E is in HP and h distance in front of VP
2. Point F is in VP and d distance above HP
3. Point G is in both HP and VP
4. Point H is in HP and d distance behind VP
5. Point J is in VP and h distance below HP

1. Point A is in 15 mm above HP and 20 mm in front
of VP. Draw its projections

2. Point B is lying on HP and 30 mm in front of VP.
Draw its projections

3. Point C which is lying on the VP and 20 mm
above HP. Draw its projections

4. Point Q is in 20 mm below HP and on the VP.
Draw its projections

5. Draw its projections of a Point B which is 10 mm
below HP and 40 mm in front of VP.

6. Mark the projection of the following points on a common
reference line. Take 30 mm distance between the projectors.
1.A 20 mm above HP and 15 mm in front of VP
2.B 20 mm above HP and 30 mm behind VP
3.C 10 mm below HP and 35 mm behind VP
4.D 10 mm below HP and 20 mm in front of VP
5.E 20 mm above HP and in VP 6.F 15 mm below HP and in VP
7.G 8 mm in front of VP and in HP 8.H 18 mm behind VP and in HP

7. Mention the position of the following points with respect to
the planes of Projections. All dimensions are marked in mm
1.Point A 20 mm above HP and 30 mm behind of VP
2.Point B 20 mm below HP and 25 mm in front of VP
3.Point C 25 mm below HP and 30 mm behind VP
4.Point D 30 mm below HP and in VP
5.Point E 25 mm above HP and 20 mm in front of VP

8. A Point C is on HP and 30 mm behind VP. Another point D
is also on HP and 40 mm in front of VP. The distance
between their projectors is 50 mm. join their top views and
determine the inclination of this line with XY line

9.A point P is on HP and 40 mm in front of VP. Another point
Q is also on HP and behind VP. The distance between their
end projectors is 60 mm .Draw its projections if the top view
line joining P and Q makes on angle of 60° with reference line
.and also find the position of Q.

10. Point P is lying in the third quadrant is situated 20 mm below
the below the HP. Its shortest distance from the line of intersection
of planes is 40 mm. Draw its projections and find the distance of
the point from the VP.

11.Point A is 20 mm above HP and in the first quadrant. Its
shortest distance from the reference line XY is 40 mm .Draw the
projections of the point and determine its distance from VP .
Answer: Distance from VP= 40mm

12.Draw the projections of the following points on a
common reference. Take 30 mm distance between the
projectors.
1.Point A 35 mm above HP
and 25 mm in front of VP
2.Point B 40 mm below HP
and 15 mm behind VP
3.Point C 50 mm above HP
and 25 mm behind VP
4.Point D 45 mm below HP
and 25 mm behind VP
5.Point E 30 mm behind VP
and on HP

Unit ii projection of points

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