University Institute of Engineering

Academic Unit-1-4
Bachelor of Engineering
Computer Graphics using CAD Lab. (21MEP-102)
Experiment No. 4 & 5
Prepared By: Paras Khullar

PROJECTION OF POINTS DISCOVER . LEARN . EMPOWER

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 PROJECTION
OF POINTS
Course Outcome
CO Title Level
Number After completion of the course the students may be able to:

CO1 Sketch the different conventions and representations of Remember

engineering graphics on AutoCAD software. & Understand
CO2 Explain the use of engineering drawing, compare and Understand Image Source: http://cadmasters.guru/2d-to-3d-conversions/
predict the geometrical details of common engineering  
objects.
CO3 Classify, examine and draw the dimensioned figures Understand
expressing information about the shape and size of physical
objects
CO4 Identify and express the geometrical features of a product Understand
on AutoCAD software.   Will be covered in this
CO5 Understand lecture
Draw orthographic views of computer components. 2
 
 COURSE
OBJECTIVES
Students may be able to
• Understand the concept of orthographic projections
• Differentiate between different views Image Source: https://img-a.udemycdn.com/course/750x422/1925256_3592_5.jpg
• Locate a point in orthographic projections
• Understand the placement of a point in different
quadrants
• Label the projections in different planes
• Understand the concept of reference planes

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 Projection

• View of an object that is visible to the observer from a particular

direction
• Projection observed from
o the top is called as Top View
o the front is called as Front View
o the Side is called a Side View
• These types of projections are known as Orthographic Projections as
the all the views are observed at and angle of 90° to each other

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 Concept of Projections
• To draw projections of any point, following information is must
1. Object
2. Observer
3. Plane of Projection

Fig. 3.1: Position of Object, Observer & Plane of Projection

Image Source:
http://ednotebook.hostgator.co.in/theory-of-projection 5
 Orthographic Projections

• Type of technical drawing in which different views of an object are

projected on different reference planes
• Views are observed perpendicular to the different reference planes
• All the views are observed at right angles to each other.
• For example front view, top view and side views are drawn by
observing perpendicular to each other.

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 Planes
There are two types
of planes
1. Principal Planes:
• Horizontal Plane
• Vertical Plane
2. Auxiliary Planes: Fig. 3.2: Principal Planes

•Auxiliary Inclined
Plane
•Auxiliary Vertical
Plane
•Profile Plane
Image Source: www.slideshare.net 7
Fig. 3.3: Auxiliary Planes
 Quadrant System and Reference Planes
• Observer is assumed to view the object from right side

VP
2nd Quad. 1ST Quad.

Y
Observer

X Y HP
X

3rd Quad. 4th Quad.

Animation Source: www.slideshare.net 8

 Quadrant System and Reference Planes
• VP stands for Vertical Plane and HP stands for Horizontal Plane
• For every quadrant, HP rotates by 90° clockwise direction and VP
remains stationary
• Front View is always drawn on VP, also known as Vertical
Projection
• Top View is always drawn on HP, also known as Horizontal
Projection

Fig. 3.4: Quadrant System

Image Source: www.educationportals.net 9
 Notations
• Every projection has a particular notation
• Every object (point, line, plane, etc.) is always represented by upper
case letters. For example:
• A for a point
• AB for a line
• ABCD for a plane
• The projections for the different objects are represented as the same
alphabet of its name in the lowercase
S.No Type of Drawn on Notation for object Line AB Plane ABCD
Projection Point A

1 Top View HP a ab abcd

2 Front View VP a’ a’b’ a’b’c’d’
3 Side View PP a” a”b” a”b”c”d”
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Table 3.1: Notations for the Objects
Locations of the Point w.r.t. Reference Planes
• As the position of the observer is fixed, the location of the point is
determined as follows:
• If point A
o lies above HP and in front of VP the point lies in 1st quadrant
o lies above HP and behind VP, the point lies in 2nd quadrant
o lies below HP and behind VP, the point lies in 3rd quadrant
o lies below HP and in front of VP, the point lies in the 4th quadrant

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Locations of the Point w.r.t. Reference Planes
• First quadrant: V.P is above X-Y line and H.P is below X-Y line
• Second quadrant: V.P and H.P both are above X-Y line
• Third quadrant: H.P is above X-Y line and V.P is below X-Y line
• Fourth quadrant: V.P and H.P both are below X-Y line

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Locations of the Point w.r.t. Reference
Planes
VP POINT A IN
POINT A IN 1 QUADRANT
ST
2ND QUADRANT VP a’
A A
a’
a
HP OBSERVER

HP OBSERVER

HP OBSERVER HP OBSERVER

POINT A IN
POINT A IN 4TH QUADRANT
a’ a
3RD QUADRANT
A
a’ A
Animation Source: www.slideshare.net 13
VP
VP
 Projections of Point in 1st quadrant
POINT A ABOVE HP POINT A ABOVE HP POINT A IN HP
& INFRONT OF VP & IN VP & INFRONT OF VP
For TV
For TV

PICTORIAL PICTORIAL For TV

PRESENTATION A PRESENTATION
a’ a’
For
A F V
For Y Y
Y F a’
V a
a
X a X X A For
F V

ORTHOGRAPHIC PRESENTATIONS
FV above XY, OF ALL ABOVE CASES. FV on XY,
TV below XY.
TV below XY.
VP FV above XY,
VP
TV on XY.
a’ VP

X Y a’ a’
X Y

a X a Y
a
HP
HP
Animation Source: www.slideshare.net 14
HP
 Applications
• Projection of points are applicable for fitting of bulbs in the buildings.
• These are also used for the installation of towers and poles.

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 Summary

• In this PPT we have studied the concept of projections

• The concept of object observer and plane of projection
• Quadrant system and its rules
• Various principal planes
• Views of orthographic projections
• Nomenclature of various views of orthographic projections

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 Assessment Pattern
Final Weightage in
Sr. Weightage of actual Internal
Type of Assessment Task Frequency of task Assessment Remarks
No. conduct
(Prorated
Marks)
Practical Worksheet (In Depending upon
Journal Category) and Class- 20 marks for each 8-10
1. 40 marks no. of
room experiment experiments
Learning experiments
At-least after the
2. Mid-Term Test 20 marks 1 per semester 12 marks completion of 5
experiments.

Discussion Forum/Short
3. Digital Assignment/Journal 4 marks for each task 1 per semester 4 marks  
to submit
design/Portfolio

4. Presentation* ------   Non Graded:  

Engagement Task
Attendance and BB End Semester
5. Engagement Score -----   4 marks

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Table 3.2: Assessment Patern
 Frequently Asked Questions

• What is orthographic projection?

• What are the basic requirements in order to draw projections?
• On which plane is front view drawn?
• How will be the front view of point A represented?
• What is the position of object in 3rd angle projection?

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 Recommended Books

• Rhodes R.S, Cook L.B; Basic Engineering Drawing, Pitman

Publishers,
• Rana and Shah; Engineering Drawing, Pearson Education India
Publishers.
• Jolhe D.A; Engineering Drawing: With an Introduction to AutoCAD,
 Tata McGraw Hill
• Gill P.S; Engineering Drawing, S.K. Kataria and Sons Publications.
• Dhawan R. K; Engineering Drawing, S. Chand and Sons Publishers.

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 References & Image Links

• Engineering Drawing by P. S. Gill

• Engineering Drawing by Dr. R. K. Dhawan
• Engineering Drawing and Computer Graphics by Harwinder Singh
• www.educationportals.net
• http://ednotebook.hostgator.co.in/theory-of-projection
• https://www.slideshare.net/kashyapshah11/projection-of-lines-127702
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THANK YOU

For queries
Email: paras.me@cumail.in

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