Orthographic Projection

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ENGINEERING GRAPHICS
1E9
Created By:-Ravi Patel

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Projections (1)
• Projections transform points from n (here,
n = 3) dimensional space into a space of
dimension less than n (here, n = 2)
• Points to be considered,
– Location of object
– Location of observer
– Plane of projection
– Projectors/lines of projection

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Projections (2)
Projections
Parallel/
Cylindrical
Perspective/
Conical
Oblique Orthographic One-Point Two-Point Three-Point
Cabinet
Cavalier
Other
Multi-view
First-angle Fourth-angle Third-angle Second-angle
Axonometric
Isometric
(30°) Di-metric Trimetric

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Parallel Projections

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Perspective Projections

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Oblique Projections
• Projectors are parallel to each
other but not perpendicular to
projection plane
• An oblique projection shows front
and top surfaces that include the
three dimensions of height, width,
and depth.
• The front or principal surface of
an object (the surface toward the
plane of projection) is parallel to
the plane of projection.
• Effective in pictorially representing
objects

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Orthographic Projections
• Orthographic projections are
drawings where the projectors,
the observer or station point remain
parallel to each other and
perpendicular to the plane of
projection.
• Orthographic projections are
further subdivided into
axonometric projections and multi-view
projections.
• Effective in technical representation
of objects

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Axonometric
• The observer is at infinity & the projectors are parallel to
each other and perpendicular to the plane of projection. #
• A key feature of axonometric projections is that the object is
inclined toward the plane of projection showing all three
surfaces in one view.
• The length of the lines, sizes of the angles, and proportions
of the object varies according to the amount of angle
between the object and the plane of projection.

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Axonometric
The object is
tilted with all
three coordinate
axes are visible
in any one view
(PP projection plane)

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Orthographic (Orthogonal)
The object is at
rest and two
coordinate axes
are visible in any
one view
(PP projection plane)

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Multiview Projections

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Multiview Projections
• Front surfaces of object is parallel to
plane of projection
• Projectors or line of sights are
perpendicular to projection plane
• Projectors are parallel to each other
and originate from any point on object

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The six views

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Angles
• First angle projection – European
System
• Third angle projection – American
System

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First Angle Projection

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First Angle Projection 1
How to draw plan and elevation?

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First Angle Projection 2
How to draw end view?

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First Angle Projection 3
Points to remember:
• The ‘front view’ (or elevation) is the view
with maximum information.
•The ‘plan’ is below the ‘elevation’ (in
projection).
•The ‘end view’ is placed on the right if
viewed from left side of object and on the
left if viewed from right side.
•‘End view’ and plan face inwards from
‘elevation’.

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Third Angle Projection

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Third Angle Projection 1
How to draw plan and elevation?
In 3rd angle projection planes are transparent
and objects are viewed through them

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Third Angle Projection 2
How to draw end view?

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Third Angle Projection 3
Points to remember:
• The ‘front view’ (or elevation) is the view
with maximum information.
•The ‘plan’ is above the ‘elevation’ (in
projection).
•The ‘end view’ is placed on the right if
viewed from right side of object and on the
left if viewed from left side.
•‘End view’ and plan face outwards from
‘elevation’.

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Example 1

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Example 2

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Example1 movie

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Example 2 movie