Lecture 3 Sunday, 14 June 2015 1 ENGINEERING GRAPHICS 1E9 Lecture 2: Orthographic Projections.

Lecture 3 Tuesday 18 April 2023 1

ENGINEERING GRAPHICS1E9

Lecture 2: Orthographic Projections


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


Projections (2)Projections

Parallel/Cylindrical

Perspective/Conical

Oblique Orthographic One-Point Three-PointTwo-Point

Cabinet

Other

Cavalier

Multi-view

Axonometric

First-angle Fourth-angle Third-angle Second-angle

Isometric (30°)

Di-metric Trimetric


Parallel Projections


Perspective Projections


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


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


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.


Axonometric

The object is tilted with all three coordinate axes are visible in any one view

(PP projection plane)


Orthographic (Orthogonal)

The object is at rest and two coordinate axes are visible in any one view

(PP projection plane)


Multiview Projections


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


The six views


Angles

• First angle projection – European System

• Third angle projection – American System


First Angle Projection


First Angle Projection 1

How to draw plan and elevation?



How to draw end view?



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’.


Third Angle Projection


Third Angle Projection 1

How to draw plan and elevation?

In 3rd angle projection planes are transparent and objects are viewed through them



How to draw end view?



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’.


Example 1


Example 2


Example1 movie


Example 2 movie

Lecture 3 Sunday, 14 June 2015 1 ENGINEERING GRAPHICS 1E9 Lecture 2: Orthographic Projections.

Documents

Transcript of Lecture 3 Sunday, 14 June 2015 1 ENGINEERING GRAPHICS 1E9 Lecture 2: Orthographic Projections.