LECTURE 4

ISOMETRIC VIEWS.

& PROJECTIONS

Engr. Ali Raza KhalidCivil Engineering drawing

ISOMETRIC PROJECTION• “Iso” means equal and “metric projection” means a projection to a

reduced measure. • Isometric projection is a method for visually representing three-

dimensional objects in two dimensions in technical and engineeringdrawings. It is an axonometric projection in which thethree coordinate axes appear equally foreshortened and the anglesbetween any two of them are 120 degrees.

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PROJECTIONS

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ORTHROGRAPHIC PROJECTION

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ORTHROGRAPHIC PROJECION looking through the plane(Plane between observer and object)

ORTHROGRAPHIC PROJECION looking Directly at object(object between observer and plane)

OBLIQUE PROJECTION

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OBLIQUE PROJECION looking through the plane(Plane between observer and object)

OBLIQUE PROJECION looking Directly at object(object between observer and plane)

PERSPESTIVE PROJECTION

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PERSPESTIVE PROJECION looking through the plane(Plane between observer and object)

PERSPESTIVE PROJECION looking Directly at objective(object between observer and plane)

VIEWS

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Perspective: Used more with freehand sketching. Parallel lines appear to

converge and meet at what is referred to as the vanishing point. You can have

one, two or three vanishing points (VP).

Isometric: Receding lines drawn at 30º and are usually kept at true measured

lengths.

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Oblique: Front face sketched as a true shape. Starts with two axes, one

horizontal, one vertical. The third axis is usually drawn at 45º and lengths are

reduced by 50% of true lengths. Sometimes called 'cabinet' projection

PROJECTION PLANES

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ANGLE PROJECTION

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Four Quadrants

ANGLE PROJECTION

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3rd Angle Projection 1st Angle Projection

Projections created with the object placed in the first quadrant are said to be in FirstAngle projection, and likewise, projections created with the object placed in the thirdquadrant are said to be in Third Angle projection.

ANGLE PROJECTION

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ANGLE PROJECTION

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Both systems of projection, First and Third angle, are approved internationally andhave equal status. The system used must be clearly indicated on every drawing, usingthe appropriate symbol.

ANGLE PROJECTION

The component:

Your drawing will, for this example consist of four views:

– • Front F

– • Left L

– • Right R

– • Plan (Top)

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FIRST ANGLE PROJECTION

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Engr. Ali Raza Khalid Civil Engineering drawing

THE END !!

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