# Lecture 3 Sunday, 03 May 2015 1 ENGINEERING GRAPHICS 1E7 Lecture 3: Orthographic Projections.

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Lecture 3 Sunday, 03 May 2015 1 ENGINEERING GRAPHICS 1E7 Lecture 3: Orthographic Projections

Lecture 3 Sunday, 03 May 2015 2 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

Lecture 3 Sunday, 03 May 2015 3 Projections (2) Projections Parallel/ Cylindrical Oblique Cabinet Cavalier Other Orthographic Multi-view First-angleFourth-angleThird-angleSecond-angle Axonometric Isometric (30°) Di-metricTrimetric Perspective/ Conical One-PointTwo-PointThree-Point

Lecture 3 Sunday, 03 May 2015 4 Perspective Projections

Lecture 3 Sunday, 03 May 2015 5 Parallel Projections

Lecture 3 Sunday, 03 May 2015 6 Parallel Projections Projectors are parallel to each other but not perpendicular to projection plane Effective in pictorially representing objects

Lecture 3 Sunday, 03 May 2015 7 Parallel Projections Projectors are parallel to each other and perpendicular to the projection plane Effective in technical representation of objects

Lecture 3 Sunday, 03 May 2015 8 Axonometric The object is tilted with all three coordinate axes are visible in any one view (PP projection plane)

Lecture 3 Sunday, 03 May 2015 9 Orthographic (Orthogonal) The object is at rest and two coordinate axes are visible in any one view (PP projection plane)

Lecture 3 Sunday, 03 May 2015 10 Multiview Projections

Lecture 3 Sunday, 03 May 2015 11 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

Lecture 3 Sunday, 03 May 2015 12 The six views

Lecture 3 Sunday, 03 May 2015 13 Angles First angle projection – European System Third angle projection – American System

Lecture 3 Sunday, 03 May 2015 14 Sketching Views (1) Measure the overall width, depth and height of the object STEP 1: Draw the construction (thin) lines following the number sequence STEP 2: Top View Front View Right Side View

Lecture 3 Sunday, 03 May 2015 15 Sketching Views (2) Draw all the details using blocks STEP 3: Sketch the circles and corners using compass STEP 4:

Lecture 3 Sunday, 03 May 2015 16 Sketching Views (3) Draw the centre lines, hidden lines STEP 4: Lighten the construction lines and thicken the final lines.

Lecture 3 Sunday, 03 May 2015 17 First Angle Projection

Lecture 3 Sunday, 03 May 2015 18 First Angle Projection 1 How to draw plan and elevation?

Lecture 3 Sunday, 03 May 2015 19 First Angle Projection 2 How to draw end view?

Lecture 3 Sunday, 03 May 2015 20 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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