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

2. Lecture 3 Sunday, 14 June 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/lines of projection

3. Lecture 3 Sunday, 14 June 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

4. Lecture 3 Sunday, 14 June 2015 4 Parallel Projections

5. Lecture 3 Sunday, 14 June 2015 5 Perspective Projections

6. Lecture 3 Sunday, 14 June 2015 6 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

7. Lecture 3 Sunday, 14 June 2015 7 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 axonometr ic projections and multi-view projections. Effective in technical representation of objects

8. Lecture 3 Sunday, 14 June 2015 8 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.

9. Lecture 3 Sunday, 14 June 2015 9 Axonometric The object is tilted with all three coordinate axes are visible in any one view (PP projection plane)

10. Lecture 3 Sunday, 14 June 2015 10 Orthographic (Orthogonal) The object is at rest and two coordinate axes are visible in any one view (PP projection plane)

11. Lecture 3 Sunday, 14 June 2015 11 Multiview Projections

12. Lecture 3 Sunday, 14 June 2015 12 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

13. Lecture 3 Sunday, 14 June 2015 13 The six views

14. Lecture 3 Sunday, 14 June 2015 14 Angles First angle projection – European System Third angle projection – American System

15. Lecture 3 Sunday, 14 June 2015 15 First Angle Projection

16. Lecture 3 Sunday, 14 June 2015 16 First Angle Projection 1 How to draw plan and elevation?

17. Lecture 3 Sunday, 14 June 2015 17 First Angle Projection 2 How to draw end view?

18. Lecture 3 Sunday, 14 June 2015 18 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’.

19. Lecture 3 Sunday, 14 June 2015 19 Third Angle Projection

20. Lecture 3 Sunday, 14 June 2015 20 Third Angle Projection 1 How to draw plan and elevation? In 3rd angle projection planes are transparent and objects are viewed through them

21. Lecture 3 Sunday, 14 June 2015 21 Third Angle Projection 2 How to draw end view?

22. Lecture 3 Sunday, 14 June 2015 22 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’.

23. Lecture 3 Sunday, 14 June 2015 23 Example 1

24. Lecture 3 Sunday, 14 June 2015 24 Example 2

25. Lecture 3 Sunday, 14 June 2015 25 Example1 movie

26. Lecture 3 Sunday, 14 June 2015 26 Example 2 movie