Chapter 3 Orthographic Projection

1. Chapter 3 Orthographic Projection

2. Object representation Multiview projection Glass box concept Orthographic projection of point, line, plane, surface and object. Line convention TOPICS

3. Axonometric projection Multiview projection OBJECT REPRESENTATION

4. Depth Height Depth Width Height Width Depth MULTIVIEW PROJECTION Three principle dimensions of an object … … can be presented only two in each view. Adjacent view(s) is needed tofulfill the size description.

5. TO OBTAIN MULTIVIEW REPRESENTATION OF AN OBJECT • Revolve the object with respect • to observer. • The observer move around the • object.

6. REVOLVE THE OBJECT Top view Right side view Front view

7. OBSERVER MOVE AROUND Top view Front view Right side view

8. THE GLASS BOX CONCEPT Rear view Left side view Bottom view

9. History Depth Width Height

10. Orthographic Projection of Object Features

11. OBJECT FEATURES are lines that represent the boundarybetween two faces. Edges Represent the intersection of two ormore edges. Corners Edge Edge No edge Corner No corner No corner

12. Surface Surface Surface OBJECT FEATURES are areas that are bounded by edges or limiting element. Surfaces is a line that represents the last visible part of the curve surface. Limitingelement Limit Limit

13. Equal distance PROJECTION OF POINT(S) BT BT AT AT B A BR AF BF BR AR AF BF AR

14. PROJECTION OF LINE True length BT AT BT Equal length AT B A BR AF BF AF BF AR BR AR Point True length NORMAL LINE

15. PROJECTION OF LINE True length BT AT BT Equal length AT B A A AF BR BF AF BF AR BR AR Foreshortened Foreshortened INCLINED LINE

16. PROJECTION OF LINE Foreshortened BT AT BT B Equal length BR BF AT B A BF BR AF A AF AR AR Foreshortened Foreshortened OBLIQUED LINE

17. PROJECTION OF PLANE True size CT BT CT AT Equal length BT AT C B CR A BF AF,CF BF AF,CF CR AR,BR AR,BR Edge Edge NORMAL PLANE

18. PROJECTION OF PLANE Foreshortened CT BT CT AT C Equal length BT AT CR CF C B CF CR A BF AF AR,BR BF AF AR,BR Edge Foreshortened INCLINED PLANE

19. PROJECTION OF PLANE Foreshortened CT BT CT AT C Equal length B CR BT AT BF CF C B CF BR BR CR BF A AF AR AF AR Foreshortened Foreshortened OBLIQUED PLANE

20. PROJECTION OF OBJECT The views are obtained by projecting all object features to the picture plane. You have to project the remaining surfaces which are invisible too !

21. s s s PROJECTION OF OBJECT

22. PROJECTION OF OBJECT

23. Line Convention

24. LINE CONVENTION Precedence of coincide lines. Hidden line drawing. Center line drawing.

25. PRECEDENCE OF LINE Order of importance Visible line Hidden line Center line

26. HIDDEN LINE PRACTICE Hidden line should join a visible line, except itextended from the visible line. Leave space Correct Join No !

27. HIDDEN LINE PRACTICE Hidden line should join a visible line, except itextended from the visible line. Leave space Leave space Correct No !

28. HIDDEN LINE PRACTICE Hidden line should intersect to form L and Tcorners. L Correct T No !

29. HIDDEN LINE PRACTICE Hidden arcs should start on a center line.

30. CENTER LINE PRACTICE In circular view, short dash should cross at the intersections of center line. For small hole, center line is presented as thin continuous line. Center line should not extend between views. Leave space Leave space

31. CENTER LINE PRACTICE Leave the gap when centerline forms a continuation with a visible or hidden line Center line should always start and end with long dash. Leavespace Leavespace Leavespace Leavespace