1. INTRODUCTION TO GEOMETRIC MODELLING 20 September 2010

2. Content Introduction Types of 3D model 2D vs 3D Solid Modeling

3. Introduction 3D modeling is creating an object or a part which has 3D characteristics and can be viewed 3D Simply, the object has depth or thickness In 2D drafting or drawing, the object is normally drawn in XY direction. In 3D modeling, the object is drawn in XY and also Z direction

4. 3D Modeling

5. Object modeled in 3D can be rotated and view from any angle Generally, more complicated to create and produce compare to 2D

6. Types 3 main types: wireframe, surface and solid 3D Wireframe Modeling – Show the ‘frame’ of the object in lines – quite similar to 2D, however the object has 3D characteristics

7. 3D Wireframe Modeling

8. 3D Surface Modeling – has material/texture between the line of frame – normally no thickness – complex/advance curved surface may be produced

9. 3D Surface Modeling

10. 3D Solid Modeling – model is made from solid blocks by combining and/or subtracting – the solid blocks can be created by applying 3D operations on 2D object and/or adding and subtracting primitives

11. 3D Solid Modeling

12. 3D Vs 2D

13. 2D Vs 3D

14. Solid Modeling Solid model consist of volumetric information & surface info of an object Surface of the model represent boundary between outside & inside of the object Basic rule – all surfaces must touch another surface

15. Solid Modeling

16. Several different types of solid modeling – Primitive modeling – Constructive solid geometry (CSG) – Feature-based modeling

17. Primitive Modeling Objects described using basic geometrical forms. Common geometric primitives.

18. Primitive Modeling

19. Example:

20. Constructive Solid Geometry More flexible and powerful than primitive. Allow Boolean Operations: union, difference & intersection

21. Boolean operation

22. CSG: Example

24. Feature-based Modeling 3D model is built using series of features, such as hole, slot, square block, etc. Each feature can be independent or linked to other feature. The geometry of each feature is controlled by modifiable constraints and dimensions.

25. Feature-based Modeling

26. FBM: 3D operations Basic concept – 2D cross-section or profile is produced – Depth is given to the profile Generally 4 types – Extrude – Revolve – Sweep – Blend *different terms might be used in different software/books*

27. 3D Ops: Extrude A linear sweep, where the profile is given a depth in straight line, perpendicular to the profile plane Cross-section is constant, start – end

28. 3D Ops: Extrude

29. 3D Ops: Revolve The profile is rotated around a defined axis, 0 – 360 degree Cross-section is constant

30. 3D Ops: Sweep The new command and is similar to the EXTRUDE command, but it concentrates on using paths to define the direction of the extrusion. This command SWEEP a 2D object along a path

31. 3D Ops: Sweep & Blend

32. Steps in building 3D object

33. Examples of FBM + boolean