ppt of solid modeling for cad
- 1. Active Learning Assignment On Solid Modeling GANDHINAGAR INSTITUTE OF TECHNOLOGY Computer Aided Design (2161903) Prepared By:- Ayush Upadhyay (150123119053) Guided By:- Prof. Dhaval Patel
- 3. Two-Dimensional Drawing 2-D is not ideal for representing 3-D objects 2-D has no Z axis 2-D is flat!
- 4. Three-Dimensional Modeling 3-D models include X, Y, and Z dimensions Allows better definition of three-dimensional objects There are three general types of 3-D models - Wire Frame Models - Surface Models - Solid Models
- 5. Wire Frame Models Oldest form of 3D modeling Old technology - not used today Model Contains edges and vertices Cannot represent complex surfaces No details regarding interior of part Ambiguous
- 6. Wireframe models are Ambiguous… What does this object really look like?
- 7. Wireframe Ambiguity (Cont.) Which face is front and which is back?
- 8. Surface Models Came after Wireframe models Still used today Model Contains edges and vertices and exterior surfaces Can represent complex exterior surfaces No details regarding interior of part Too ambiguous for engineering analysis
- 9. Solid Models Current “state of the art” Model Contains edges and vertices , exterior surfaces, and interior details Part is unambiguously defined May be used for engineering analysis
- 11. Why Solid Modeling? Recall weakness of wireframe and surface modeling Ambiguous geometric description incomplete geometric description lack topological information Tedious modeling process Awkward user interface
- 14. Solid model Solid modeling is based on complete, valid and unambiguous geometric representation of physical object. Complete points in space can be classified.(inside/ outside) Valid vertices, edges, faces are connected properly. Unambiguous there can only be one interpretation of object Analysis automation and integration is possible only with solid models has properties such as weight, moment of inertia, mass. Solid model consist of geometric and topological data Geometry shape, size, location of geometric elements Topology connectivity and associatively of geometric elements non graphical, relational information
- 18. Solid model representation schemes 1.Primitive instancing 2.Regularized Boolean set operations 3.Sweep representations. 4.Boundary representations (B-reps) 5.Constructive solid geometry (CSG) 6.Spatial-partitioning representations - Octree representation
- 23. Constructive solid geometry (CSG) Objects are represented as a combination of simpler solid objects (primitives). The primitives are such as cube, cylinder, cone, torus, sphere etc. Copies or “instances” of these primitive shapes are created and positioned. A complete solid model is constructed by combining these “instances” using set specific, logic operations (Boolean) Boolean operation each primitive solid is assumed to be a set of points, a boolean operation is performed on point sets and the result is a solid model. Boolean operation union, intersection and difference The relative location and orientation of the two primitives have to be defined before the boolean operation can be performed. Boolean operation can be applied to two solids other than the primitives.
- 24. Constructive Solid Geometry Methods Constructive Solid Geometry (CSG) performs solid modelling by generating a new object from two 3-dimensional objects using a set operation Valid set operations include Union Intersection Difference
- 26. Constructive Solid Geometry Methods (cont…)
- 27. Constructive Solid Geometry Methods (cont…) CSG usually starts with a small set of primitives such as blocks, pyramids, spheres and cones Two objects re initially created and combined using some set operation to create a new object This object can then be combined with another primitive to make another new object This process continues until modelling complete