|
|||||||
|
|
|
|||||
|
|
|||||||
CAD (Computer Aided Designing)
CAD can be defined as the use of computer systems to assist in the creation, modification, analysis, or optimization of a design.
The CAD hardware generally includes the computer, one or more graphical display terminals, keyboard and other equipment.
The CAD software consist of the computer programs to implement computer graphics on the system plus application programs to facilitate engineering function of the user. Examples include Stress-Strain Analysis, dynamics response, heat transfer calculation etc.
Some Common Editing Features on a CAD system.
1, Move an item to another location. This involves the translation of the item from one location to another.
2. Duplicate an item at another location. The copy function is similar to the move function except that it preserves a copy of the item at its original location.
3. Rotate an item. This is the rotation transformations, in which the item is rotated through specified angle from its original orientation.
4. Mirror an item. This creates a mirror image of the item about a specified plane.
5. Delete an item. This function causes the selected segment of the model to be removed from the screen and from the database.
6. Hide an item. Remove an item from the display without deleting it from the database.
7. Trim a line or other component.
8. Scale an item. A selected component can be scaled by a specified factor in x, y and z directions. The entire size of the model can be scaled, or it can be scaled in only one or two directions.
CONCATENATION
Matrices can be concatenated with other matrices. Concatenation is equivalent to sticking two matrices together such that a point first passes through one matrix and then the next during a transformation.
Concatenation is not commutative i.e. if A and B are matrices, then A time B is not necessarily equal to B times A. For example, rotation matrix times a scale matrix does not necessarily give the same result as a scale matrix times a rotation matrix even though the component matrices are identical.
Two examples of where combination of transformation would be require would be :
- Rotation of the element about an arbitrary point in the element.
- Magnifying the element but maintain the location of one of its points in the same location.