• A model is used to mathematically capture some aspect of the
real world so that it may be manipulated, studied, tested, etc.
• To computerize a design we will capture a very explicit model
of a part in a computer program. • Geometry is by far, the most
important part of any design. It is used as a reference for
tolerances, processes, functions, materials, assemblies, etc. •
Three major functions in geometric modelling, • The Geometric
Representation determines what a system can do. • There are a
number of methods of representing geometry, 1D, 2D, 2.5D, 3D 2D
- All in one dimension, such as a side view of a part 2.5D -
Points have an x, y coordinate, and height. This is a special
case which can describe raised surfaces like buildings. 3D -
Full spatial dimensions • 2D models are quickly becoming
obsolete, 2.5D models were an early compromise, but 3D models
are quickly becoming the standard.