Parametric Modeling

Parametric modeling takes a slightly different approach on 3d modeling.  It allows you to first
draw the figure, then you can extrude it three dimensionally. Parametric modeling also allows
you to set up restraints in your object.  Which is help "enhance design intent."  This type of modeling
keeps the relationships between an object and its various parts.

The first type of parametric modeling "to tie together all component views and annotations parametrically" was
Revit. I found this website http://www.csanet.org/newsletter/winter05/nlw0506.html that had a good example of parametric modeling compared
to CAD.  Further down it explains how parametric modeling
would be able to change the box by simple changing the
text, while CAD would have to delete the first box and
then create a new box to the new specifications. Parametric
modeling seems to be another reason why Revit puts CAD in
its shadow.

Parametric modeling not only allows users to create new
designs, but also to change an idea or object quickly.
The downside however is trying to adjust objects that
are irregularly shaped. Irregular objects are created
by adding part of other objects while taking away that
of others.  After awhile the steps get confusing and hard
to understand.