The parameterization process consists in the specification of points, lines, curves or surfaces by means of one or more variables that take values ​​within user-defined ranges. Parametric modeling is an important resource for conceptual design, allowing precise control of design variations. Revit Architecture provides a complete set of parametric modeling tools, while both Maya and 3ds Max implement parametric behavior based on the modeling sequence. AutoCAD offers in its latest versions a parametric drawing environment that enables the creation of 2D geometric and dimensional constraints, in addition to dynamic blocks.

Parametric design involves a change in the way we approach design tasks. The usual way to work with AutoCAD so far has been to create lines, arcs, circles, etc.. geometric entities representing a preconceived design. Working like this, any modification of the design involves replacing some of those geometric entities to represent the new solution.

In the parametric approach the designer begins by establishing the relationships between the parts, building the design from these relationships and modifying them as the evaluation and selection of the results obtained advise. The software is responsible for maintaining the design's consistency from preset geometric and dimensional constraints. This will enhance the possibility of examining variations without the need to redoing each time the graphic representation. This requires a change in the designer's working habits so as to include the definition of relations, the logic that makes his design consistent as an essential phase in the design process. Within a parametric model, each entity has associated parameters. These parameters control various geometric properties of the entity, such as its length, width, height, radius, etc. They also control the location of these entities in the model and the way entities relate to each other. The parameters can be modified by the designer to create the desired geometry.

From the experience gained teaching Parametric Design courses in applications such as Autodesk Inventor and Microstation Modeler I have prepared a series of tutorials that I hope will serve as an introduction to this new approach to the design process for AutoCAD users.

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