Power Tip

From CADD Master Ray

What's One More D?
Here's my first tip on 3D Drafting. It's not just one more D.

The incredibly simply idea of adding one more axis to the Generic CADD interface has many more implications that you might initially expect.

The name, 3D Drafting, is meant to imply that it performs many of the tasks traditionally associated with drafting, such as the creation of Axonometric and Isometric drawings, and the development of elevations, plans, and other orthographic projections. It also communicates the fact tha it has an interface which closely resembles 2D drafting programs such as Generic CADD.

The addition of the third axis, however, has what you might consider an exponential impact rather than an additive one. Rather than being half again as powerful as CADD, it's really an entirely different type of program.

In CADD, the restriction to two dimensions meeds that the drawings that you make are, by their very nature, flattened representations of three-dimensional objects in which your point of view is selected in advance. The database (the .DWG file) is a record of your flattened abstraction, not the real object. This is a Drawing.

In 3D Drafting, the lack of such a restriction allows the database (the .3DD file) to be a representation of the three-dimensional nature of actual objects in space. while still abstracted to a large extent, this database can no longer be considered a drawing. This is a Model. It is not reduced to a drawing until you select a point of view and convert it to a .DWG and print it out.

The superior value of a true model over a simple drawing is indisputable. While you can generate drawings from a model, the reverse is not possible. Selection of a point of view, while integral to the creation of a drawing, is independent from the creation of a model, and can happen at any time in the process.

Somehow, the addition of a third D seems to have added at least certain aspects of a fourth D as well, time. 3D Drafting has a database which is capable of being viewed from multiple viewpoints over time. You can draw in Isometric or Oblique, and then print your drawings in Perspective or Flat views.

As I will explore in future columns, the separation of the creation of "drawings" from the definition of a database within a drafting-style interface opens up the potential for many exciting new techniques and applications.