3D architectural modeling falls short of promise

1 Apr, 2001 By: Michael Dakan

Architectural CAD software developers seem to concentrate most of their development effort on 3D modeling these days. New architectural CAD software revolves around the premise that architects and building services engineers want to construct a 3D model and render it. While this is occasionally true, this approach is at least partially misguided. The financial reality of architectural practice is that design and rendering of models generates a relatively limited portion of the fees in most offices. Most day-to-day activity in an architectural or building engineering office involves creating construction documents, yet this aspect of architectural CAD receives far less attention than the more glamorous 3D modeling.

I have long supported the much-anticipated integrated 3D CAD model that produces multiple plotted views for construction documents. The economic benefits of creating live sections and elevations directly from a detailed 3D model are obvious, and I firmly believe that eventually we will generate much of our construction documentation directly from a 3D model. But that day hasn't arrived yet. In the meantime, we still have to produce the plotted hardcopy drawings that we use as the binding legal contract documents for building construction.

I have two primary concerns with the current state of architectural CAD software: the additional training and support infrastructure necessary to ensure that all users are proficient and productive, and whether the 2D graphical output generated from the 3D model is really sufficient for construction document purposes.

3D modeling gets better, but not easier

Software developers have made major strides toward creating software that generates design sections and elevation drawings from a 3D model. But the tools that architects, engineers, and drafters must master to construct an accurate and detailed 3D model are getting increasingly complex. CAD developers have responded with software that gives you more control of such things as wall configuration and how objects fit together. In turn, though, this introduces increasingly difficult and complex programs. CAD software is making some major advances toward addressing this issue, but the world of architectural design encompasses much more than the tools can currently construct with any degree of ease and control.

Architectural Desktop 3

Autodesk's Architectural Desktop 3 is a good example. It addresses many shortcomings in the first couple of releases and also adds significant new functionality. If you've been waiting for ADT to mature into a more usable product, you should take a close look at this release. Release 3 adds sufficient control over such basics as complex wall intersection cleanup and the creation of roofs and curtain walls, for instance. You can now create highly complex and detailed CAD models.

Release 3's User's Manual exemplifies the increasing complexity of software brought about by increased program control. This manual concentrates predominately on new and improved functionality for Release 3, yet it is thicker than the previous manual that covered the entire rest of the program. New terminology and concepts are abundant, many of them documented in terms that might be second nature to the software programmers but are often foreign to practicing architects. Teaching your users how to control the software is a daunting prospect.

Training issues

If you have a large user base to train, you need to implement a multitiered, long-term training regimen that addresses the most basic aspects of the software. You should identify a limited, simplified subset of program functionality that everyone needs to master to be reasonably productive, then introduce more advanced functionality over time.

For instance, multicomponent wall styles are useful if you want to create an accurate and intelligent 3D CAD model. But if you need a typical 2D construction document drawing, you don't have to master the use of wall styles, at least not to start. You can use a multicomponent wall style to show each of the components in a wall and preassign wall hatches for each of them. But if you produce drawings to be plotted at 1/810 scale, which is the standard for non-residential construction drawings, you very seldom want to have multiple component lines and hatches appear on the plot. A simplified use of the Standard wall style serves you well for a long time and avoids the complexity of wall styles and additional difficulties of multicomponent wall cleanup and control.

I recently helped an architectural organization implement Architectural Desktop 2 and spent quite a bit of time assessing the software and devising a training curriculum. We had to determine which essential aspects of the program to include in the initial simplified training curriculum, which aspects would require additional intermediate and advanced training later on, and which areas to avoid due to immature or incomplete functionality.

Architectural graphics

My other concern about using the 3D model to generate 2D construction documentation is whether, after you've gone to the trouble of creating the 3D model, the resulting graphics that you can generate are really suitable for the intended purpose.

Especially in structural and building services engineering, extracting views of 3D objects doesn't result in the abstract, diagrammatic drawings that we're used to seeing for these disciplines. Granted, some potential benefits come from presenting some aspects of engineering construction in 3D, but for the most part, these disciplines' drafting conventions have served their purpose for a long time. Convincing engineers that it's worth the trouble to construct a 3D model is doubly difficult if the resulting construction drawings are not in the graphic form they want.

It's possible that a resurgence of the moribund AutoCAD third-party developer market will create tools that more directly address the simplified diagrammatic nature of building services drawings. Many people in the AEC industries remain skeptical about the practicality of 3D modeling as an all-encompassing solution to drawing production, and rightly so given the current complexity of the CAD software necessary to produce a model.

Producing construction documents remains the bread and butter of architectural and building services engineering practice, and people need better tools to handle the basic drafting tasks associated with that work effort. A colleague of mine commented that CAD developers seem to believe that the drafting problem is solved, and so want to move on to something new and more exciting. In a later conversation with another colleague, I passed that comment along and got the reply, "Yes, and since when did drafting become ‘the drafting problem'?"

The answer, of course, is that drafting has been a multifaceted problem for the CAD manager since the advent of CAD.

Software developers ought to take another look at the more basic and fundamental aspects of AEC drawing production before investing all their development effort in the next big challenge.

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