First let me confess to not having paid sufficient attention to the “direct modeling” wave that’s flooding the CAD market. While the technique isn’t new, it’s made substantial gains in recent years… both in the release of some interesting new modeling applications (e.g. SpaceClaim) and noteworthy upgrades (e.g. Siemens NX5), as well as in significant investments (e.g. PTC acquiring CoCreate in Dec 2007).

I recall reading about TriSpectives (it and Rhino3D were reviewed in the same CADalyst article way back in July of ’95) and the early days of its spin-off, IronCAD, but I didn’t keep tabs on the solutions they were bringing to the table as I had gotten comfortably numb in the approach I was using. Those solutions, however, seem to have come of age and are definitely worth my attention now.

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As a brief review, here are a few excerpts from Wikipedia’s “Solid Modeling” page (Link) – and a couple of other sources (cited) – explaining the various 3D CAD modeling approaches that seem most relevant to this discussion:

Feature based modeling

Parametric modeling

(see also: PC Magazine definition of “parametric modeling” – Link – and MCAD Online’s “Parametric Modelling history” – Link)

Direct Modeling

(see also: Schott Systeme’s excellent video documenting this process – Link; highly recommended viewing.)

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Now I can just hear some of you asking, “This is all well and good, but what the hell does this mean and why should I care?”

The simple answer I deduce from this bit of research into “data portability” – and how the market is dealing with issues affecting efficient collaboration – is that the 3D CAD market has effectively forked into two branches: the parametric feature-based history tree applications, and those using a variety of “direct modeling” approaches (I’ve come across a few flavors, so I’m hesitant to apply the same label to them all).

This division may or may not continue into the foreseeable future. Perhaps it will; similar to how “solid modeling” (e.g. SolidWorks) and “surface modeling” (e.g. Alias Studio) have traditionally coexisted. However the markets those products have served have already begun to converge (i.e. increasing numbers of industrial designers are using solid modeling CAD applications, and more engineers are using surfacing applications).

I can easily imagine a time when there are no distinct markets. Furthermore, there is certainly a chance we’ll see more of what we saw when PTC purchased CDRS: they integrated the surfacing functionality into Pro/ENGINEER and killed it off. And PTC has, like other vendors, already implemented some “direct modeling” capability into their flagship product, so it’s possible that their CoCreate acquisition will follow the same assimilation blueprint.

What’s important to understand, I believe, is that “direct modeling” is, as far as I can tell, closer to the kind of 3D modeling used for virtual worlds and videogames. Consequently, products which are designed to manipulate faces on solid 3D geometry (e.g. Kubotek’s “Face Logic”) are likely to find themselves linked to virtual worlds such as Second Life or Multiverse; or to open source metaverse applications such as OpenSim or Wonderland or Croquet.

The bottom line seems to be that 3D CAD solid-modeling applications are primed to link up with virtual worlds.

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In my next entry I’ll get back to data portability and then provide some examples of how some CAD applications are already making their move.