3D Modeling Debate Spurs New Generation of CAD Tools

In some ways, it's the CAD industry's version of thoseage-old debates, like the one over Coke vs. Pepsi, or republican vs. democrat.As the discourse heats up over the merits of traditional parametric, orhistory-based modeling tools compared with a new breed of direct modelers, theonly clear winner may be engineers, many of whom were previously shut out fromusing CAD and who are now increasingly being presented with a range of powerfuland flexible options.

Led by the introduction of PTCPro/ENGINEER more than 20 years ago, parametric or history-based modelinghas dominated the CAD scene with a handful of direct or explicit modelershanging out there on the fringes. Parametric modeling leverages a history treeto bring control and intelligence to the process of building CAD models. Theapproach gained traction over the flexible, but functionally-limited, directmodeling paradigm over the years because it was viewed as a more powerful andautomated way to create complex models, especially for large assemblies thatuse families of parts.

Yet in the last several years, parametric CAD modelers lostsome of their luster. Users have run into roadblocks due to the complexity ofthe history tree and they often complain about the inflexibility of the toolsfor doing conceptual work and last-minute design changes. Their concernsrekindled the decades-old argument, which has come back with a vengeance thislast year as newcomers like SpaceClaimrolled out new direct modelers that address many of the shortcomings of theoriginal class of tools. Following suit, history-based CAD leaders like PTC, Siemens PLM Software and Autodesk have come to market with their ownvariations on the technology, including a new hybrid breed that claims to marrythe benefits of both approaches.

In addition to ease-of-use and ease-of-learning, directmodelers also have an edge when dealing with multi-CAD environments, asituation made all the more common today due to globalization and the influx ofextended design teams. "Most companies are partnering with companies that havelots of different technologies and most can't afford to have a seat of NX,Pro/E, SolidWorks or Inventor sitting around in their design shops," says Monica Schnitger, a market analyst with Schnitger Corp. "By removing theconcept of the history tree, direct modelers function as a common groundplatform."

While there is a fair share of marketing hype surroundingthe competing modeling approaches, Evan Yares, a long-time CAD industryconsultant, acknowledges that a CAD revolution has indeed arrived - one thatwill make CAD experts far more productive, while opening the door to non-CADtechnicians who have previously been shut out from effectively using thetechnology. "All these different approaches are coming at the same problem - makingCAD easier to use," says Yares, who claims only 30 to 40 percent of engineerscurrently use CAD effectively. "What is comes down to is the modern CAD programhas become so complex, with so many commands, that a normal person can't runthem."

Separate, But Equal

That was the whole premise behind the introduction ofSpaceClaim Engineer, which was initially released to the market in April 2007with the fourthiteration announced last month. The CAD upstart was predicated on takingadvantage of inexpensive PC hardware to unleash a new type of CAD tool thatwould have appeal for the enormous untapped pool of designers and engineers forwhom traditional parametric-based tools were overload. "We see direct modelingas the vehicle to break out of the glass ceiling of 1 million seats of solidmodelers sold and to get an order of magnitude of new growth in the market," saysBlake Courter, co-founder of SpaceClaim.

SpaceClaim Engineer doesn't attempt to unseat traditionalCAD tools, but rather appeal to engineers and designers upstream in the processwho are not traditional users of CAD. In addition, the software - which officialsare quick to point out requires minimal training - is positioned as an adjuncttool within an engineering organization, optimized for quick conceptualizationof new designs or for preparing CAD models for analysis, according to ChrisRandall, SpaceClaim CEO. "This is 3-D modeling for engineers as opposed to 3-Dmodeling for CAD jocks," he says.

PTC also views the market for direct modelers and parametricCAD tools as mostly a separate audience. The company's flagship program,Pro/ENGINEER, is ideal for the majority of instances when products are complexand highly engineered, for example, or when the capture of engineeringconstraints and relationships is critical to the success of the design - especiallyif the product strategy is family-based or platform-driven. Yet even PTC, whichinvented parametric, recognizes the door is open for a different approach. Lastyear, PTC acquiredCoCreate, one of the oldest and more successful direct modelers, along withKubotek'sKeyCreator, and the company believes there is ample opportunity to grow theexplicit modeling category far beyond where it stands today.

While PTC doesn't rule out the possibility of eventuallybringing the two technologies together, for now, the company believes the twomodeling approaches appeal to distinct needs and audiences, thus are bestaddressed as separate products. Engineers should choose between the two disciplinesbased on the types of products they create, the time to market forces thatdrive them and the types of processes that define their workflow. "If you tryto put two fundamentally different technologies together, it's somewhat of arisk that you'll end up with the worst of both rather than the best of both," saysJustin Teague, PTC's senior vice president of CoCreate sales. "If you put toomuch constraining technology in explicit, you might lose some of theflexibility, whereas if you add too much freedom to parametric, you don'treally get the big bang for the buck that you're looking for out of thatapproach."

Even so, PTC has been adding direct modeling capabilities toPro/ENGINEER, as well as sprinkling in parametric-like functionality into CoCreate.Most of the major CAD vendors, including SolidWorksand Dassault Systemes are doing a lot of thesame cross-pollination, adding direct modeling functionality to their existinghistory-based products.

All Together Now

In fact, two of the biggest 3-D CAD providers have taken thecross-pollination strategy to a new level, blending both modeling technologiesin a single product. Siemens PLM Software launched its strategy last June, withSynchronousTechnology, which it touts as a history-free, feature-based modelingapproach now offered in both its NX and SolidEdge CAD products. Based on aproprietary application layer built on top of Siemens D-Cubed and Parasolidsoftware, Synchronous Technology employs live rules and solver technology toovercome the order dependencies that have frequently dogged the performance ofhistory-based CAD tools. Through this technique, Siemens is able to preservethe controls and automation advantages of a parametric modeling approach whiletaking advantage of the flexibility, direct interaction and scalability thathave been the hallmark of direct modelers, according to Dan Staples, directorof SolidEdge product development at Siemens.

Autodesk appears to be taking a similar approach with its Inventor Fusion technology, which itrecently previewed and is slated for a future Inventor release. Fusion technologywill enable engineers to switch between parametric and direct workflows as itmake sense for a particular task and the software will take responsibility forhow to bring the two models together and to track the changes in a singledigital model. "Customers need a two-way street," says Andrew Anagnost, vicepresident of CAD/CAE for Autodesk Manufacturing Solutions. "They want to beable to directly edit a model when they want to and lock it down in parametricwhen they want to. They want to keep parametric when they want it and throw itaway when they don't. That's what we've done with Fusion."

It's still too early to tell whether Fusion - or any of these new directmodeling technologies - will ultimately give engineers that ultimate level ofdesign freedom. One thing is clear, however; we're finally getting to a pointwhere engineers may soon benefit from the best of both worlds. "Parametric hassome very good points, but it also has some weaknesses," says Ken Versprille,PLM research director at CDP Assoc.LLC, a market research firm specializing in CAD and engineering. "Where weare today is getting to the point where we can avoid the weaknesses."

That is welcome news for Jonathan Gamble, director of engineering for Magnet-Schultz of America Inc.,a privately-held manufacturer of electromagnetic devices with headquarters inGermany. A long-time SolidWorks user, Gamble was getting pressure from theparent company to switch to the CoCreate SolidDesigner direct modeler, whichwas used extensively at the company's German divisions. Yet, Gamble said he had reservations. Thecompany's FEA tool and PDM system were not compatible with the CoCreatetechnology, and Gamble was concerned about how the lack of history-treetechnology would affect the design of families of parts, which was critical tothe Magnet-Schultz product family.

As a result, Gamble opted not to switch and keep both tools in house.Still, he's pleased by all the recent activity related to bridging the worldsof direct modeling with history-based CAD. "There's room for both. The trend Isee is that history-based modelers are starting to incorporate direct modelingfeatures. So in five years time, we'll have the best of both systems," Gamblesays.

All aboard the Direct Modeling Train: See how the new hybrids and direct modeling options stack up. Learn More