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The Changing Face of Parametric Modeling

Push-pull editing — commonly found in direct modeling programs like SpaceClaim, CoCreate, and Siemens products with Synchronous Technology — has now been embraced by many leading parametric CAD brands. Despite having Parametric for its first name, PTC or Parametric Technology Corp becomes the latest to implement push-pull functions. This appears in the company’s flagship Pro/ENGINEER Wildfire 5.0 software under the name Dynamic Editing.

Originally, the distinction between parametric and direct modelings seemed straightforward enough. If a CAD system let you construct and modify geometry by preserving a feature history, it was a parametric modeler. On the other hand, if it let you create and edit geometry on the fly — in other words, directly in 3D space — without bothering to record the process in a series of steps, it was a direct modeler. Regardless of the type of program you were using, you would most likely be executing your commands via menu bars and dialog boxes.

Now that you have the option to directly push, pull, poke, and pinch on surfaces and edges to reshape your geometry in both parametric and direct modeling programs, direct modeling may become a muddled term, up for grab, open to misinterpretation. At best, it risks confusion.

While many leading parametric CAD modelers have made it possible for you to directly interact with your geometry as described above (SolidWorks, Alibre Design, and Pro/ENGINEER, to name but a few), some direct modelers like Kubotek‘s KeyCreator continues to use an interface that relies on menu bars and dialog boxes instead of push-pull modeling. Yet, it creates and edits geometry without keeping a history tree, so strictly speaking, it’s a direct modeler.

If merging parametric and direct modelings into a single package (something Autodesk is publicly pursuing via Autodesk Inventor and Inventor Fusion) becomes the future of CAD, the distinction between history-based (or parametric) modeling and history-free (or direct) modeling might just become history — a moot point. Instead, you might care more about whether you can push and pull on your parts.

To illustrate my point, here’s a CAD blind test.

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About Kenneth

Kenneth Wong has been a regular contributor to the CAD industry press since 2000, first an an editor, later as a columnist and freelance writer for various publications. During his nine-year tenure, he has closely followed the migration from 2D to 3D, the growth of PLM (product lifecycle management), and the impact of globalization on manufacturing. His writings have appeared in Cadalyst, Computer Graphics World, and Manufacturing Business Technology, among others.


  1. Where is the coverage of Siemens PLM products — Solid Edge and NX? Do you really understand the capabilities in Synchronous Technology as included in these products. It is well beyound just direct modeling.

  2. Kim: Thanks for the comment! I inadvertently left out Siemens products in this post, so I’m thankful for your reminder. I just revised the post to include them.

    I have in fact covered Synchronous Technology. You can identify the posts tagged “Siemens” from the tag cloud in the right margin. In the interest of full disclosure, I should tell you I have not had a chance to use it first-hand, though I have seen demonstrations and briefings. (Siemens is selective about who gets access to its software, for justifiable reasons. We’re working with Siemens to publish a review of NX with Synchronous Technology in DE early next year.)

    Happy Holidays!

  3. SWX works very similar to wilfire, but SWX gives you one more advantage: in your wildfire video, one can see, that you enter the direct modeling changes in the feature tree (RMB > direct modeling) … in SWX, one can acivate the direct modeling as a global setting, and than you can pick each and every face directly, without searching the feature tree to find the right feature which has to be edited dynamically.

  4. Ulrich: Thanks for pointing this out. You’re probably correct. Unless I missed it, I didn’t see a way to make Dynamic Edit the default editing setting for the entire session in Pro/E Wildfire; I can only execute it one edit at a time, on one feature at a time.

  5. Alias for Inventor is very primitive, by modifying edges Inventor complex models hangs and does not perform the most basic operations and not to mention it in symmetry because it can not, in short Alias to Inventor is totally useless for truth surfaces, I hope In the future this application will improve by adding more tools and improving the calculation of operations.

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