Solid DNA blog

Blog about stuff on Solid Edge CAD software

A CAD smackdown – direct vs. parametric modeling

Yesterday’s CADalyst CAD magazine, host a webcast about “Direct vs. Parametric”.

Topic: When, why and how to use direct and/or parametric modeling in your business.include

I agree somewhat with Matt Lombard, I find the title of the debate inadequate. Let’s not forget that I have Solid Edge vision on the topic…

« .. First. The title. Direct v Parametric. Some of the panelists weighed in on this too. I think it would be better called Direct v History. Almost any name you could come up with has some flaw, but to me, the two competing interests here are Direct editing and History modeling… »

It is possible to have a design that combines direct editing and parametric.

Example if I take a direct editing function


I can push on one a face,


and a feature will be add to the pathfinder along with a parameter in the variable table associate to the direct editing move.

clip_image005 clip_image007


Now if we look from another angle, history vs. non-history.

Again, it is possible to have a design with both approaches.

It is possible to push on the same surface, without any entry being record in the history of the part.


If we push the comparison a bit further, it is possible to have the parametric without history. Here, no entry is found in the Pathfinder, however we have a parameter that controls the topology of the part.


Now what will be the real debate, related to the introdution of new technologies for modeling and editing?

Linear or nonlinear modeling?

Ok I am probably the only one to approach the debate with this vision, but I am firmly convinced that it reflects much better the real debate.

It is not whether we have a historic or not, if we have parameters or not, because he can mix all techniques in a single environment.

The question is how can I navigate within my design to create it or modify it?

Can I quickly change the behavior of my design to promote a change that has not been predicted?

Does the position of holes must always be defined in relation to the edge of the part, or the reverse may be possible?

Why I cannot lock a portion of my part, without affecting the rest of my design? *

Perceive the debate with a linear or nonlinear vision better reflects the true nature of the debate and helps better understand the cultural shock and transformation happening in the CAD community.


* For SW users who request the possibility to lock down some of the features, within synchronous you can define  a ground relation on a set of  faces, locking down their position in space. Non linear modeling supports this as a native behavior.


25 February 2011 - Posted by | Synchronous Technology, Traditional Technology, Uncategorized, Webcast

1 Comment »

  1. I agree with you one some most of your comments the. The big question is not how fast can you put a model to together, but when a changes needs to happen how fast or easily can you make that change.

    My 2 cents is that history modeling has some advantages is helping make these changes, but not everything has to be driven by something else, and a lot of times it’s actually more work that way. It would be faster and easier to just graphically move those elements into the right position then to try and predict which way it should move when I create it.

    One of the panelist actually eluded to this by saying that when a person models there are only a few critical elements that need to be historically/parametrically driven.

    Comment by Dennis Nelson | 28 February 2011 | Reply

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