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Will a Pro-e user ever expand to 3D Direct CAD, or is he stuck in a parametric mindset?

Re: Will a Pro-e user ever expand to 3D Direct CAD, or is he stuck in a parametric mindset?

@James Osborn

I just learned more about Direct Modeling from your post than I have from all the videos and information I can find on PTC's site.

I have been using Pro/E (Parametric Modeling) for over 16+ years. I never understood what Direct Modeling was or how it could fit into our process. I started to understand more and more about it, but never from an actual user who had real world experience with it.

I think it's exciting to see Parametric and Direct Modeling working together in CREO. I can see where our company would use Direct Modeling for some things and Parametric Modeling for others. Using them together, I think is a good way to get the best out of both system in order to improve our process.

I appreciate the information you shared and I am looking forward in learning more about the Direct Modeling approach. I have always been open minded about learning new things, so it's never a problem for me to sit back and learn something different.

I have a question for you.

Do you think having the Parametric Modeling App and Direct Modeling App in CREO is the best way to do things, or would you rather see CREO allow for both modeling systems in one package?

As it stands right now, it seems I will need to purchase Direct Modeling Apps for everyone in our process that could benefit more by this approach and have Parametric Modeling Apps for the others. I can see where many of my users could use both and now I have to buy more licenses (Apps). 😞

Just wondering what your thoughts are on this.



Re: Will a Pro-e user ever expand to 3D Direct CAD, or is he stuck in a parametric mindset?

Hi James

Thank you for your reply. May be, you are right and Creo demo looks promising (actually I enjoyed this presentation and like the idea of rebranding - the name Creo is really good). But this promise is too long-lasting.

Don't you think that not a big progress in Siemens PLM Synchronous Technology (ST1 -> ST2 -> ST3 -> ...) and the troublesome road to the marriage of CoCreate and Pro/E are the signs that this approach based on "solving local operations" has some inherent restrictions?

If you want to reach the real freedom to transform one 3D design into another (somehow similar but, may be topologically different) 3D design, you need something more powerful than local operations. And this more powerful "something" is the system of geometrical constraints covering the whole part (and the corresponding system of 3D equations), which requires a really powerful solver to resolve these equations.


If you want to design a supercar you can't use an engine developed 25 years ago. You need a totally new engine, most likely, based on the new principles.

My feeling is that this is the mainstream of the further CAD investigations, and such a powerful solver (a "new engine") is not a dream but the reality of the nearest future. I do wish to PTC to move in this direction. The new brave world is there...

Re: Will a Pro-e user ever expand to 3D Direct CAD, or is he stuck in a parametric mindset?

I though create did have a brand new engine built from the ground up. That is what I heard PTC say at least.

Just because CREO opens Pro/E files, does not mean it's using the 25 year old Kernel. From what I understand, the Kernel in CREO is brand new and patented. Maybe I am wrong here. Not sure.

Re: Will a Pro-e user ever expand to 3D Direct CAD, or is he stuck in a parametric mindset?

I would definitely rather work in an environment where both methods are available. I am guessing the way they handle the Creo Direct modifications when the model is opened in Creo Pro is that the direct modifications are like soft constraints. They are there, inserted automatically, as needed, so the model can regenerate in Creo Pro. So using both methods together might be like using direct modifications when you want, explicit constraints when you want, and sometimes switching soft constraints to explicit ones or vice versa. CoCreate lets you make many direct modifications using methods that look a lot like modifying a fully constrained Pro/E model. I presume they use the smart topology methods and just display the dimensions like they are constraints, but they aren't really. I would assume Creo Direct would use the same topology methods, and perhaps leave soft constraints in the model for later use by Creo Pro. This is all conjecture on my part.

From my perspective, I would rather have as few constraints as possible, only when I want to capture some design intent. There are a lot of cases where it would be nice even when doing direct modifications, to set up a few hard constraints you need. If it really is true the products will be totally separate, I would find myself in Creo Direct most of the time. Presumably this means it wouldn't enforce any hard constraints you put on the model in Creo Pro, so what would be the point? Conversely if I worked in Creo Pro most of the time, using soft constraints most of the time and a few hard constraints as needed, it would be a pain to have to save out and re-open in Creo Direct just to make a direct modification when I want.

I'd like to be in Creo Pro/Direct (if I might coin a new name) that would be parametric, use soft constraints most of the time, allow hard constraints as needed, AND support direct modification methods. In some cases like the demo, using a direct modification might simply result in cutting out or copying a feature branch in the history, and reinserting it somewhere else. Other times, it might be too hard and convert many constraints into soft constraints. I can't imagine it would be easy to really have both methods integrated into the same product, but that would be optimal.

Re: Will a Pro-e user ever expand to 3D Direct CAD, or is he stuck in a parametric mindset?

I guess we really don't know how much is new and how much is old code in the new product. I find myself concerned that the continued support of two product lines (standalone CoCreate + Pro/E, AND Creo Pro + Direct) cannot be long for this world. Unless they were able to abstract the kernel methods from CoCreate so that it can be "plugged in" with either Creo Direct or stand alone CoCreate, then it means that the old CoCreate interface will go the way of the dinosaur. This would be a shame IMO.

A more advanced system able to resolve local operations and have a more global approach like you are thinking might be possible. I just think that when the model complexity gets large enough, a purely global approach will bog. I hate bog. It is precisely how nimble that CoCreate is at making drastic changes that is what is so great about it. Throwing away the purely direct method in favor of a more sophisticated kernel that supports both methods might result in a parametric modeler with SOME direct modification abilities but at the cost of speed and flexibility. If you do your direct modification in a whiz bang fashion like the Creo demo showed or that CoCreate already does all the time, and then you have to sit there and WAIT a few minutes while the global solver gets all the parametrics straightened out, I'd say YUCK!

Re: Will a Pro-e user ever expend to 3D Direct CAD, or is he stuck in a parametric mindset?

3-D Direct CAD is probably a "Rhino" tool for Engineers. It is the same concept as Rhino and is invented to make things "easy". However "easy" should not be confused with "lurch" modeling, since many initial gains in the product cycle, will get lost later one during the product development cycle.

On the other hand, the Direct Modeling lacks the advanced features of the current parametric approach such Surfacing and ISDX

Re: Will a Pro-e user ever expand to 3D Direct CAD, or is he stuck in a parametric mindset?

It seems that a major downside of the 3D direct Modeling, is the ability to transform the model in a not so "natural" way; turning it to a more graphical/computer approach to modeling rathen than a real representatin of real life situations.

In the REAL WORLD you can not remove faces or surfaces, for example of a CUBE and find something hollow inside, but you can DO IT in Direct modeling !!!

A physical object in reality is solid inside and not hollow

I am afraid there is a recipe here that tolerates errors, misalignments and merging of surfaces

Re: Will a Pro-e user ever expand to 3D Direct CAD, or is he stuck in a parametric mindset?

How you can suggest that being forced to "consult your blueprint before beginning your model" (a direct quote from a Pro/E instructor during a beginning Pro/E class), so that you can make sure you have consistent constraints, is somehow more natural than whittling on a chunk of material the way you would if you throw it on a milling machine and start cutting, is beyond me! Generally speaking I find that CoCreate facilitates manufacturable parts because the basic methods used to create and modify geometry are very much like manufacturing operations. In many cases, when you go through the steps to create the model, you are in a sense doing dry run of making the part in the shop.

Seriously you parametric minded Pro/E users are really in denial if you continue to assume that direct modeling is somehow inherently inferior to constrained modeling. As I previously stated, both methods have pluses and minuses and both require a degree of skill to achieve accurate results. The ability to turn a solid model into a face part in CoCreate "could" be the result of poor skills. CoCreate is pretty good at dealing with this in two ways: Firstly when you turn a solid into a face part, the icon in the Structure Browser changes from a solid cube into a surface patch. Also the face colors change from the default buffed aluminum to a blue color. There are tools to create new surfaces between existing 3D edges and 3D curve tools to create new edges in space. Secondly, when you stitch a face part back into a solid by manually inserting the faces where holes lie, it automatically turns the part back into a solid, the default face color changes back to aluminum, and the icon changes from surface patch to solid cube.

The ability to turn a solid model into a face part in CoCreate can also be entirely intentional. It can be used by the expert user in some situations to model geometries that are difficult using the standard tools, whether they came through constrained or direct methods. And it can be used to heal or fix problems with imported geometry from outside packages - regardless of how the geometry was created. In some cases with strange "special" geometry, it can be faster to construct a part from scratch using the surfacing and curves available in CoCreate. Once it is turned into a solid and checked with Part Check, it is just as good as a model created using the solid tools and can be used to create drawings or drive CNC tools.

So if you are going to incorporate direct methods into the product at all (apparently the goal of Creo), then turning solids into face parts (and vice versa) is not only not a downside, but is in fact advantageous in many cases.

Re: Will a Pro-e user ever expand to 3D Direct CAD, or is he stuck in a parametric mindset?

I think the title more appropriate would have been: Would a pro-e user shrink to 3-D Direct CAD?

In such critical applications as Engineering, being foolproof should be the main objective of any CAD software. The fact that C.C. allows the user, either intentionally or not, to modify/change the original concept without regard to its original perception, sets up a situation when a blueprint/drawing may have edges, faces, curves and confusing lines unaccounted for and not related to the real geometry. One may argue, that this is a user’s fault, however the fact that You Can Do It, in itself represent a dangerous freedom that may be very costly later on. One reason why constrains exist, we may argue about it, is to show what the limitations are and how to prevent user screw-up’s.

Co Create has a very similar approach to the design as Rhino and Rhino and Pro-E currently compliment each other very well. I do not really see room for CC here. One may argue why not use Rhino for Mechanical Design?

Re: Will a Pro-e user ever expand to 3D Direct CAD, or is he stuck in a parametric mindset?


This is a very, very long thread and I think the focus of the discussion has changed over time - there is a difference between before and after the announcementn of Creo.

I have compiled some of my thoughts and how I interpret some of your comments in a separate blog post. Feel free to visit and comment.


PS: this article is pretty long, too, once I had started writing I simply couldn't stop 😉