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

I, for one, would like to think that I could adopt and assimilate direct modeling. There are many times when I wish I could simply abandon the strict structure that I've made for myself for a "quick" change. BUT, I have to say, that when a sweeping change, fully and correctly updates the entire model and the applicable assemblies, it is most gratifying! I hope that there is room for the coexistance of both approaches for I would not want to lose one to gain the other . . .

David,

Do not mixup the Direct Edit with Dynamic Modeling concept.

You can 'drag' dynamically some geometric features, but that will eventually just update the history-tree parameters.

So you will still have a fully constrained model.

Dynamic modeling has no* relations, you can edit the geometry as is.

*Also CoCreate Modeling has the Advanced Design options to fit in some relations.

This could blend in perfectly for those who need more Dynamic, but cannot do without a few relations.

Perhaps the 80%-20% rule applies for both solutions today.

Let see how Project Lightning develops...

Hello Maurice,

The first thing your question brings to my mind is to turn it back around and ask you the opposite question. Will the CoCreate users ever expand to Parametric Modeling, or are they stuck in the explicit mindset?

I say this for many reasons. Let me try and explain myself while trying not to offend anyone. Here is my background so you can see where I am coming from.

I started using CAD Tools in 2001. I have used: Pro/E, Catia, Solidworks, Inventor, Ideas and CoCreate. Obviously I am not that great at some of them. I have the most experience with Pro/E. I am currently the MCAD support person here. We started out many years ago as a Pro/E company. As time went by other companies were purchased that used different CAD packages (one of them being CoCreate). I was hired, 3 years ago, to support all the engineers and help them all move to Pro/E as the main CAD tool. I have heard many different sides of every story. I have recreated hundreds of CoCreate parts in Pro/E to help the Pro/E design teams work with the models that the CoCreate team created originally. Just to point out, I said recreated not translated or imported.

Now, back to the reasons:

1. The original question points to a lack of experience with Pro/E. Maybe, even an effort to get out of having to use Pro/E.
   
2. I hear all the time that CoCreate is a different mindset then Pro/E so the engineers cannot switch because they will be unproductive.
   
3. There are many ways to model the same part, but it comes down to personal preference.
   
4. All CAD tools have pluses and minuses. Nobody can send out a blanket statement like: CoCreate is better than Pro/E.
   
5. All modeling mindsets have pluses and minuses and are clouded with personal preference rooting back to the CAD tool that the person has the most experience with.
   
6. From looking at our models (yours might be different), I would have to conclude that the freedoms CoCreate gives allows for poor modeling practices. Models I have seen in CoCreate are inconsistent from side to side, holes are misaligned, dimensions are carried out to 20 decimal places, geometry can not be manufactured, geometry gets cut away and new stuff added leaving weird geometry that is hard to manage, the list goes on.
   
7. Many of the projects the CoCreate team works on gets to a certain level of completeness and then gets outsourced when it comes to the details and drawings. The companies that do the outsource work have voiced complaints to me about the quality of the CoCreate parts that they have to recreate in another tool.
   
8. I have some preference to the history in Pro/E, because I like seeing how the part was designed and like to be able to edit the original sketches to modify the part. But, at the same time I sometimes I get frustrated with old history messing up what I am trying to create.
   
9. While trying to create features in CC I have continual problems with them failing. So, Direct CAD can also have problems in that regards.
   
10. In my oppinion Parametrics is something modeling cannot do without. If I specify that I want a hole to be 1 inch from the edge and then change the shape of the part that dimension must hold to my original design. Not stay were it was. If I move a hole, the fasteners in the assembly must move with it. I should not have to go back and move them manually. I know CC has a Parametric module, but the CC guys have told me they do not see the benefit.
    

I could probably keep going but I will leave it there for now.

I think that any engineer can learn to use Pro/E, just as you think any engineer can learn CoCreate. It all comes down to person oppinion and experience. If someone cannot put aside a mindset to learn a new one - they are not putting enough effort into it. It all comes down to what is your job, and what does your boss want you to do. I would put more effort in learning CoCreate, but I am supposed to support Pro/E. If that directive changes I will change. I might still hold onto my personal ideas, but I will change.

It is all up to the person to try and stay in the box or get out. It is not driven by the CAD tool as your original post suggests. No offense intended.

I find the "tone" of this question to be objectionable. Perhaps the original poster didn't intend for it to be taken that way, but if so, the OP needs to consider his use of language much more carefully before making this sort of commentary.

For the record, I am a long-time user of Pro/ENGINEER (with somewhat less experience in several alternative packages - IDEAS, Inventor, etc).

Also for the record, I use Lightwave, Maya, ZBrush, Mudbox, and so forth. TOTALLY different types of applications, with totally different sets of capabilities, and used for totally different purposes.

The question is... are we creating ENGINEERING work (which must be completely defined, completely inspectable, and completely repeatable)? Or are we creating "artwork" which can be adjusted "by eye" just so it "looks right?"

For doing a mechanical design, it's nearly impossible to do this sort of work in non-parametric types of tools. You simply can't do proper engineering work without the explicit, math-driven description of the critical working elements. You choose the right tool for the job.

On the other hand, if you're trying to come up with a shape for, say, a modern-art sculpture... Pro/E (or any other parametric math-based modeler) is really not the right tool for the job.

The phrasing of the OP's question is perjorative. It infers, not so subtly, that prefering the right tool for the right job is somehow "closed-minded." That the sole reason that some people prefer using parametric design practices is because "that's what they know" and that some other approach may be equivalent, or better, in any given circumstance.

His later comment about "hammers and screws" further drives home this perception on his part. But even that argument falls apart, because he then limits himself to "one tool or the other."

Here's the answer. If you have a design which you ever expect to need to modify, or to do variations on, or even adjust tolerancing on, and if that design needs to physically interface with any other design element, parametric solid modeling is the preferred approach. If you want to create complex, "organic" shapes, parametric solid modeling is not the perferred approach.

The two can be blended. Engineers have been doing this for as long as the tools have been available. There are many ways to blend "organic sculpted shapes" and "mathematically precise designs." In my experience, this is typically best handled by creating the "complex shapes" in a separate tool, and using the output of that tool as a "sculpted template" where the complex elements are copied into the new engineered part.

It would be very nice if there were a practical way to implement "Maya/Lightwave" style modeling into "3D parametric CAD" tools directly. However, there's a fundamental issue there, and as far as I'm aware, this has yet to be resolved. See, it's CENTRAL to proper engineering work to have clear, communicable, REPEATABLE mathematical definitions for engineering features. "Free form" modeling does not really have any allowance for this yet. Yes, it's possible to provide the full mathematical definition of every non-uniform rational bezier spline surface, I suppose... but this seems a bit unwieldy, doesn't it?

I have no doubt that the two types of modeling will, eventually, "merge." I think this will happen sooner rather than later... perhaps even starting to see mainstream use within the next five years or so. But as of today, the problem isn't that "parametric CAD users are closed-minded," it's that the two tools simply serve totally different, and in many ways contradictory, functions.

I used CoCreate for a long while before I started using ProE. A combination of the two would be welcome if they can pull them together in a rational manner

It's funny the religious battle the OP has re-awakened. Granted his language implied that dynamic modeling is better than constrained modeling. But some of the defensive responses from the Pro/E users are laughable. I am a long time CoCreate user - we started with ME10 / ME30 and were on board for SolidDesigner 1.0 all by HP in the beginning. But we also have Pro/E- we're at about a 5 to 1 ratio of CoCreate to Pro/E seats. Pro/E at the time was basically worthless (if you ask me). Both products and approaches have come a long way since them. But I have always thought the original product names were very telling "pro ENGINEER" and "solid DESIGNER". Invariably our Pro/E users are Engineers and CoCreate is much easier for our Designers. In our R&D / scientific apparatus environment, speed in modeling, the ability to completely change direction in the middle of the development, and the ability to reuse and modify other geometry, whether created in house or from outside, all made direct modeling the clear choice for our CAD standard. So it was surprising and a little scary when PTC bought CoCreate a few years ago. And I thought the schizophrenia they showed was entertaining (simultaneously touting the acquisition of the "best in class history based modeler" while renaming the CoCreate Dynamic Modeling marketing term to Explicit Modeling). If you ask me CoCreate was always Dynamic Modeling and Pro/E was always Constrained Modeling.

I do have to say the idea that you cannot use direct modeling for Engineering work is preposterous. Ultimately the resultant topology of the part is what defines it when it is instantiated in reality - in other words made. Both products allow for the creation of precise topology and therefore both can be used to create Engineering designs. I do agree that the direct approach allows the creation of imprecise and/or bad models as well as the ability to incorporate organic or product design features. One has to pay more attention to snapping and good modeling practices to produce accurate designs in CoCreate. This doesn't mean that constrained models are inherently better. It just means that it takes a degree of skill to operate either product and get good results. Also I wanted to point out the incorrect implication by an earlier reply that suggested all surfaces in CoCreate are splines. CoCreate is a non-uniform rational B-spline modeler. Non-uniform comes from the fact that it supports analytic surfaces (planes, spheres, cylinders, cones, and toruses) in addition to the splines which are required for all sorts of blends as well as organic surfaces. The powerful topological based modification algorithms rely on analytic surfaces all the time and also some embedded history information (like how a blend remembers where the edge originally was so that you can easily delete it or modify it).

From my experience, the liabilities of being forced to put your design intent into the model (the constrained method) is only apparent in two cases: 1. flat out extra time and effort to create the model (measured in terms of numbers of clicks or individual actions the operator has to do in order to model the required topology), and 2. the inability to make changes that violate the original design intent (captured in the constraint hierarchy). We have seen large projects come to a grinding halt when what seems like a small change needs to be made, but it is buried so deep in the structure and has so many dependencies that even the most skilled Pro/E user cannot easily resolve the issue. So I think the direct method is better for the conceptual design phase and/or working on other peoples models. The constrained method is better for mature designs and production designs were the up front effort of capturing the design intent pays off in the ability to handle the rippling effects of small variations on the design. I agree with another earlier reply that there is a great deal of satisfaction when you've set it all up and you make a small change (that doesn't violate the hierarchy), and the whole system reconfigures itself and the revised drawings fall out with nearly no effort - wow!

It is true that the base product of CoCreate doesn't let you do constraints. It is also true that the add-in module that lets you apply them isn't so great. You can turn it on and force two holes to stay aligned for example, or to maintain the distance from one side. But it is kludgy and not very robust. However it is very surprising how much you can do with topology methods alone. The direct modification algorithms Germany came up with are very mature and powerful. It really is no big deal to just grab the two holes and move them simultaneously when you need to. And many "features" can be recognized by the topology they are comprised of, requiring no history to grab them and manipulate them as as a unit intelligently.

The Creo demo did show off a lot of promise of blending the two paradigms. Like the NX demos I have seen, a blend of the two methods can be very powerful. I very much appreciate that PTC looks to be finally ditching the Pro/E interface. It helps to have a consistent look and feel over the different personalities the software will have. And this is a chance for them to streamline the interaction in a way they were never able to completely fix with Pro/E, even the latest build. I am optimistic at this point.

Returning to the OP's topic, and having seen the hints of what Creo will be like, I think it will be a learning experience for both direct modeling users and parametric modeling users. It is a brave new world. They will both have to get un-stuck in their thinking. Maybe there will then be peace at last in the CAD wars. So say we all.

It is certainly possible to fully control parts and assemblies parametrically in some Direct Modeling tools (CoCreate is the most capable one today). Capturing design intent is not something that is only possible in a traditional history-based environment.Here is a video I created some time ago showing this capability in CoCreate:http://www.youtube.com/watch?v=PNjwiKGbw58 All of the geometry I used in this video came from Pro/E through STEP (completely unintelligent geometry). In CoCreate (Creo elements/direct) there is no limit to the ability to parametrically control geometry - regardless of where the geometry comes from or how it was created. You can add this intelligence during model creation of afterwards. Add it when it makes sense and only add what is needed. Here is another video that further supports this concept: http://www.youtube.com/watch?v=bXxv2HVnunw

The big difference between parametric (history-based) and direct (history-free) is in the inherent parent/child relationship that comes with the history tree. There is no concept of this in Direct Modeling. But that doesn't mean that you can't parametrically define relationships. In history-based modeling the relationships are solved linearly through the parent/child relationship. In "Creo elements/direct" these relationships are solved synchronously (simultaneously). Siemens ST uses similar technology, but they rather make many parametric assumptions whereas in CoCreate a user is more specific about the relationships that are defined.

Paul

http://p-hamilton.blogspot.com

Hi, guys

It’s nice to see that the long lasting “confrontation” between parametric modeling and direct modeling is still alive. Let me point on one aspect of this problem that, to my mind, is underestimated by the community.

To begin with, I would like to insist that the integration of these two approaches to 3D modeling is absolutely must to have for any advancement in the CAD industry that pretends to revolutionize the CAD market (though I do believe that somebody may have a different opinion).

But I would like to say even more – this long waiting integration is already successfully implemented, at least in 2D world.

Let’s forget for a moment that we are living in the 3-dimensional space. Imagine that our world is 2D.

Now let’s consider the 2D Sketcher of Pro/E not as a tool for constructing features of 3D parts, but as the 2D CAD application of itself. Then you can notice that the direct modeling approach is fully implemented here (for the 2D world we are living now). Certainly, for this 2D world the direct modeling is quite simple – you just need to drug-and-drop whatever you want using mouse (but this is everything you need for “direct modeling” in 2D case). On the other hand, you, certainly, have all the parametric capabilities in the Sketcher of Pro/E (actually, it is the 2D Sketcher, where all the “parametrics” of Pro/E is mainly live).

In other words, Sketcher of Pro/E has everything necessary and sufficient for both parametric and direct modeling on 2D plane (at least until the sketch is simple enough and Sketcher’s solver is able to resolve it in real time while you move a mouse).

The question is – if this marriage of the parametric and direct modeling resulted in such a happy family as the Sketcher of Pro/E (and similar sketchers of Pro/E competitors – SolidEdge, SolidWorks, Inventor, etc.), why not to repeat this experience in 3D world? That is, why not to implement the full functional 3D Sketcher?

Let's imagine an application that has the same look and feel as CoCreate (with all its direct modeling tools) but having additional tools for setting all reasonable geometric constraints on 3D entities (analogous to 2D constraints of 2D Sketcher). And, certainly, it should have a capability to resolve in real time the corresponding system of equations while you are applying the direct modeling tools (shift or rotate some faces, modify surfaces, and so on, and so forth)…

Ay, there is the rub! The systems of equation that have to appear from the constraints in 3D space are definitely must be much more complicated than those we have in 2D Sketcher. Besides this, as you surely remember, in Pro/E we are using “dirty trick” – I mean the famous “feature based approach”. Pro/E doesn’t solve the system of constraint equations for the whole 3D part. Instead it solves the hierarchic sequence of the smaller systems of equations for the features of this part (more precisely, for the underlying 2D sketches of these features). It simplifies calculations but it causes all the drawbacks of the history-based modeling.

To my mind, if we want to merge direct modeling and parametric modeling we need to go away from hierarchic features (i.e. say “farewell” to history-based approach) and resolve parts as a whole.

You can consider this “feature based” trick as a genius approach. Moreover, the whole philosophy was developed behind the feature based approach - they say that this hierarchic tree of features is the expression of the intension of a designer. But, to my mind, the reality is more prosaic. I guess that this trick was invented in the early days of Parametric because there was no way out. At that time there was no chance to solve really big systems of equations.

Actually, this is the point that I wanted to pay attention to. From those glorious times of the PTC’s childhood a great progress was achieved in solving really huge systems of equations (with hundreds of thousands of variables) similar to those resulted from geometric constraints. Having this in mind, I would like to ask everybody who has any guesses on the topic:

1. Am I right that the root of the problem of unification of the direct modeling and parametric modeling in 3D lies in the developing a really powerful solver that is able to resolve (in real time) big 3D complexes?
   
2. Am I right that any real breakthrough in the CAD industry have to be based on the development of such an advanced solver?
   
3. Should we expect such a breakthrough in Creo 1.0 (or 2.0, or 3.0 …)?
   

I do apologies, if somebody considers my tone “objectionable”. I have a great respect to PTC as a pioneer of parametric modeling and wish any success to the declared revolution. My only intension was to describe the landscape as I see it…

Frankly speaking, when I'm thinking about Creo initiative, these questions bother me.

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

All,

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.

http://communities.ptc.com/blogs/hello_cad/2011/01/25/versus

Bettina

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