Monday, October 18, 2010

Solid Edge ST3, My First Impressions (part 2)

In Part 1 I described my observations regarding how Solid Edge ST3 lines up with some of the typical issues related to traditional parametric history-based modeling. In this Part 2 I will share some of the other crazy observations I have:

Here is a statement coming from “You no longer have to choose which modelling workflow to use up front, instead it is a simple case of switching between ordered (traditional) and synchronous whenever required.” And, by the way, if you “switch”, or move an ordered feature to Synchronous, there is no going back. It’s a one way trip. Siemens still provides no ability to rationalize the history-tree (ordered) from a direct model/feature (synchronous). Something that Autodesk is struggling to solve with their Change Manager. With SE ST3 it seems real simple to move ordered features to synchronous. Since it is a one-way trip, I wonder how long it will take before all your Solid Edge history-based (ordered) data is completely history-free (synchronous/unordered).

When reading about SE ST3 I started having flashbacks to the mid 90’s. This started sounding strangely familiar. At the time I was fairly close to the developers of TriSpectives at 3D/Eye, now known as IronCAD, (CAXA in China). Here is a good article with some of the IronCAD history. IronCAD has always been and is still a parametric history-based system at its core. Although it was only a few years ago that they exposed the history tree structure to the user. Due to the systems ability to automatically reorder the tree structure, it was infrequent that a user actually needed to manipulate the structure manually. IronCAD did several things different from traditional history-based modeling systems. I had included much more detail on IronCAD while writing this but as I was writing Deelip Menezes published an extensive review of IronCAD. So I will refer you to his review for more detail on the similarities of IronCAD and SE ST3. In summary there are many similarities, although IRONCAD has been providing this type of "mixed mode" capability for many years now.

It seems to me that the synchronous features in the ST3 tree simply represent a single B-Rep model organized somewhere in the tree. You might consider it what other parametric history-based systems refer to as the “base feature”, although with ST3 this B-Rep is ordered somewhere in the tree, and can contain UDF’s (user defined features). In ST3 these UDF’s are actually defined by a modeling operation. When you drag and drop a feature from ordered into synchronous, you are simply taking the geometrical results of an ordered feature and adding that geometry to this single B-Rep, and then removing the ordered feature definition. This single B-Rep becomes more complex, or detailed, with each addition. The resulting new faces in the B-Rep are tagged to keep them grouped as a UDF. Am I over simplifying this?

I am not saying that any of this is bad. On the contrary I like to see this kind of stuff pushing all of us in our thinking of CAD. But as you are considering this, just keep in mind what our ultimate objective really is; and that is - designing products (sometimes 3D models can help us do that).



Dmitry Ushakov said...

Very interesting, Paul!

It seems to me that the synchronous features in the ST3 tree simply represent a single B-Rep model organized somewhere in the tree.

My own impression is that sychnronous technology implements so-called declarative feature definition based on geometric constraints. You can find more details in my recent note Synchronous Technology: The Third Attempt.

Paul Hamilton said...


Thanks for posting the link. An excellent post.


Sandip Jadhav said...

Very useful information about ST3!

Joe Brouwer said...

Hi Paul,

I was notified of this article by the link to my website.

I started my CAD life with Computervision and was introduced to CADKEY while at Boeing. To make a long story short, I started selling CADKEY. Solids showed up based on ACIS. I then found Trispectives. I was doing, with CADKEY (The ultimate mechanical package) and Trispectives (The incredible graphics design package) things that rival any package today.

I did try and sell Pro/E and Solid Edge. But I just couldn't warm up to the Pro/e paradigm of separate part, assy and drawing.

I don't have access to SE any more and I have a question. Does it still have the separate part, assy and drawing modes?

The big difference with IronCAD and a few other programs is what I have coined the UDE (Unified Design Environment) where you do all of your design in one file if you want.

I have described it here:

UDE (Unified Design Environment)

Four Functions that Increase CAD Productivity!!

I have sold, supported and used IronCAD for years.

Thanks for the reference.

Paul Hamilton said...

Hello Joe,

Thanks for your comments and questions. Doing “all of your design in one file” is not necessarily related to having a single “unified” environment for parts and assemblies, but I think I understand what you are saying. Solid Edge still has Assembly and Part modeling modes. All history-based systems have to have some recognition of whether the user is working on a part or an assembly, and the system has to know which part or assembly is being worked on. This is the case because the system is recording every modeling and assembly operation the user is making. These operations have to be recorded into the appropriate object tree structure. As such, when these systems startup, they will expect the user to answer the question: “are you working on a part or an assembly?” and the system will start in the appropriate mode. One part or one assembly has to be active at any time. This is still the case with Solid Edge and most any other history-based system. Where improvements are being made in history-based modeling is in better integrating the part and assembly environment and allowing part modeling to be done in an assembly view, and allowing referencing of other parts during editing - although it is still required to have either a part or an assembly active – no two objects can be active/edited at the same time.

The only alternative to this is pure direct modeling. In pure direct modeling since we are not recording anything we can edit the geometry of multiple parts, and position parts all at the same time in one operation – without constraints or a parent-child relationship, as seen in this video with the Drill Press: - a truly unified, in-context, environment. Unfortunately most of the newer direct modeling systems still may not have unified environments very well.