History-based, parametric, history-free, direct, explicit, synchronous, dynamic, instant...
Over the last few years CAD companies have introduced many new terms as they have announced new product capabilities. Most significant are the capabilities related to direct geometry interaction and manipulation. The industry is becoming more familiar with the concept of history-free modeling (direct modeling, direct editing). As the awareness grows, the industry is trying to understand just what this technology means to the product development process. Unfortunately for many it’s still a bit confusing.
Is this history-free direct modeling technology complementary to our parametric history based environment or is it perhaps a replacement? Being part of the CoCreate organization inside of PTC I have witnessed many companies purchasing CoCreate for a variety of reasons. Many have completely replaced their old history-based environment with CoCreate, but many have also added it to their history-based environment as a complementary tool. In either case many companies are seeing significant benefits with history-free direct modeling.
It can certainly be a bit confusing for product development organizations to understand how this history-free technology can bring value and how it fits into the process. The confusion I am referring to is for the most part a result of how many CAD companies are positioning this technology. For example:
- Siemens introduced Synchronous Technology in 2008. Today they continue to claim: “Synchronous Technology unites parametric and history-free modeling”
- In 2009 Autodesk gave us a preview of their Fusion technology. They claim that Fusion “unites direct and parametric workflows within a single digital model”
I have had many discussions with people that have been confused by these statements.
Synchronous Technology does in fact unite parametric “control” with history-free modeling, to a certain extent. But unfortunately most people consider parametric modeling synonymous with history-based modeling. Synchronous Technology absolutely does not unite history-based modeling with history-free modeling. The two technologies may sit under a common UI, but they are very separate. Either the user is in a history-based mode, recording every modeling operation -OR- they are in a history-free mode where modeling operations are not recorded. It’s one or the other.
Autodesk does an even better job at confusing the situation. In Autodesk’s statement above they are in fact referring to history-based modeling when they use the term “parametric workflow”. They are also referring to direct modeling in the term “direct workflow”. My first source of confusion is in the concept of a “direct workflow”. There is actually no such thing. Certainly with history-based CAD there is a workflow to consider as every step you take is recorded and will impact the future use of the model. No such concept exists with direct modeling.
The Autodesk statement also suggests the possibility of uniting history-based modeling with history-free modeling with the term “single digital model”. What Autodesk has done with Fusion, a history-free tool (that creates a new file), is to provide technology that can analyze a history-free model coming from Fusion in such a way that the history structure and features of a history-based model, back in Inventor, can be updated based on differences that are found in the history-free model (two separate data models). My primary confusion with this concept is that if in fact the edits are possible in Inventor, then why do I need Fusion? Trying to create intelligent and properly structured history trees from history-free solids is nothing new, but Autodesk has made some progress in this area. I for one am a bit skeptical of this technology as there are just too many assumptions that the system must make to automatically create a useful tree structure, or edit an existing one. Not to mention getting a useful tree structure that would actually match my design intent.
Much of the confusion I see out there comes from the idea that somehow, some way, sometime, history-free modeling and history-based modeling will merge. Recently I watched someone draw two lines on a chart, one representing history-based modeling and one representing history-free modeling. At some point on the drawing the two lines merged into one. The merging of these two technologies is actually not possible. A CAD system is either recording the modeling steps or it is not. It is one or the other. The technologies can coexist, but it must be well understood how the resulting data will be used and managed.
Consider the intellectual property (data) that is created with a CAD tool. If the CAD tool is recording the modeling steps (history-based), the record (history-tree) is the critical IP. Without the history tree, the value of the model is considerably lower. If the CAD tool is not recording the modeling steps (history-free), the 3D model is the critical IP, history trees are of no value. Most any 3D model of reasonable quality can be considered valuable IP with history-free technology. That is not the case with history-based modeling.
While the technology to create history from non-history may improve a little, history-free modeling technology is continuing to improve - a lot. As history-free technology improves the value of the history tree declines. Eventually we may be wondering why we need a history tree, rather than trying to figure out how best to create, structure, modify and manage them.
This post probably does little to clear the confusion, but maybe we can work on that more in 2010.
Have a happy and successful new year!