By Deelip Menezes
Deelip Menezes is the owner of SYCODE(Goa, India)
It’s often frustrating to work with multiple CAD programs because of the inherent proprietary file formats many CAD software vendors use. Often, you cannot transfer solid models from one parametric solid modeling system to another without losing parametric information. In addition, you often cannot even save to an earlier version of the software you are using. Thus, interoperability between two parametric modeling systems requires the use of neutral file formats such as IGES, STEP, and SAT where the solid models come in as dumb solids, making it impossible to edit their parametric features. CAD vendors have yet to reach a solution to this problem, and none seems to be coming in the near future.
New modeling techniques help eliminate the problems of incompatibility among CAD programs. To change the radius of a fillet, for example, the newer programs let you select the curved face that makes up the fillet and pull it to increase or decrease the radius.
However, a new modeling technique, something we at SYCODE refer to as CAD 2.0, may help. It is a modeling technique employed by SpaceClaim Professional 2007, a CAD software program developed by SpaceClaim Corp. (www.spaceclaim.com). How can a modeling technique solve a data interoperability problem? Actually it’s quite simple.
The modeling technique takes a dumb solid model and recognizes its features. Thereafter, intuitive editing tools let you handle parametric modeling without the hassle of a feature tree. For
example, if you want to change the radius of a fillet, select the curved face that makes up the fillet and pull it to increase or decrease the radius. Doing the same thing in a conventional parametric modeler would be impossible because the fillet face is as dumb as the original solid.
Similarly, if you want to increase the diameter of a hole, simply select the cylindrical face that describes the hole and pull it outwards. Or if you want to move the hole to a different location, select the cylindrical face and move it.
With this modeling technique, if you can do parametric modeling on a dumb solid, then an IGES, STEP or SAT file is as good as the original proprietary file created by a parametric modeler. Any solid modeling system should be able to import and export to one or all of these neutral formats.
To increase the diameter of a hole, CAD neutral programs let you simply select the cylindrical face that describes the hole and pull it outwards. To change its location, you select the cylindrical face and move it.
In such a world, proprietary formats will not matter much. Although data exchange across different systems occurs through neutral formats alone, in the new paradigm, sending and receiving systems will recognize each other’s parametric data because both modeling systems recognize the features automatically when loading the models. For example, say you create a box in one CAD 2.0 system, apply a fillet and save the model as a SAT file. Then you import the SAT file into another CAD 2.0 system, change the fillet radius, add a hole feature, and save it back as a SAT file. Thereafter you import this modified SAT file back in the first CAD 2.0 system and you will be able to edit the hole and fillet as if they both were created in the first system. Your model has actually done a round trip but it seems as if it was modeled entirely in the first CAD 2.0 system.
In recent years, modeling has changed to emphasize ease, speed, and efficiency. However, you can become so entangled in issues like parametrics, constraints, file formats, software versions and upgrades, that it is easy to lose focus on the current project. A CAD 2.0 system can help you create a 3D watertight solid model that can be easily modified by others using any CAD software at any version level, including future versions.
A CAD 2.0 type system helps you work on design, not on bookkeeping parameters, relationships and constraints in a feature tree; or wondering whether another engineer will be able to modify or view the model in another program, including earlier versions.
Moreover, proprietary file formats will no longer tie you down. You can work in any other CAD 2.0 system at any time and directly work with your models from day one. You do not need to worry about what software others are using.
As new versions of conventional parametric modeling programs roll out, they will be compatible with these new ormats. They will automatically recognize model features and update the feature tree. Then, they will effectively become “CAD 2.0” systems. Their proprietary formats will lose relevance, apart from storing non-geometric data such as textures, annotations, and other information.
It is unlikely that conventional parametric modeling systems will not evolve. You will be able to switch to a CAD 2.0 system quickly by saving your models in a neutral format and work with them directly in the CAD 2.0 system.
Deelip Menezes is the owner of SYCODE (www.sycode.com) based in Goa, India. He specializes in developing plug-ins for many CAD systems including AutoCAD, Autodesk Inventor, Autodesk VIZ, 3ds Max, SolidWorks, Solid Edge, SpaceClaim, Alibre Design, Rhinoceros and IntelliCAD.
Filed Under: 3D CAD, Software