2/1/1999 | 7 MINUTE READ

PC-based CAD for the Rest of Us

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For many automotive suppliers, Windows-based 3D CAD packages are now a reasonable alternative to high-end, Unix-based CAD systems. They run on inexpensive PCs, are full of features, interoperate with legacy data, and they've got the smarts to help designers out.


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Three-dimensional (3D) modeling is no longer an issue on a personal computer (PC).

But what has yet to be proved is whether the "personal" part of a PC also applies to improving personal productivity—both for "casual" and for "high-end" computer-aided design (CAD) users.

For many people—especially casual users—increasing personal CAD productivity is akin to making the CAD system "accessible." This means making it easy to use. It means ensuring that the hardware requirements—processor and random access memory—are affordable, if not already on the desktop. And it means providing a heckuva lot of functionality at bargain-basement prices.

A new generation of CAD packages announced this past fall do that and more. All run on Windows NT, the operating system from Microsoft Corp., and they feature such productivity enhancements as better associativity and interoperability capabilities, and artificial intelligence.

Revamping an Old Workhorse

Consider CATIA from IBM Corp. (Charlotte, NC). A lot has changed since CATIA was introduced 15 years ago. Computer hardware, operating systems, and programming techniques have all changed. Of particular note is this thing called Windows NT. "The mid-range is only NT for us," says Bill Cleary, marketing manager for North America, IBM Corp. His comment neatly sums up Windows NT's significance in the CAD market, especially given that CATIA has always been a high-end, Unix-based CAD system.

So along comes CATIA V5. Version 5 is not just an incremental version increase from CATIA V4. CATIA V5 is a brand spanking new CAD product. It has a new, object-oriented core modeler written in C++. Its architecture is based on OpenGL, OLE, CORBA, STEP, and other industry standards. It has Java elements. It is web enabled. And it has been written from the ground up to take advantage of Windows NT and Intel processors. "We could have taken CATIA V4 and ported it to Windows NT," muses Cleary, "but porting software doesn't work. It doesn't take advantage of the new compute environment."

All of this may come as a shock to CATIA V4 users. CATIA V4 runs on Unix and Motif; its user interface has words and commands. CATIA V5 is icons and windows; it conforms 100% to the Windows interface environment.

New product notwithstanding, IBM is not going to walk away from its CATIA V4 users—now numbering over 106,000 seats. Data files created in Windows NT-based V5 can be used in Unix-based V4, and vice versa. A browser in CATIA V5 lets users peruse a list of both CATIA V4 and V5 files. Simply clicking a mouse button on a CATIA V4 file will import that file into CATIA V5, including the file's history tree. Some CATIA add-on applications, such as a digital mockup tool for real-time walkthroughs, were originally written for CATIA V5, but implemented in CATIA V4. Granted, says Cleary, it will be a while before all of the almost 120 modules in CATIA V4 are rewritten for CATIA V5.

When CATIA V5 becomes available, scheduled for March 1999, it will include such modules to create associate drawings from 3D mechanical designs and assemblies, to produce photo-realistic images, to combine explicit rules with design intent, to perform finite element analysis pre-validation, and to create free-form shapes and deformations. The price had not been set at this writing.

Hiding CAD Behind the Windows Dressing

The price of CATIA V5 probably won't be too different than the $3,495 for another "from scratch" CAD system: Pro/Desktop from Parametric Technology Corp. (PTC, Waltham, MA). Like CATIA V5, Pro/Desktop is also a "Windows application," featuring icons, context-sensitive help, Wizards, and all the other things that people are comfortable with in more "casual-type"—read "consumer"—computer applications.

But beneath the Windows dressing, Pro/Desktop also tries to replace CAD-specific conventions with more familiar desktop conventions. Consider a common example: word processing, explains Wayne George, PTC's vice president of Strategic Marketing. There's not one environment for a sentence, another for a paragraph, and a third for a report. Instead, you type away on the keyboard and call the pearly prose whatever you want. If you want to break the pieces apart—create boilerplate sentences from a paragraph, for instance—you're welcome to do that, too.

Likewise in Pro/Desktop, there's no separate environment for part modeling or assembly modeling. Pro/Desktop completely buries the concept of assembly modeling into the underlying "assembly-centric" architecture. Designers design parts or assemblies in the "design environment," and the architecture manages all the relationships between these items automatically. Consequently, while creating parts in an assembly, the designer can use the geometry from mating parts directly to check tolerances and clearances.

Pro/Desktop eliminated other CAD barriers. Designers can reuse features as components. It allows multiple solid bodies in the same part file and multiple profiles in the same sketch. Plus, Pro/Desktop eschews having an icon for every different line type. Instead, there's one icon for lines, arcs, and splines. A designer can draw a line and later decide to make it a spline. The designer merely highlights the line and then clicks the right mouse button to convert it to spline. The solid model automatically updates to reflect that new shape. In other CAD systems, such a change would require deleting the line and starting over.

Pro/Desktop can be a standalone CAD system as well as an entry point to PTC's Pro/Engineer product family. To make the two product families interoperable, Pro/Desktop includes PTC's associative topology bus (ATB). ATB lets systems share geometry and topology in an associative manner, without requiring users to have the originating CAD application on their desktop systems. So, an engineer can design a fixture in Pro/Engineer, drag-and-drop it into Pro/Desktop, and then continue designing in Pro/Desktop. Later, if the Pro/Engineer part changes, the design in Pro/Desktop will automatically be updated.

CoCreate Software Inc. (Fort Collins, CO) takes the compatibility featured in CATIA and the interoperability featured in Pro/Desktop a step further. In its SolidDesigner V6, Dynamic Modeling Open Extensions (DMOX) technology "adds intelligence into an imported 3D model," says Geoff Hedges, product marketing manager for CoCreate. Doing this lets designers reuse and modify 3D legacy and history-based models created in non-CoCreate CAD systems. In operation, when importing models using STEP or IGES data-exchange standards, DMOX automatically identifies such model characteristics as bosses, pockets, blends, and logical geometric relationships such as tangency conditions. "The benefits of dynamic modeling can be applied equally to native SolidDesigner models and to imported legacy models," continues Hedges.

Adding Intelligence to the CAD Interface


All of the CAD vendors are adding some type of artificial intelligence into their CAD systems. For instance, look at the STREAM technology in version six of Solid Edge from Unigraphics Solutions (Maryland Heights, MO). STREAM is a proprietary technology that provides quite the helping hand to CAD users. "Until recently, most CAD packages were only compared on a feature/function basis, but features and functionality do not necessarily translate into increased engineering productivity," says Bill McClure, director of the Solid Edge line of business at Unigraphics Solutions. "STREAM takes user interaction and decision management into account to boost design productivity."

STREAM addresses designer productivity in three ways:

Inference logic. STREAM monitors the state of the software, including current inputs such as commands and mouse movements. Based on that, Solid Edge infers what the user is trying to do. Then it does it. (The user can always change the software's action.) For example, if the designer sketches an arc off the end of a line, that is, the mouse moves somewhat tangent from the end of the line, Solid Edge will automatically draw an arc. If the mouse movement is somewhat perpendicular to the line, Solid Edge will automatically draw a perpendicular line in the direction the mouse moves. Moreover, the system captures that design intent; that arc or line will always remain tangent or perpendicular regardless of other design changes.

Decision management. Instead of displaying large quantities of data and numerous options, Solid Edge displays only the relevant data and options based on the current state of the software. For instance, the Sheet Metal environment within Solid Edge has a taskbar that displays parameter options sequentially and as they apply to the item being designed, such as where new material is added to existing material, datum locations for dimensional references, and corner relief where bends meet.

Process-specific features. To minimize user interaction, Solid Edge uses model features that represent forms and functions unique to an industry. Again using the sheet metal example, the designer can create a sheet metal flange by pointing to a line and dragging it. The CAD system will then automatically create the thickness, the bend radius, and other features.

Solid Edge should be shipping by now and selling for $4,995.

And the Winner Is...

Inexpensive and relatively simple, but sophisticated, CAD systems fill two niches. One is at the large company that wants to capture modeling concepts, but doesn't need or want to pay for additional high-end CAD seats. Along those lines is an interesting statistic from an IBM spokesperson: More than half of the CATIA customers have only three seats.

The other niche is in the design departments of suppliers at the second tier and below. These relatively small companies have gotten by with shrink-wrapped 2D CAD packages, but they are increasingly tackling some fairly complex designs, manufacturing processes, and products that could benefit from full-function, in-context, digital solid mockups. These suppliers can't afford the Unix-based CAD machines preferred by the large automotive companies, but they can afford the Windows-based systems.

Regardless of the niche, these next-generation, PC-based CAD systems make winners out of all designers.


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