7/1/2001 | 6 MINUTE READ

Fast and Easy for MID-RANGE CAD

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Imagine 3D designs displayed at the speed scenery flashes by in your kid's computer game. Also imagine easy to use—really easy—solid modeling. Imagine no longer. Here are two real systems that meet the imagination.


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Seeing is believing, especially in engineering environments involving high-end products, rapid prototyping, and complex surface renderings. So it's "nice" when you can see a design in an everyday setting. Even nicer is to see that visualization fast, whether as a still-frame rendering or an animation. Being able to create the designs fast is better still.

You can do all of that in today's high-end computer-aided design (CAD) for some pretty high-end prices. But take a look at what you can get in mid-range CAD: inexpensive modelers that are blazingly fast, chock full of design functions, and incredibly easy to use.

CAD can be all fun and games
Merlin 3D from Digital Immersion Software Corporation (Sudbury, ON, Canada) generates photorealistic visualizations—fast. Real-time fast. And it only costs $595. This standalone, real-time 3D modeler for desktop personal computers (PCs) uses common 3D graphics cards to generate scenes involving more than 1,000,000 polygons, and textures, lights, and even fog—all at acceptable speeds. You can dynamically manipulate objects and navigate through scenes with no loss in depth perception or texture placement. You can position an unlimited number of lights in a scene, seeing in real time how the color, position, and strength of those lights affect the models. And you can record animations by strategically placing multiple virtual cameras throughout the visualization.

Behind the scenes, so to speak, is Merlin 3D's heavy reliance on Microsoft DirectX and Direct3D. These are the same application programming interfaces (APIs) that drive all those high-quality games you read about (or play yourself) such as Unreal Tournament and Quake III, as well as the curvaceous heroine in Tomb Raider. The fact is, the gaming world has grown exponentially faster than the world of 3D engineering design. And that's true technologically as well as probably financially.

Some technical details. DirectX lets programmers write multimedia applications for any Windows PC. (Almost. Up to DirectX version 3 can run on Windows NT. DirectX version 8 is now available for Windows 95/98/2000.) DirectX applications exploit the microprocessor's capabilities for faster performance. The API also lets graphics cards vendors create specialized drivers to fully exercise the graphics chip sets on their cards. One of the DirectX APIs is Direct3D, which is tailored for drawing the 3D scenes in complex graphics and game programs.

"Our programmers have taken the DirectX gaming engine and manipulated it into a program that you can actually interact with," explains Tyler Campbell, Digital Immersion's sales manager. This is in contrast to the typical application of DirectX, which is to use it as "just" a game engine for one-way interaction that you control but can't interact with. In this case, the interaction suitable for engineering would be the ability to create and manipulate objects. And that is exactly what Merlin 3D provides.

Using Merlin 3D is easy. Its commands aren't geek-speak. Want a cube, sphere, cone, or cylinder? Click on cube, sphere, cone, or cylinder. Boom, you've got that shape. Usually, you'll just import a model using any one of a variety of file formats, including DRAWING, DXF, 3ds, PRJ, SAT, and STEP, and go from there.

You can use Boolean functions to create custom objects by adding, subtracting, or intersecting two objects together. You can interactively deform objects using animated modifiers such as stretch, scale, bend, twist, and bulge. Or, says Campbell, "you can add geometry in all the right places" with Merlin 3D's subdivision surfaces tool. Basically, this tool adds polygons to whatever model you've outlined, thereby smoothing out the "jaggies." Another tool, inverse kinematics, lets you apply motion to the objects you've designed.

Merlin 3D's texture mapping is also interactive. There is even a multi-layered paint shader that simulates clear-coat automotive paints, lacquered woods, and more. Plus, you can adjust the texture mapping type (for instance, box, sheet, spherical, and chrome), and then visually customize scale, rotation, and position coordinates.

CAD can be easy
If, however, your design needs point more toward heavy-duty solid modeling, think about thinkdesign 6.0 from think3 (Santa Clara, CA). As its name implies, this CAD package lets you think more about design than the process of designing.

Based on a proprietary kernel, thinkdesign doesn't distinguish between solids, surfaces, wireframes (splines), or 2D geometries. These design modes all function in one, integrated design environment. This lets you bounce back and forth between, say, 2D and 3D, without intermediate data translations. Moreover, thinkdesign is a non-manifold modeler. It lets you work on solids that are not completely solid, such as defining a hole through a cube defined by three walls.

Also in thinkdesign, surface modeling tools and solid modeling tools are indistinguishable from one another. Moreover, the most commonly used surfacing tools are captured in the model history and are fully associative to their base curve definition. As a result, you now have a fully associative curve/surface/solid modeling environment; a change in any one environment affects the other two.

So much for basics. Now for the differentiators that make thinkdesign solid modeling truly easy. First, there's the user interface (UI). Just about every field in the conventional, large, multi-field, context-sensitive dialog boxes found in most Windows applications today has been broken up into its own tiny, context-sensitive "mini-dialogs." These mini-dialogs, which pop up next to their associated geometry element, display the relevant parameter of that geometry. Consequently, there's an immediate connection between the design parameters being entered and the graphical result of that entry.

Another element of the UI is the selection list browser, which "floats" in the design space to give you an unobstructed view of your design. This browser acts as both history list and design Wizard. Using colored icons (a green bullet with a check mark, for instance), the browser indicates whether specific design elements are mandatory and satisfied. It can also indicate optional elements that you can ignore or use as a prompt to guide you through the design process.

You can even talk to thinkdesign. "Speech recognition is a beautiful user interface," says Joe Costello, think3's chairman and CEO, "because you're controlling the system with your voice and keeping your attention, your eye-hand coordination, completely on the drawing."

Speech recognition has another benefit as well: It "flattens" out the whole command set of the system such that users can get to desired commands quickly.

thinkdesign's second major differ-entiator is a feature called "global shape modeling" (GSM). GSM lets you warp existing 3D geometry while honoring conditions you set up. To use it, grab the drag handles on a geometry to tell thinkdesign where you're starting—what part of the existing design is to be modified—and where you want the design to wind up. GSM then deforms the 3D space and associated surfaces accordingly while maintaining the integrity of the model, its internal continuity, and the continuity (read:smoothness) between surfaces. For example, you can modify an automotive quarter panel by moving the wheel well forward and upward, while keeping the panel's bolt locations fixed. You can see this modification at point and click speed.

"You can make all kinds of variations to you heart's content," says Costello, such as bend, twist, stretch, wiggle, and tilt. "GSM figures out how all the underlying mechanical design elements fit together. And it doesn't matter whether you're working with solid models, surfaces, wire frames, or imported geometry."

A third differentiator toward ease-of-use is Smart Objects. These are pre- and user-defined design elements that go way beyond what in other CAD systems are called "user-defined features" or "macros." Smart objects capture "design intent," they are parametrically defined, and they adapt to different topologies.

Unlike macros, which are well-suited for performing exactly the same design step(s) over and over, Smart Objects can blast through a lot of the detailed grudge design work that is repetitive, but not perfectly repetitive.

In operation, drag and drop the relevant Smart Object onto your design, point to the parameter to be adjusted, input a new value, and instantly the newly inserted element has the dimensions and geometric relationships that your design requires. For example, a simple post from a Smart Object library of plastic parts will "know" how to automatically orient itself perpendicular to the face of a solid model when dragged into that model. Moreover, it will know to automatically create a fillet at the joint between the post and the face.

thinkdesign 6.0 costs $1,995 annually, and comes with direct translators for Catia and the Parasolids kernel, as well as an IGES translator.

Fast and easy. Inexpensive. Productive. Shouldn't all software packages be like that?


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