Machine Design

The advantages of solid modeling in product development

Turning drab industrial products into eye-catching images can spruce up presentations and make complex operations understandable even to nontechnical viewers.

A few years ago when a surgical- equipment manufacturer on the East Coast conceived an idea for a new product, its marketing people would phone surgeons to ask if the idea was worth further development. When a positive response came back, one or two working prototypes were built out of stainless steel. But the necessarily small prototypes would cost upwards of $10,000 each because their many small details had to be machined under a microscope.

Looking for a less-expensive way to get ideas across to decision makers, company engineers discovered Ted Boardman, a training instructor specializing in rendering software called 3D Studio Max and Viz from Kinetix, San Rafael, Calif. These specialized packages (sometimes the features built into solid-modeling systems) add lifelike textures and colors to models. For example, they allow adding reflections to polished steel, wood grain to table tops, and shadows that add realism.

For about $600, the Portsmouth, N.H.- based instructor helped the equipment designers make a video of the proposed tools in action without ever making a tool. “Instead of demos under a microscope, they now project images of new equipment concepts onto a screen for several surgeons to critique at one time,” says Boardman.

One might think solid-modeling systems solved conceptualization problems long ago, but only somewhat because most modelers add only basic color shades to parts. Rendering software picks up where the modelers leave off, and that requires new thinking.

For instance, Boardman suggests beginning design concepts in the rendering software. “You won’t need to detail every nut or bolt just to get an idea across. And there are things you can do in the rendering software that are more difficult in solid modelers. For example, if you wanted to show coiled cable in a modeler, it’s quite difficult. But in the rendering software, it’s a snap. So it’s worth a closer look.”

Engineers are great at making things work, but not so hot at making them look good. And unlike Boardman’s surgeons, not everybody has the patience to peer into a microscope for a demo. “The effort is similar to that needed for photography,” says Boardman. “With 3D renderings, you can produce extremely good looking representations of products, explain the working concepts to investors, make more impressive presentations, and produce posters for trade shows, a place where looking sharper than a competitor can be the difference between sale or no sale,” he adds. Often for a fraction of the price of photographs and video you can concoct a prototype and generate models fit for brochures in a form most nontechnical people can understand.

The software takes a little training and experience before you can produce prize-winning images. To get potential users started a bit higher up the learning curve, we asked a range of engineers and designers who have won awards for their visual prowess for their guidelines in using the software. Their suggestions include:

Think like a photographer when setting up scenes. “The composition of the product and camera angle is critical,” says Charles Choi, president of Choi Design, Mt. Prospect, Ill. “First try several angles with simple shading,” he suggests. Uncomplicated scenes can render in less than a minute, so experiment with several viewing directions to see what looks best.

The most favorable angle will often be a perspective or camera view. “Then use lighting and shadows to bring out the 3D aspect of the model,” says Noah Kennedy, product manager for Autodesk’s Kinetix.

Because colors are critical, Edward Stamm, design manager with Panoramic Inc., Janesville, Wis., suggests calibrating your CAD screen to your color printer. “For example, print something out and hold it next to the screen. Then set the colors produced by the CRT to the print. This ensures that what you see is what you get, and you don’t have to make guesses for how an image really might turn out.”

Get training. It’s important because rendering involves different concepts from CAD. “And since it’s all fake, you’ll want to fake it good,” says Boardman. Users can quickly learn the basics of a package, but he suggests that getting comfortable with the software would take two to three months in a normal work environment. But intensive training and working through tutorials in a consistent manner 4 hr a day could cut that time in half.

Training becomes more important for mechanical designers because they tend to overlook the flexible modeling tools in rendering packages. “They’re already conversant with a CAD package, and they want the renderer to work the same way,” he says. “But it doesn’t. So they tend to use their CAD program to create models in cases where often they could create a much better and more efficient model in the rendering software.”

CAD differs from rendering software in that CAD lets users design as they go. “People running CAD systems already know their business,” says Boardman. But a presentation or video might require starting from scratch. “At first it’s not intuitive. New users have to learn about lighting, color, art, direction of characters such as mechanical parts — so there’s a lot more peripheral information to become conversant with in 3Dpresentation software.”

Practice the fundamental concepts of the software such as lighting, editing, and materials. “When you get a little experience under your belt, don’t be afraid to tweak the defaults in the material editor,” suggests Kinetix's Kennedy. “Use material effects such as shininess and bump maps to communicate shape and texture. The material editor in most packages lets users assign properties to surfaces so they look like steel, wood, or plastic.

Subtle differences can make a big difference. Even clear plastics require a little practice to get right. “We try to set the right clarity and color tone that plastics naturally show,” says Panoramic’s Stamm, “because different plastics call for different clarity settings. For example, vinyl throws a slight blue tint, PET produces a slight, frosty white tint, and some plastics cast gray,” he adds. A sample of the plastic in question can help fine-tune an image for greater realism.

The hardest tone to duplicate comes from flock materials. “It’s difficult to produce the flat impressions of flocking,” he says. “On fuzzy material like velvet, just make it as flat as possible.”

Use several light sources. One dominating flood light on the front can make the scene appear washed out. The contrast of light in a room from several directions casts several shadows as artificial light often does. The effect adds more realism to scenes.

“We usually set up two or three lights for each scene,” says Stamm. “One or two will be casting shadows, and a third will soften the shadows of the other two lights. This is so the shadows don’t build a contrast too great with the rest of the rendering. Otherwise, the shadows could become more interesting than the subject if they are overpowering,” he says.

Don’t skimp on hardware. Run the software on the fastest computer with the most RAM available, suggests Boardman. It’s a one-time fixed cost, along with the software. The learning curve tends to be the expensive part. The idea here is that complex images can take many minutes to complete when they include bit maps, ray tracing, many light sources, and complex shading. Each feature or highlight added to a scene adds to the rendering time.

“Be ready to limit some model detail,” says Charles Dennen, senior application engineer with Stonebridge Technologies Inc., Tulsa. The accompanying orange feedwater heater would ordinarily be stuffed with dozens of tubes, but the model was so large it overwhelmed their rendering software with excessive number-crunching times. As a concession, Dennen decided to omit some of the excess detail that did not detract from the image.

Good news here is that many of the rendering functions are easily made parallel so that a dual-processor computer that assists in analysis can also pare presentation tasks down to tolerable intervals.

Use animation to show the relationship between parts in an assembly. Basic animation features are more prevalent in recent solidmodeling systems, but most don’t match the motion possible with the add-on software. Rendering programs often allow taking an assembly apart to show line workers, for example, how a subassembly goes together. Single part models don’t need animation, but the features provide powerful capability for getting ideas across in ways that could help start a new company.

Engineers at large companies may not worry about helping with the next brochure. But when you must wear several hats, every talent counts. The point became clear to a manufacturer of sputtering machines. They came up with a radical design for a machine that occupies less space in a clean room and works with greater efficiencies, giving it a distinct advantage over traditional equipment that usually stretches for almost 100 ft. Exclusive Design Corp., Santa Clara, Calif., instead built its machine in a cylindrical fashion which minimizes the expensive clean room.

With the solid models of the design completed, they turned to 3D Studio Max to show prospective buyers how the machine works. The animation showed how discs would be manufactured and passed from station to station. Robots in several places picked up cylinders and placed them in the next operation. The animation of the sophisticated operation was good enough to persuade one diskdrive manufacturer to wait for the new design rather than another because they were able to see exactly how each operation would work and the advantages of each.

One advanced order on the $6 million machine was enough to recoup R&D costs. And the first sale jump-started the company into a positive cash flow. That’s not a bad day’s work for pretty pictures.

Say Hello to Your New Vocabulary

Rendering technology has roots in the photographic field so some of its terms are familiar. Other features and operations built on mathematical algorithms and computer technology require an explanation.

Antialiasing removes the jagged edges or stair steps that often appear in diagonal lines and curved edges.

Bit maps allow mapping each pixel to one bit in computer memory. A screen capture is a bit map image.

Bump maps, like textures, provide a way to make surfaces look rough, such as concrete or leather.

Gouraud shading provides more lifelike visual impressions than flat shading. It usually allows smooth color transitions from unlit to lit areas, and transparencies.

Phong shading provides more realistic visual information than the Gouraud method. Phong also allows shadows, textures, and highlights with little reflection or refraction.

Ray tracing provides realistic but compute-intensive images. It involves algorithms that trace a ray of light from the viewer’s eye to each pixel on screen.

Texture maps come in 2D and 3D versions. Two-dimensional versions are quite uniform. Their patterns are easy to spot. Three-dimensional methods, such as those that would produce a marble surface, are more complex.

© 2010 Penton Media, Inc.

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