Powering High-Speed Design

Clean, green, and capable of running for up to 100 miles on a single charge, Switch Vehicles' electric cars are anything but your typical form of transportation. So, it's fitting that the process by which they are created is equally extraordinary.

To develop the bodywork and instrumentation for its latest models, Switch turned to design consultant Max Sims - who, in turn, turned to Imagination Technologies' Series2 R2500 raytracing acceleration card and its Caustic Visualizer viewport plug-in for Maya.

Thanks to their ability to display accurate real-time reflections in the viewport, Sims can now create innovative designs without having to wait for test renders, working instead at the speed of thought.

Extraordinary cars for ordinary people

Based in Sebastopol, California, Switch has been converting vehicles to electric power since 1991. The company now hopes to make those two decades of experience available to the mass market with a new range of durable, flexible electric vehicles at a price "every American can afford."

Although it has only just shipped its fifth assembled vehicle (the products are also available in kit form for enthusiasts to build themselves), Switch aims to step up to manufacturing 50 cars a month - and for that, it needs a roof. At present, the cars are supplied as exoskeletons, with an exposed roll cage: in keeping with the company's green design ethos, but off-putting to many buyers.

To help create appropriate bodywork, the company called on Sims. A designer and teacher who runs his own consultancy firm, Technolution, Sims imports Switch's (Autodesk) AutoCAD data into Maya, where he designs surface coverings using a rather unusual tool set: the nCloth simulation system.

"A cloth covering is easy to prepare and assemble," he points out. "And if you think about it, it's not that unusual. All convertibles have cloth tops, right?"

Designed in real time

Maya's built-in tools enable Sims to simulate the physical properties of a range of real-world materials, from canvas to spandex. But to display the results accurately in the viewport, he relies on Caustic Visualizer, an interactive raytracing renderer capable of generating soft shadows, depth of field, and physically accurate reflections.

Even running on the CPU alone, Caustic Visualizer provides excellent performance. But used in conjunction with the R2500 raytracing acceleration card, near-real-time feedback becomes a true real-time modeling and rendering workflow.

"With the Caustic board, I can push and pull control points on a surface and see what happens to the reflections on those surfaces immediately," says Sims. "I don't have to wait for a render: I can literally do everything in real time."

Being able to preview reflections accurately is particularly important in automotive design, as Sims explains. "Reflections express the brand identity of the car," he says. "The way they accelerate and decelerate across surfaces is critical. If you're designing a sports car, you want a rapid change, to give a dynamic quality; if you're designing a luxury car, you want slower, more elegant changes."

Fabricated in hours

But when it comes to designing dashboard instrumentation, there is another, more pressing reason calculating reflections accurately: vehicle safety. Sims needs to ensure that the reflections of the instruments in the windshield never distract the driver from the road ahead.

To develop new instrument prototypes, Sims sketches outlines in Autodesk's SketchBook Designer, then imports the curves into Maya to use as the basis for 3D geometry. Most of the design work is done using subdivision surfaces, which enable Sims to make changes to the overall form quickly; then the model is converted to NURBS for export as an IGES file, ready for CNC machining.

"The design won't be Class A surfaces when I generate it from Maya, but it's good enough to machine a tenth-scale model," Sims explains.

Before the design can be fabricated, Sims needs to be sure that the reflections will fall in the right place. Once again, the R2500 card comes into its own here.

"Normally, you would have to take the model, adjust something, send it off to raytrace, then wait two minutes before discovering that you have to make another adjustment," he says. "With the Caustic board, I can change the angles of the instrument panel and windshield in real time."

Created in a single application

For Sims, the fact that Caustic Visualizer enables him to work solely in the Maya viewport is a major advantage over other rendering technologies.

"If I used a GPU-based renderer, I'd have to export the file to the other software package before it could do its magic," he says. "I wouldn't be able to iterate in the same way: I'd have keep stopping to reload the model and reassign the shaders."

Thanks to Caustic Visualizer's accurate, real-time, in-viewport feedback, Sims can create designs ready for prototyping in record time.

"If I were creating Class A surfaces, it would take longer, but as I'm sketching, as it were, I can do two designs before lunch and two after," he jokes.

A revolution in design workflow

For Switch Vehicles, the result is a series of innovative bodywork and instrument designs, the first of which should be in production in a matter of months. For the consumer, the result is a practical, affordable - and for the first time, weatherproof - electric car.

And for Sims, a designer with over 25 years' experience in the automotive and 3D industries, including stints at Opel, Renault and Alias Research, the result of using Caustic Visualizer in conjunction with the R2500 card is a revolutionary change in workflow.

"I can think so much faster," he says. "Being able to model and render at the same time is an amazing thing to me. I've been waiting for this for a quarter of a century."