Hannover, 02. April 1995
Virtual technology has entered the real world arena. In the Daimler-Benz Virtual Reality Laboratory, real design models are being transposed into virtual reality using three-dimensional scanners. Future products can be viewed in 3-D on the computer screen long before they go into production. As a consequence, changes in a product's appearance can be made quickly and at an early stage.In the future, great significance will be attached to this "virtual prototyping" technique. Not only will it speed up development and production, but it will also reduce costs. The days in which wooden models first had to be constructed over a period of several weeks are coming to an end. A concrete example of the use of virtual reality in the Daimler-Benz group is provided by the research project "Spatial Perception in Vehicle Interiors," a project in which special emphasis is placed on psychological factors. How is the interior of a Mercedes perceived? What are the deciding factors involved? Is it the color, the design, or the altered geometry of the vehicle which most influences driver perception? The "test drivers" are expected to help answer the researchers' questions by comparing variations of different models.
The tests always run along much the same lines. The "guinea pig" is seated in the driver's seat. A steering wheel juts out from a mock instrument panel. Nothing else resembling a Mercedes is to be seen. Yet, no sooner does the would-be-driver don the stereoscopic display helmet than he is immersed in a man-made, 3-D world of virtual reality. In whatever direction the test person turns his head, he sees the interior of a Mercedes. Though the various perceived images are computer generated, the blue upholstered seats with soft white stripes, the streamlined, leather-covered instrument panel, and the rear seat bench with its built-in headrests all look deceptively real. The effect is achieved by sending stereoscopic images from a computer in rapid succession to the display screens in the monitor helmet. The computer follows every turn of the test person's head, mimicking reality by instantaneously sending corresponding images to the helmet. The result is a truly convincing impression of a three-dimensional scene.Simply pressing a button a few times causes the computer to change the color of the initially blue car, first to red, then to beige. Color, however, is not the only facet which can be changed in the blink of an eye. At the touch of a button the two roof supports on either side of the windshield can be slightly canted to optically alter the size of the passenger compartment. How these changes are seen by the test person, or whether they are noticed at all, is something which the researchers at Daimler are attempting to determine.
Using a special questionnaire with a scale of one to seven, the test person records and evaluates his impressions. Is the vehicle interior practical or unpractical, too spacious or too cramped, soothing or annoying? In all, a total of 26 questions must be answered. And the researchers aren't the only ones anxiously awaiting the results. The vehicle design team at Mercedes-Benz also hopes to be in possession of the preliminary data by the end of the year. The Mercedes team hopes that the findings will help it determine what sort of criteria the consumer uses when judging the Mercedes and how cars of the future should be built.When the project began three years ago, the Berlin researchers originally planned to use real vehicles in their tests. It soon became obvious, however, that changing from one vehicle to another caused severe distortions in the test results. The change-over simply took too long and hampered the direct comparison between the different models. Fortunately, as if on cue, the promising world of virtual reality came to the rescue of the psychologists: instead of metal, their Mercedes would from now on consist of bits and bytes. The artificial, computer-generated Mercedes made it possible to simulate the various models virtually in the head-mounted display simply by pressing a button.
The layout for the virtual Mercedes was supplied by the design engineers. Every component, from the body to the famous star on the hood, lies dormant in the computer as a 3-D object. From these building blocks, the researchers wanted to create a three-dimensional Mercedes in which a person can sit just as if he were ensconced in a real car. Since the Daimler-Benz psychologists aren't computer specialists themselves, they sought the support of "Art + Com," the Berlin-based research and development center for computer-aided representation and design. It was here that the constructional data were transformed into moving images.
In its computerized form, a curved surface such as the instrument panel consists of a myriad of triangular and other polygonal surfaces which wrap around curved and angular objects like a net. The more intricate the shape of the object, the more puzzle-piece-like polygons are needed to produce the computer image. No less than a thousand polygonal shapes are needed to make up the Mercedes star emblem alone. The accuracy of the computerized images must be of the order of one quarter of a millimeter to ensure that the objects can be machine-tooled later.
Such resolution would, of course, be too fine for practical virtual renderings. The more polygonal surfaces an image has, the more time the computer requires to process it. To achieve a realistic motion-picture effect however, the computer must process 25 to 30 images per second. In order to perform at that rate, the Berlin research laboratory's graphics computer is limited to no more than 30,000 polygons per image. The constructional data, therefore, had to first be painstakingly trimmed of any superfluities. All polygons which weren't crucial for producing the desired optical effect were removed from the program, in part manually. The remainder were then refined into nine possible Mercedes variants: three cars, each of which can take on three different color schemes.
And this is just the start as far as the Berlin vehicle design psychologists are concerned. The virtual-reality designers are already making plans for the future. Perhaps in the course of the next ten years, it will be possible for a Mercedes customer to "virtually" sit in his new car, experiencing and examining the various options - while the deal is still going on.
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© 1995 Daimler-Benz