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Look, but Don't Touch
18 Feb, 2010 By: Nancy Spurling JohnsonThe fantasies of sci-fi become real as digital holograms bring virtually any 3D data to life.
Editor's note: This article was originally published in the Winter 2010 edition of Cadalyst magazine.
When Elvis was beamed onto the stage of "American Idol" in 2007 to sing a duet with Celine Dion, and when correspondent Jessica Yellin popped onto the New York City set of CNN on election night 2008 — even though she was on assignment in Chicago — holography created quite a stir. Although some debated whether those were true examples of the technology, there's no question they got our attention.
Today, holography is getting attention in the design world as well, as a striking new way to present a 3D model. With what is known as a digital hologram, you're able to walk around the model — whether it be a skyscraper in its downtown setting, a topographic map, or even a life-size concept car — and view it from every angle. The model you see is fully detailed and highly accurate — but if you reach out to touch it, your hand will slice through the air.
When people see a digital hologram for the first time, the reaction is, "What is it?" and "How did you do it?" says Jay Mezher, manager of design visualization in the Seattle office of Parsons Brinkerhoff. The firm has used the technology to create infrastructure models that show proposed designs of highways and tunnels, and even to create an urban scale hologram depicting the city of Seattle. "This has added another amazing tool to the virtual design and construction [VDC] approach we take with our projects," he says. "We're intrigued by the ability to display a three-dimensional hologram instead of a projected 2D image."
These 3D models that you cannot touch are created from virtually any 3D data, printed on a flat surface, and viewable when light strikes them at a certain angle. Digital holograms can be used as a permanent display, or tiles can be disassembled and compactly stored or easily transported to another location for review. They are being used for applications ranging from design showrooms to overseas military operations.
How It Works
In contrast to analog holograms, which are exact 1-to-1 reproductions of existing objects, digital holograms are completely scalable and based on 3D data such as CAD models, laser scans, or satellite imagery. They can be created from other digital data as well, such as video footage or a series of photographs. Based on proprietary technology using lasers, optics, and image processing, digital holograms are printed by machine, pixel by pixel, to create what is effectively a compilation of thousands of high-fidelity rendered still images.
At Zebra Imaging, a developer of digital hologram technology based in Austin, Texas, color and monochrome holograms are printed on photopolymer film, usually in two to three hours' machine time depending on a model's complexity. The film is applied to acrylic tiles for display and easy portability. The result is a hologram that has a wide viewing angle and a large depth volume that appears to extend above and below the display surface, and that is full parallax, meaning the 3D depiction is correct from every vantage point.
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View Holographics, a provider of analog and digital holographic services in the United Kingdom, uses red, green, and blue lasers at specific frequencies to create full-color digital holograms. An image is created within a photographic holographic emulsion coated on a sheet of glass. A 1-square-meter hologram requires approximately 10 hours to print, plus a few more hours to develop.
In their finished form, digital holograms can be displayed vertically on a wall or a stand, or horizontally on a table or a floor. The 3D holographic effect comes to life in sunlight or when an artificial light shines on the surface at a specific angle. No special glasses are necessary.
Multiple people can view a digital hologram from all vantage points around a static display; the model
appears to change according to each viewer's perspective, or the display itself can rotate. Some digital holograms convey a single representation of a model. Others could show a building design with and without a roof cutaway, depending on the viewing angle, or the progression of a product redesign from old to new.
Short 3D animations can be made by running several holograms in succession. As another option, Zebra Imaging can create transparent overlays for holograms to display annotations, updates, or other data or to show existing project conditions juxtaposed with proposed alternatives. "We're motivated by the potential of the technology," says Mezher, a Zebra Imaging client. "The possibilities are endless."
3D digital holograms can facilitate design review and collaboration in much the same way as a physical prototype, as shown in this visualization. Image courtesy of Zebra Imaging.
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About the Author: Nancy Spurling Johnson
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