July 21, 2000
UW scientist leads the way in computer graphics research by melding traditional art and high tech
Where art and technology meet, you’ll find David Salesin.
The University of Washington associate professor of Computer Science & Engineering and senior researcher at Microsoft Corp. has been expanding what’s possible at that juncture for more than a decade, bringing techniques from the fine arts to the computer screen. His goal? To visually combine the new and the old in ways that make the virtual world more flexible and understandable.
“Sometimes photos don’t do an adequate job of explaining things,” Salesin said. “I thought that by using some of the techniques artists use, one could bring subtleties into play that are just not part of a photorealistic image.”
Salesin’s resulting computer programs make it easier for users to create detailed pen-and-ink drawings, which can better illustrate concepts than a photo, and accurately “paint” in watercolors on their computers. He has also pioneered research into tiling of complex images, algorithmically created floral design, manipulating plant models with botanical accuracy, and putting a face on the e-mail chat room experience with animated characters.
This week, Salesin will be honored for his work in non-photorealistic rendering with the ACM Computer Graphics Achievement Award at the SIGGRAPH 2000 conference, the Association of Computing Machinery’s international computer graphics meeting that attracts more than 50,000 participants from academia and industry.
The SIGGRAPH (Special Interest Group on GRAPHics) conference runs Sunday through July 28 in New Orleans.
The award is well deserved, according to Ed Catmull, chairman of the SIGGRAPH award committee and co-founder of Pixar Animation Studios.
“Salesin’s work on computer-generated pen-and-ink illustrations and subsequently computer-generated watercolors is considered a landmark in this emerging field,” Catmull said. “For the past six years, his publications in this area have been extremely significant and influential.”
Added UW Computer Science and Engineering Department Chairman Ed Lazowska: “He’s clearly the leading figure in computer graphics in his generation.”
In merging art with computer technology, Salesin and his colleagues have to delve into the artist’s psyche.
“When you’re dealing in this domain, things often are not so clear. Generally, the artists themselves can’t fully describe what they’re doing,” he said. “Reverse engineering what the artists are doing, then trying to express it algorithmically, is a fascinating process.”
To digitally capture the essence of watercolors, for example, Salesin and his colleagues interviewed artists about the processes they use. They also talked with chemists who make the paints. The challenge was in recreating the complex processes that occur when pigment, water and paper interact under the influence of the artist’s brush, processes that give watercolor paintings their unique vibrancy and richness.
Salesin and his group developed a model for watercolor’s two essential behaviors: physical behavior, or how watercolor flows, and optical behavior, or how watercolor diffuses on paper. Using Salesin’s program, each painting is represented as a series of washes over a sheet of rough paper, with each wash containing pigments in varying quantities over different parts of the image. Those quantities are stored in data structures called “glazes.” The program mathematically accounts for other effects, such as paper texture, fluid flow and edge darkening.
Computer artists can manipulate the parameters of each glaze, pick the color of the pigments and the size of their brush. There is also an option to “watercolorize” an existing image by setting parameters and letting the computer take over.
In bringing pen-and-ink drawings into the computer arena, Salesin said he wanted to make the time-intensive work, normally reserved for highly skilled craftsmen, more widely available. Illustrations, rather than photos, are widely used in technical literature such as automotive manuals and medical atlases because of their ability to emphasize selected elements of complex structures.
“The idea is to let the computer do the tedious part of the work and let the artist guide it,” he said. “We also wanted to give non-artists a way to use these kinds of illustrations in a publication. And it would also be useful to display an image in any scale, after the fact.”
Salesin and his collaborators developed techniques that allow computers to find the balance between texture and tone, giving illustrations needed detail without making them too dark. With the program, PC artists don’t have to pen every line – they can select a texture, specify the tone and direction of the strokes, then let the computer do the work.
Salesin has become a regular contributor to SIGGRAPH, having published 29 papers at the conference, considered the most prestigious of places to publish on computer graphics. He also holds the record for the most papers published at the meeting in one year – eight papers, in 1996.
His five SIGGRAPH papers this year include a paper on “video textures,” a new sort of medium which Salesin describes as lying somewhere between a photograph and video. Essentially, the computer takes frames of a video clip and continuously rearranges them to form a seamless whole.
“Video textures can be used wherever digital photos are currently used in order to show explicit but non-repeating motion,” he said. “Say you’re running a travel agency and have a Web site. Rather than showing a static photo of some palm trees, your Web site could show the palm trees continuously swaying in the breeze. Video textures can also be used to shorten or lengthen a video sequence without it being noticeable.”
Salesin admits to being embarrassed by all the attention his work receives. For him, he says, it’s just a matter of doing what comes naturally.
“Computer graphics has traditionally been about taking ideas from other fields, like physics and the other sciences, and applying them in a computing environment,” he said. “I can do physics, but I came to realize that’s not my love. My love is art. I thought it would be just as valuable to take ideas from art and apply them to the computer.”
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For more information, contact Salesin at (206) 685-1227, (425) 705-3405 or salesin@cs.washington.edu. Salesin is scheduled to be at SIGGRAPH July 22-28. During that time, messages can be left for him at the Sheraton New Orleans Hotel, (504) 525-2500. A high-resolution photo of Salesin is available on the Web at www.washington.edu/newsroom/news/images/salesin.jpg.
Abstracts of Salesin’s recent publications with full-text links can be found on the Web at www.cs.washington.edu/research/salesin/salesin-abstracts.html.
