Papers   Conference 8-13 August 1999   Los Angeles Convention Center Los Angeles, California USA   "When I set out to highlight the best SIGGRAPH 99 Papers, reviewing all 50+ accepted submissions, I found it far more daunting than originally thought -- there are so many outstanding papers! Representative works evoke a near future world where your TV is going to have a camera on top of it to place you in the scene [see Creating a Live Broadcast from a Virtual Environment]. There's a little blue wall that you walk into, and your face is scanned and mapped onto Tom Hanks' face so that you are now Forrest Gump speaking to President Kennedy [A Morphable Model for the Synthesis of 3D Faces]. Imagine the possibilities for education. Picture a TV show where kids are virtually transported into a common environment, where they participate in a sketching/modeling class using the Teddy system, a wonderfully intuitive interface to enhance and nourish natural creativity and talent.   "Computer graphics remains kinetic. Despite its rapid maturing -- evident from the styling of the car you drive to the visual effects on every corner movie screen we continue to see enormous advances. I can't pick highlights. SIGGRAPH Papers are all highlights. I can only offer a sampling of the best research contributions to computer graphics and interactive techniques."   Alyn P. Rockwood SIGGRAPH 99 Papers Chair,   Software Systems Hardware speeds traditionally increase more than an order of magnitude each decade, but improvements in computational methods have averaged more than ten times this rate of advancement. A prime example of this trend is the research presented in the paper entitled Stable Fluids that presents animation tools, previously thought to be unachievable, to model fluid-like flow behavior, including interaction of flows with objects, at speeds approaching real-time simulation. Or Graphical Modeling and Animation of Brittle Fracture that simulates realistic fracture propagation in breaking objects from dropped bowls to demolished walls -- one of three Impact Papers selected for SIGGRAPH 99. Along with such pioneering achievements, we continue to find newer and better ways to solve familiar graphics problems, from fundamental algorithms to hardware tools that continue to advance graphics accelerators. For the first time with The VolumePro Real-Time Ray-Casting System, we now have commercially available (3D) volume rendering in hardware. In software rendering, there are continuing strides in photorealism, but we're also seeing new horizons, especially in the area of non-photorealism or "imagination-based rendering." For example, the Dr. Seuss-style effect presented in Art-Based Rendering of Fur, Grass, and Trees.   Lighting & Visual Cognition LCIS: A Boundary Hierarchy for Detail-Preserving Contrast Reduction is working on a problem that is 30 years old. One cannot simulate powerful light contrasts like the reflection of sunlight from a car windshield using the limited candle power of a computer monitor. These authors demonstrate a new approach that accounts for visual perception to create a virtual optics that takes advantage of the way we perceive (i.e., you have to fake it to make it look real). Graphics and visual cognition are interrelated. This is one of the great frontiers of science.   Interactive Techniques We're continuing to see the emergence of interfaces between humans and computers that are contained in devices -- the monitor is actually antiquated. Now we have to rethink graphics as evidenced with papers like Emancipated Pixels: Real-World Graphics in the Luminous Room and Balancing Fusion, Image Depth, and Distortion in Stereoscopic Head-Tracked Displays where we are actually working with the human anatomy, things like vision and how the mind interprets visual cues. With a simple physical change in how we visualize our world, all the foundations of computer graphics aimed at the desktop may need to be changed.   Chaos & Intelligence in Software The paper entitled Cognitive Modeling: Knowledge, Reasoning, and Planning for Intelligent Characters is representative of a seminal technology. How would you plan a creation? Dynamical systems are chaotic, unpredictable. When we are dealing with chaos, we need some method for natural selection and propagation -- the only way we can handle the unpredictability of a complex system. These intelligent characters can actually surpass their training. So we see confirmation of the real world in their emergent behavior. In this way, paradoxes can be modeled that cannot be understood with Newtonian laws.   Following are highlights from SIGGRAPH 99 Papers, including Impact Papers selected for the overall impact the research is expected to make in the field of computer graphics and interactive techniques:   IMPACT PAPER: Graphical Modeling and Animation of Brittle Fracture James F. O'Brien & Jessica K. Hodgins Georgia Institute of Technology   The use of simulated motion in several commercial animations in 1998 demonstrated that passive simulations are a powerful and perhaps even essential technique. The authors' approach is demonstrated through animations of breaking bowls, cracking walls, and objects that fracture when they collide. By varying the shape of the objects, the material properties, and the initial conditions of the simulations, strikingly different effects are created ranging from a wall that shatters when it is hit by a wrecking ball to a bowl that breaks in two when it is dropped on edge.   IMPACT PAPER: A Morphable Model for the Synthesis of 3D Faces Volker Blanz & Thomas Vetter Max Planck Institute for Biological Cybernetics   A new technique for modeling textured 3D faces that can either be generated automatically from one or more photographs, or modeled directly through an intuitive user interface is introduced. Face manipulations according to complex parameters such as gender, fullness of a face, or distinctiveness also are demonstrated.   IMPACT PAPER: Teddy: A Sketching Interface for 3D Freeform Design Takeo Igarashi & Hidehiko Tanaka University of Tokyo   Satoshi Matsuoka Tokyo Institute of Technology   A sketching interface to quickly and easily design freeform models such as stuffed animals and other rotund objects is presented. The user draws several 2D freeform strokes interactively on the screen, and the system automatically constructs plausible 3D polygonal surfaces. An informal user study showed that a first-time user masters the operations within 10 minutes, and can construct interesting 3D models within minutes.   Art-Based Rendering of Fur, Grass, and Trees Michael Kowalski, Lee Markosian, J. D. Northrup & John Hughes Brown University   Lubomir Bourdev SGI   Ronen Barzel Pixar Animation Studios   Artists and illustrators can evoke the complexity of fur or vegetation with relatively few well-placed strokes. The research presented in this paper adapts this approach to render 3D computer graphics scenes in a stylized manner that suggests the complexity of the scene without explicitly representing it. The method renders moderately complex scenes at multiple frames per second on current graphics workstations, providing a measure of inter-frame coherence to avoid a distracting appearance/disappearance of detail.   Balancing Fusion, Image Depth and Distortion in Stereoscopic Head-Tracked Displays Zachary Wartell, Larry Hodges & William Ribarsky Georgia Institute of Technology   Analysis shows that even with perfect head tracking, a user will perceive virtual objects to warp and shift as the head moves. This paper presents a new technique for counteracting the removable components of distortion as well as new methods for managing image fusion problems for distant objects and for enhancing the depth of flat scenes.   Cognitive Modeling: Knowledge, Reasoning, and Planning for Intelligent Characters John Funge & Xiaoyuan Tu Intel Corporation   Demetri Terzopoulos University of Toronto   Recent work in behavioral animation has taken impressive steps toward autonomous, self-animating characters for use in production animation and interactive games. Cognitive models go beyond behavioral models by governing what a character knows, how that knowledge is acquired, and how it can be used to plan actions. With cognitively empowered characters, the animator need only specify a behavior outline or "sketch plan" and, through reasoning, the character will automatically work out a detailed sequence of actions meeting the specification.   Creating a Live Broadcast from a Virtual Environment Chris Greenhalgh, Steve Benford & Ian Taylor University of Nottingham   John Bowers Royal Institute of Technology   Graham Walker BT Laboratories   John Wyver Illuminations Television   "Inhabited television" combines multi-user virtual environments with television, so that online audience members can participate in TV shows staged in a virtual world. The resulting program is presented simultaneously both to conventional passive viewers and to online participants, benefiting in many cases from being broadcast live.   Emancipated Pixels: Real-World Graphics in the Luminous Room John Underkoffler, Brygg Ullmer, & Hiroshi Ishii MIT Media Lab   This paper presents a conceptual infrastructure for providing graphical display and interaction at each of an interior architectural space's various surfaces, arguing that such pervasive spatial output and input is one natural heir to today's rather more limited notion of spatially-confined, output-only display (the CRT). The requirements of such real-world graphics, including computational and networking demands; schemes for spatially omnipresent capture and display; and issues that attend the design of interactions in an environment of this sort are discussed.   LCIS: A Boundary Hierarchy For Detail-Preserving Contrast Reduction Jack Tumblin & Greg Turk Georgia Institute of Technology   High-contrast scenes are difficult to depict on low-contrast displays without loss of important fine details and textures. Perhaps the best renditions are created by skilled artists painting a hierarchy of boundaries and shadings in progressive image refinement. The authors' method builds a similar mathematical hierarchy using "low curvature image simplifiers" (LCIS) to construct a high-detail, low-contrast display image by compressing only the large features, then adding back all small details. LCIS is extendable to higher dimensions and may also be useful for electronic photography without clipping or saturation, as well as an artistic tool for image editing.   Stable Fluids Jos Stam Alias|Wavefront   Building animation tools for fluid-like motions is an important and challenging problem with many applications in computer graphics. The use of physics-based models for fluid flow can greatly assist in creating such tools, and the stability of this model allows us to take larger time steps and therefore achieve faster simulations.   The VolumePro Real-Time Ray-Casting System Hanspeter Pfister, Jan Hardenbergh, Jim Knittel, Hugh Lauer, Larry Seiler MERL- A Mitsubishi Electric Research Laboratory   This paper describes the world's first single-chip, real-time volume rendering system for PC class computers. The system renders more than 500 million interpolated, Phong-illuminated composited samples per second. This is sufficient to render a 2563 volume at 30 frames per second.