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Event Wrap-Up: Over 27,000 game developers, film industry professionals, and scientists attended SIGGRAPH 2004 at the Los Angeles Convention Center from August 8th to the 12th, 2004, to discuss the latest developments in 3D graphics. This SIGGRAPH's forecast for the future of game development: radically more programmable graphics cards, smart and flexible art tools, and real 3D displays.
Several events ran simultaneously during the week at the conference, forming tracks for all aspects of game development. For example, visual art insiders reviewed new films and cut-scenes. Even those who didn't understand the details could ogle the amazing effects. This year's SIGGRAPH favorites include the Onimusha 3 cut-scene with the ninja boss, shown theater size, and Pixar's new Boundin' short with a Jackalope hero. Artists also checked out the Guerrilla Studio to experiment with the latest tools for free, including motion capture and beefy workstations loaded up with MAX and other modelers. For particularly abstract creative types, there was even a CyberFashion Show which displayed cyberpunk-esque fashions reminiscent of Giger and The Matrix. SIGGRAPH and the Importance Of Graphical Research With games like Far Cry, Doom 3, Half-Life 2, and S.T.A.L.K.E.R. hitting shelves this year, one might wonder what is left to research in the graphical arena. Why should we track seemingly theoretical graphics research in the games industry? Well, obviously, despite the visual success of today's games, there's a lot of work left in computer graphics. Although real-time rendering has made incredible strides, look at the content creation process and the run-time animation in your current product. If your studio is like most, creation aspects are mostly unchanged in the last 5-10 years. Artists tweak vertices around to create models, a time-consuming way of translating their vision into data. Those models then appear in the game mostly as pre-animated set pieces. But even with great AI, characters look stupid when their dead eyes gaze into the distance or they fail to shift their weight walking over rubble. So, with the lion's share of budget, schedule, and head count for new games devoted to content creation, many are trying out ways to make the art process easier, cheaper, and faster. We should also get the most out of every asset by letting gamers interact with them in new ways. Let's look at some of the new ideas from the research community that will make this possible. Mesh Editing Artists create models by deforming basic shapes, and by piecing together previous models and carefully fixing seams. It takes years to learn to make the first model and days to create the hundredth. The process is time-consuming because it forces the artist to work with vertices and texture coordinates. But imagine an editor in which you instead start creating a rocking chair model by searching a database for "chair" and a 3-stroke sketch that looks like a lower-case "h". The search engine returns hundreds of chairs -- you select the back of one, the legs of another, the seat from a third, and so on. The editor then intelligently cuts the various parts from the original models, normalizes the scale and merges them into a seamless new mesh. This is the powerful new vision offered by the Modeling by Example project. The current system can do all of the above and is usable by both professional artists and amateurs (now "programmer art" doesn't have to be so embarrassing!)
The system described at SIGGRAPH has no notion of material properties or texture, cannot yet work with animated models, and lacks the traditional tools that will still be needed in this brave new world for tweaking smaller areas. But even though search-based editing isn't ready to appear in the next version of your favorite modeling software, it is clearly a compelling alternative that should be further developed. For in-house tools, the ideas of a smart 3D lasso and smooth melding of adjacent shapes are appropriate now, and should be on artists' wish lists. Beyond the Modeling by Example paper, the SIGGRAPH Proceedings contains two other papers likely to be useful when implementing these ideas. The energy-minimizing curves needed for the smart lasso idea are further explored in Energy-Minimizing Splines in Manifolds. Mesh Editing With Poisson-Based Gradient Field Manipulation is an alternative method for creating the water-tight seams. Elsewhere on the modeling front, NURBS are a popular modeling primitive for creating curved surfaces from a set of 3D control points. They appear in many modeling tools. Last year, Sederberg et al. introduced the T-Spline generalization of NURBS that can specify the same surfaces with only a third as many control points. This year, T-Spline Simplification and Local Refinement shows how to convert an existing NURBS model, thus eliminating many control points, and how to locally refine T-splines so that artists can selectively add detail without excessive control points and without cracks in the model. Modeling programs and level editors that incorporate these new T-splines should allow artists to create the same models with less effort. Textures A number of papers introduce tools for better accomplishing the texture editing tasks for which PhotoShop's Magic Wand and Clone Brush are typically employed. Interactive Digital Photo Montage seamlessly stitches together multiple images using a few casual mouse strokes. Lazy Snapping, GrabCut, and Poisson Matting use radically different methods from one another to achieve the same results. In each case, an object can be cleanly clipped from its background, including fractional alpha values along the edge, by dragging a box and making a handful of mouse strokes. Compared to the current process of carefully selecting objects with the magnetic lasso and Magic Wand and then manually cleaning edges, these new methods appear painless and make image compositing fun again. One challenge for both modeling objects that are cut from blocks of material, like statues and caves, and simulating breakable objects in games, is that texture is only skin deep because it is painted on the surface. 3D textures are now supported by graphics hardware and can solve this problem. But how can artists create 3D textures? For 2D textures, we take photographs of real materials and use functions to simulate noisy patterns like spots and stripes. The new Volumetric Illustration method simulates plausible texture for 3D cross-sections given example photographs of real cross-sections. In one example from the paper, the authors use a single photograph of a steak to simulate internal texture throughout an animal, complete with fat striations and different layers of muscle tissue. Stereological Techniques for Solid Textures is an alternative method for materials like rock that contain oddly sized and colored particles within a substrate. This method takes a cross-section photograph, measures the statistical shape and distribution of particles and then synthesizes a 3D volume.
Animation Four
papers describe new methods for realistic human motions for both
real-time and pre-computed animations relevant to games. Speaking
with Hands uses pre-processed speech snippets and animations
to synthesize new, synchronized animations and speech at run time.
They demonstrated Zoe from Electronic Arts' SSX 3 giving
animated feedback to the player based on their specific actions.
The result was believable and as natural as any 'hip and cool' teenage
snowboarder can be.
Elsewhere, Synthesizing Physically Realistic Human Motion in Low-Dimensional Behavior Specific Spaces presents a new method for optimizing human motion as an offline process. It's something you can imagine incorporated into Character Studio for editing motion capture of a walk cycle to realistically incorporate other motions like jumping and crouching. Synthesizing Animations of Human Manipulation Tasks is another interesting technique for offline generation of canned animations. It combines AI with animation to create whole animations of characters solving simple physical tasks, like placing a large box in the trunk of a car. The results look great for the simple cases shown in the paper. The character balances her weight appropriately, avoids collisions, and minimizes the energy needed for a task. Poses created with inverse kinematics, either in real-time or by an artist, obey joint limits but look rather uncomfortable because they don't understand the human body. Style-Based Inverse Kinematics is a new approach to IK that uses a learned model of human poses to produce poses that are likely, instead of just physically possible. Once the data has been learned the method executes in real-time and could be integrated directly into game physics or offline animation packages. From a game programmer's perspective, the drawback of learning-based algorithms is that they are useless without the original data set. However, it would be extremely helpful in implementing this method if the learned parameters for a variety of human figures were made publicly available.
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Introduction
Features
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