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SECTION 4
Animation and Simulation
In a movie theater, animation is achieved by taking a sequence of pictures, and then projecting them at 24 frames per second on the screen. Videotape is shown at 30 frames per second. Computer animation is achieved by refreshing the screen display with a sequence of images at 60-120 frames per second. Of course, we can use fewer images to refresh 60 frames of screen in a second, so that some images will be used to refresh the display more than one time. The fewer the number of different images displayed in a second, the jerkier the animation will be.Keyframe animation is achieved by pre-calculating keyframe images and in-between images, which may take significant amount of time, and then display (play-back) the sequence of generated images in real time.
Keyframe animation is often used in visual effects in films and TV commercials, which no interactions or unpredictable changes are necessary. Interactive animation, on the other hand, is achieved by calculating, generating, and displaying the images at the same time on the fly. When we talk about real-time animation, we mean the virtual animation happens in the same time frames as in real world behavior. However, for graphics researchers, real-time animation often simply implies the animation is smooth or interactive. Real-time animation is often used in virtual environment for education, training, and 3D games. Many modeling and rendering tools, such as 3D Studio Max, Maya, and MultigenPro, are also animation tools. Animation is closely related to and associated with simulation.
Simulation, on the other hand, often means a process of generating certain natural phenomena through scientific computation. The results of the simulations may be large datasets of atomic activities (positions, velocities, pressures and other parameters of atoms) or fluid behaviors (volume of vectors and pressures). Computer simulation allows scientists to generate the atomic behavior of certain nanostructured materials for understanding material structure and durability and to find new compounds with superior quality. Simulation integrated with visualization can help pilots learn to fly and aid automobile designers to test the integrity of the passenger compartment. For many computational scientists, simulation may not be related to any visualization at all. However, for many graphics researchers, simulation often means simply animation. Today, graphical simulation, or simply simulation, is an animation of certain process or behavior that are generated often through scientific computation and modeling.8 Here we emphasize an integration of simulation and animation -- the simulated results are used to generate graphics model and control animation behaviors. It is far easier, cheaper, and safer to experiment with a model through simulation than with a real entity. In fact, in many situations, such as training space-shuttle pilots and studying molecular dynamics, modeling and simulation are the only feasible method to achieve the goals. Real-time simulation is an overloaded term. To computational scientists, it often means the simulation time is the actual time in which the physical process (under simulation) should occur. In automatic control, it means the output response time is fast enough for automatic feedback and control. In graphics, it often means that the simulation is animated at an interactive rate of our perception. The emphasis in graphics is more on responsiveness and smooth animation rather than strictly accurate timing of the physical process. In many simulation-for-training applications, the emphasis is on generating realistic behavior for interactive training environment rather than strictly scientific or physical computation.
Vega is MultiGen-Paradigm’s software environment for real-time visual and audio simulation, virtual reality, and general visualization applications. It provides the basis for building, editing, and running sophisticated applications quickly and easily. It simplifies development of complex applications such as flight simulation, simulation-based design, virtual reality, interactive entertainment, broadcast video, CAD, and architectural walk-through. EON Studio is a comprehensive tool box for creating and deploying interactive real-time 3D simulations on the Windows platforms. Popular application areas include marketing and sales tools, product development, simulation based training, architectural studies, and community planning.
Activeworlds is a collection of networked virtual environments for interactive shopping, gaming, and chatting. It’s a networked virtual environment that provides a range of user, client, server, and development applications. WorldUp is a 3D modeling, rendering, and simulation tool good at creating various VR worlds. 20-sim is a modeling and simulation program for electrical, mechanical, and hydraulic systems or any combination of these systems. VisSim/Comm is a Windows-based modeling and simulation program for end-to-end communication systems at the signal or physical level. It provides solutions for analog, digital, and mixed-mode communication system designs. SIMUL8 is a visual discrete event simulation tool. It provides performance measures and insights into how machines and people will perform in different combinations. Mathematica is an integrated environment that provides technical computing, simulation, and communication. Its numeric and symbolic computation abilities, graphical simulation, and intuitive programming language are combined with a full-featured document processing system. As we discussed earlier MATLAB, Khoros, and many other tools contains modeling and simulation functions.
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