In this paper, we present an expressive 3D animation environment that enables users to rapidly and visually prototype animated worlds with a fully 3D user-interface. A 3D device allows the specification of complex 3D motion, while virtual tools are visible mediators that live in the same 3D space as application objects and supply the interaction metaphors to control them. In our environment, there is no intrinsic difference between userinterface and application objects. Multi-way constraints provide the necessary tight coupling among components that makes it possible to seamlessly compose animated and interactive behaviors. By recording the effects of manipulations, all the expressive power of the 3D user interface is exploited to define animations. Effective editing of recorded manipulations is made possible by compacting all continuous parameter evolutions with an incremental data-reduction algorithm, designed to preserve both geometry and timing. The automatic generation of editable representations of interactive performances overcomes one of the major limitations of current performance animation systems. Novel interactive solutions to animation problems are made possible by the tight integration of all system components. In particular, animations can be synchronized by using constrained manipulation during playback. The accompanying video-tape illustrates our approach with interactive sequences showing the visual construction of 3D animated worlds. All the demonstrations in the video were recorded live and were not edited.

We are interested in providing animators with a general-purpose tool allowing them to create animations using straight-ahead actions as well as pose-to-pose techniques. Our approach seeks to bring the expressiveness of real-time motion capture systems into a general-purpose multi-track system running on a graphics workstation. We emphasize the use of high-bandwidth interaction with 3D objects together with specific data reduction techniques for the automatic construction of editable representations of interactively sketched continuous parameter evolution. In this paper, we concentrate on providing a solution to the problem of applying data reduction techniques in an animation context. The requirements that must be fulfilled by the data reduction algorithm are analyzed. From the Lyche and Mørken knot removal strategy, we derive an incremental algorithm that computes a B-spline approximation to the original curve by considering only a small piece of the total curve at any time. This algorithm allows the processing of the user's captured motion in parallel with its specification, and guarantees constant latency time and memory needs for input motions composed of any number of samples. After showing the results obtained by applying our incremental algorithm to 3D animation paths, we describe an integrated environment to visually construct 3D animations, where all interaction is done directly in three dimensions. By recording the effects of user's manipulations and taking into account the temporal aspect of the interaction, straight-ahead animations can be defined. Our algorithm is automatically applied to continuous parameter evolution in order to obtain editable representations. The paper concludes with a presentation of future work. C-242 J-F. Balaguer et al. / Sketching 3D Animations © Eurographics Association, 1995 © Eurographics Association, 1995 J-F. Balaguer et al. / Sketching 3D Animations C-243requirements that must be fulfilled by the data reduction algorithm. In particular, the following points must be considered. Preservation of geometry and timing:The computed curve must not only precisely approximate the geometry, as it is required in modeling and drafting tools, but also the timing of the initial data. In the case of interactively specified data, both components are defined with a limited precision and should be efficiently smoothed by the approximating curve while preserving the correspondence between the geometry and timing. This implies that the data reduction algorithm must treat both components simultaneously, since treating them independently may introduce errors difficult to control, Generality: The algorithm may be used to compute approximations of data generated by various sources. In particular, we shall consider the cases of interactively specified data presenting a non negligible amount of noise and imprecision, as well as highly accurate data generated by evaluating a mathematical model, as when using data reduction to convert the output of a simulation engine to a keyframing representatio...

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We are interested in providing animators with a general‐purpose tool allowing them to create animations using straight‐ahead actions as well as pose‐to‐pose techniques. Our approach seeks to bring the expressiveness of real‐time motion capture systems into a general‐purpose multi‐track system running on a graphics workstation. We emphasize the use of high‐bandwidth interaction with 3D objects together with specific data reduction techniques for the automatic construction of editable representations of interactively sketched continuous parameter evolution. In this paper, we concentrate on providing a solution to the problem of applying data reduction techniques in an animation context. The requirements that must be fulfilled by the data reduction algorithm are analyzed. From the Lyche and Mørken knot removal strategy, we derive an incremental algorithm that computes a B‐spline approximation to the original curve by considering only a small piece of the total curve at any time. This algorithm allows the processing of the user's captured motion in parallel with its specification, and guarantees constant latency time and memory needs for input motions composed of any number of samples. After showing the results obtained by applying our incremental algorithm to 3D animation paths, we describe an integrated environment to visually construct 3D animations, where all interaction is done directly in three dimensions. By recording the effects of user's manipulations and taking into account the temporal aspect of the interaction, straight‐ahead animations can be defined. Our algorithm is automatically applied to continuous parameter evolution in order to obtain editable representations. The paper concludes with a presentation offuture work.

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