. This paper presents the foundations of IBAL, a general specification for scene animation. IBAL regulates interactions among graphical elements, such as geometric models and behavioral algorithms, to describe animated scenes. Interactions among graphical elements are managed by primitives which are arranged into three graphs. The three graphs logically partition an animation into "who," "what," and "when." IBAL's unique design permits applications to represent, save, and restore a wide variety of complex scenes. A short summary of existing formats for scene modeling and scene animation is presented to distinguish and to assess the utility of IBAL's design. Keywords: Scene Animation, General Specification, Software Interaction 1 Introduction Computer animation is the development and production of computer animated scenes. Animated scenes consist of many graphical elements interacting over time. Graphical elements are geometric models, algorithms, and data structures that define the s...

This paper proposes a classification of existing file formats for computer animation. File formats for computer animation store and describe the evolution of virtual scenes over time. They permit applications, which produce animating scenes, to share and to exchange information. File Formats are classified by the information they store and by what means they store the information. 1 Introduction File formats establish specifications to store information onto data files. The information is arranged methodologically for development and easy retrieval. File formats for animation describe the contents or results of a time-varying scene. Computers playback the animations which the file formats describe. A time-varying scene consists of many scene elements that change state over time. Scene elements represent visible entities, such as shapes and figures, and invisible entities, such as behavioral models and temporal strategies. Each is equally important to control and to specify scene chan...

CAD systems are usually based on a tensor product representation of free form surfaces. In this case, trimmed patches are used for modeling non rectangular zones. Trimmed patches provide a reasonable solution for the representation of general topologies, provided that the gap between equivalent trimming curves in the euclidean space is small enough. Several commercial CAD systems, however, represent certain non rectangular surface regions through degenerate rectangular patches. Degenerate patches produce rendering artifacts and can lead to malfunctions in the subsequent geometric operations. In the present paper, two algorithms for converting degenerate tensor-product patches into triangular and trimmed rectangular patches are presented. The algorithms are based on specific degree reduction algorithms for B'ezier curves. In both algorithms, the final surface approximates the initial one in a quadratic sense while inheriting its boundary curves. In the second one, " \Gamma G 1 cont...