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Item Adaptive Compression of Human Animation Data(Eurographics Association, 2002) Ahmed, Amr Adel Hassan; Hilton, Adrian; Mokhtarian, FarzinIn this paper we introduce an adaptive motion compression technique using the discrete wavelet transform. Based on the analysis of human animation data, and its frequency contents, the wavelet analysis is utilised to achieve motion compression. It has been found that even with high compression ratios (up to 86%), the compressed animation is visually very close to the original animation. This property is potentially useful for many areas of animation such as motion interpolation/blending and networked virtual environments. One of our motivations is that motion blending/interpolation between motion capture samples is one of the successful techniques for synthesis of novel realistic human animation. One of the major concerns of that method is the increase of the database size with the large number of samples required to synthesise a wide range of movements. Previous research has addressed this issue by trying to reduce the number of samples required for interpolation. The approach that we introduce in this paper is to reduce the individual sample’s size using compression. Integration of both these approaches promises to allow a realistic animation with reduced database size. In networked virtual environments and on-line games, compressing the animation data can reduce the transmission load and help in achieving real-time performance and realism with reduced cost.Item Mesh Decimation for Displacement Mapping(Eurographics Association, 2002) Collins, Gordon; Hilton, AdrianWe present a mesh decimation algorithm for triangular meshes. Unlike other decimation algorithms we are not concerned with geometric error but with the existence of a displacement mapping which can map between the original and decimated meshes. We use the implicit function theorem to derive a condition which ensures the existence of a displacement map. The algorithm is applied to some standard scanned models and reduction rates around 99% are seen.Item 4D Video Textures for Interactive Character Appearance(The Eurographics Association and John Wiley and Sons Ltd., 2014) Casas, Dan; Volino, Marco; Collomosse, John; Hilton, Adrian; B. Levy and J. Kautzanimation from a database of 4D actor performance captured in a multiple camera studio. 4D performance capture reconstructs dynamic shape and appearance over time but is limited to free-viewpoint video replay of the same motion. Interactive animation from 4D performance capture has so far been limited to surface shape only. 4DVT is the final piece in the puzzle enabling video-realistic interactive animation through two contributions: a layered view-dependent texture map representation which supports efficient storage, transmission and rendering from multiple view video capture; and a rendering approach that combines multiple 4DVT sequences in a parametric motion space, maintaining video quality rendering of dynamic surface appearance whilst allowing high-level interactive control of character motion and viewpoint. 4DVT is demonstrated for multiple characters and evaluated both quantitatively and through a user-study which confirms that the visual quality of captured video is maintained. The 4DVT representation achieves >90% reduction in size and halves the rendering cost.Item Enriching Animation Databases(Eurographics Association, 2004) Ahmed, Amr; Mokhtarian, Farzin; Hilton, Adrian; M. Alexa and E. GalinThe paper presents a framework for enriching an existing basic animation databse by modifying existing motions to generate a variety of new motions. Intuitively controlled motion varities are generated on demand which reduces the storage requirements, avoids recapturing missing variations, and provides greater flexibility and utilisation of existing clips. An improved root-trajectory blending is introduced that overcomes the limitations of ordinary blending (including flipping of the root trajectory when blending motions of opposite path-curvature or opposite directions). A novel synchronised mirror technique is also introduced.Item Parametric Motion Blending through Wavelet Analysis(Eurographics Association, 2001) Ahmed, Amr; Mokhtarian, Farzin; Hilton, AdrianThis paper shows how multiresolution blending can be employed with time-warping for realistic parametric motion generation from pre-stored motion data. The goal is to allow the animator to define the desired motion using its natural parameters such as speed. Generation of a realistic motion is achieved using pre-stored captured animations. Analysis has been carried out to investigate the relationship between the walking speed and blending factor to remove the burden of trial and errors from the animator. As a result, realistic walking motion with the speed specified by the user can be generated. This desired speed should be between the minimum and maximum speeds of the available motion data. Analysis to generalise these results to other motions are in progress. Generating the desired motion for different scaled avatars is also discussed.Item Cyclification of Human Motion for Animation Synthesis(Eurographics Association, 2003) Ahmed, Amr; Mokhtarian, Farzin; Hilton, AdrianIn this paper, new techniques are introduced for matching cyclic motion boundaries by using simple animation processing algorithms based on some observed characteristics from different families of cyclic motions. Matching the cycle boundaries is one of the essential stages in generating a stream of animation of cyclic human movements. If the cycle boundaries are not matched, noticeable artefacts and flickers will appear regardless of how realistic the available motion cycle is. The proposed techniques are developed to modify the motion cycle even in the case, where only one cycle is provided. These techniques do not only match the cycle boundaries but also correct other parts of the cycle and motion constraints. The techniques are computationally efficient as they work directly on the animation data (without conversion to intermediate representations such as spline or time-frequency transforms). Moreover, many aspects of animation (including joint limits and important motion constraints) are preserved as the modification is guided by the original motions. A simple framework for automatic detection of gait phases timing is also introduced.