Animation on the web: a survey <s> Overview Of The Challenges <s> An efficient algorithm for compression of dynamic time-consistent 3D meshes is presented. Such a sequence of meshes contains a large degree of temporal statistical dependencies that can be exploited for compression using DPCM. The vertex positions are predicted at the encoder from a previously decoded mesh. The difference vectors are further clustered in an octree approach. Only a representative for a cluster of difference vectors is further processed providing a significant reduction of data rate. The representatives are scaled and quantized and finally entropy coded using CABAC, the arithmetic coding technique used in H.264/MPEG4-AVC. The mesh is then reconstructed at the encoder for prediction of the next mesh. In our experiments we compare the efficiency of the proposed algorithm in terms of bit-rate and quality compared to static mesh coding and interpolator compression indicating a significant improvement in compression efficiency. <s> BIB001 </s> Animation on the web: a survey <s> Overview Of The Challenges <s> 3D triangle meshes are extremely used to model discrete surfaces, and almost always represented with two tables: one for geometry and another for connectivity. While the raw size of a triangle mesh is of around 200 bits per vertex, by coding cleverly (and separately) those two distinct kinds of information it is possible to achieve compression ratios of 15:1 or more. Different techniques must be used depending on whether single-rate vs. progressive bitstreams are sought; and, in the latter case, on whether or not hierarchically nested meshes are desirable during reconstruction. <s> BIB002 </s> Animation on the web: a survey <s> Overview Of The Challenges <s> Dynamic 3D mesh sequences, also called 3D animation, have been widely used in the movie and gaming industries. However, the huge storage requirements of dynamic mesh data make it problematic for a number of applications such as rendering, transmission over a network, and displaying on mobile devices. This paper proposes a multi resolution representation of 3D animation that results displaying 3D animation progressively. The proposed method transforms traditional 3D animation representation into progressive representation, which takes up less storage and memory space. The progressive representation is constructed by compressing the animation into a base animation with sequenced refining operators. The base animation is viewable and can be reconstructed by transmitting for only a few seconds, which is also called thumbnail animation in this paper, the more detailed animation can be refined smoothly with applying refining operators. As the results, the resolution of animation can be free to change at real-time, where the resolution can be increased automatically or even controlled by user. Moreover, the progressive animation is more suitable for transmitting and displaying through the network. <s> BIB003 </s> Animation on the web: a survey <s> Overview Of The Challenges <s> We present a fully automatic approach to real-time facial tracking and animation with a single video camera. Our approach does not need any calibration for each individual user. It learns a generic regressor from public image datasets, which can be applied to any user and arbitrary video cameras to infer accurate 2D facial landmarks as well as the 3D facial shape from 2D video frames. The inferred 2D landmarks are then used to adapt the camera matrix and the user identity to better match the facial expressions of the current user. The regression and adaptation are performed in an alternating manner. With more and more facial expressions observed in the video, the whole process converges quickly with accurate facial tracking and animation. In experiments, our approach demonstrates a level of robustness and accuracy on par with state-of-the-art techniques that require a time-consuming calibration step for each individual user, while running at 28 fps on average. We consider our approach to be an attractive solution for wide deployment in consumer-level applications. <s> BIB004
Animation on the web as compared to normal animation comes with its own set of challenges and requirements. Regular animation maybe carried out by accessing a sequence of 3D models or by virtue of some sort of physic-based methods, which are employed to create a time based state of the animation model called key-frames. For successful animation, there should be sufficient control points or governing rules to create key-frames. Using some form of extrapolation or interpolation techniques, subsequent frames are generated and rendered, in a time-elapsed manner, onto the screen. Computation and rendering of complex 3D objects is processor intensive, and level of detail (LOD) techniques are sometimes utilized in order to expedite the process. LOD techniques increase or decrease the complexity of the 3D object depending on the distance of the object from the camera. In online rendering, with a modern web browser as our canvas (rendering context) the paramount information is to have all the required data files for computing and rendering in order to reproduce the animation on the client end. But animation data can be voluminous and require a lot of space, which is not desired on a sandboxed environment as in a browser, hence efficient compression algorithms need to be applied on the base animation file, so that it can be transmitted as fast as possible and can be rebuilt with minimal information. Employing various LOD techniques can further reduce the data for transmission. And these transmitted data can be sent in a structured manner to reduce the computation time on the client side. JavaScript is mostly used to process data and rendering. There are lots of research for compression and transmission of static 3D objects BIB002  and dynamic 3D BIB001 BIB003 BIB004 objects and some of these techniques can be extended for animation files. But there is lack of uniformity among the various techniques used as well as among various technological standards on the web  KhronosGroup 2014] . Hence, one method could decimate the whole 3D object and employ a spatial data structure in order to traverse through the structure for different LOD, or another would split the 3D object in a coherent manner and transmit in a structured manner. It all boils down to the particular requirement or the format of the existing 3D object. There is a need for a schema-less, encoding agnostic, structured or compatible format which could support 3D files without any dependency.