Animation on the web: a survey <s> Compression and Preprocessing <s> Many applications in computer graphics require complex, highly detailed models. However, the level of detail actually necessary may vary considerably. To control processing time, it is often desirable to use approximations in place of excessively detailed models. We have developed a surface simplification algorithm which can rapidly produce high quality approximations of polygonal models. The algorithm uses iterative contractions of vertex pairs to simplify models and maintains surface error approximations using quadric matrices. By contracting arbitrary vertex pairs (not just edges), our algorithm is able to join unconnected regions of models. This can facilitate much better approximations, both visually and with respect to geometric error. In order to allow topological joining, our system also supports non-manifold surface models. CR Categories: I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling—surface and object representations <s> BIB001 </s> Animation on the web: a survey <s> Compression and Preprocessing <s> In computer graphics, many automatic methods for simplifying polygonal meshes have been developed. These techniques work very well for static meshes; however, they do not handle the case of deforming objects. Simplifying any single pose of a deforming object may destroy detail required to represent the shape in a different pose. We present an automatic technique for simplifying deforming character meshes that takes a set of examples as input and produces a set of simplied examples as output. The method preserves detail required for deformation and maintains connectivity information across the examples. This technique is applicable to many current skinning algorithms including example-driven techniques, tting techniques and Linear Blend Skinning. <s> BIB002 </s> Animation on the web: a survey <s> Compression and Preprocessing <s> The cartridge is made of plastic material and comprises a shell having an exit slot and end covers mounted at the ends of said shell. The cartridge consists of three substantially semicylindrical members, which by means of two hinges are connected to each other so that two semicylindrical members when folded together constitute a shell which encloses the roll of film and the third semicylindrical member covers said shell and defines a film passage in the shape of an arc of a circle, and the exit slot of the cartridge, and the two outer semicylindrical members are interconnected. <s> BIB003 </s> Animation on the web: a survey <s> Compression and Preprocessing <s> Real-time animation of human-like characters has been an active research area in computer graphics. Nowadays, more and more applications need to render various realistic scenes with human motion in crowds for interactive virtual environments. Animation and level of detail are well explored fields but little has been done to generate level of detail automatically for dynamic articulated meshes. Our approach is based on the combination of three interesting layers for run-time level of detail in character crowd animation: the skeleton, the mesh and the motion. We build a Multiresolution Skeletal Graph to simplify the skeleton topology progressively. In contrast with previous works, we use a Dual-Graph Based Simplification for articulated meshes, where the triangle decimation is driven by triangle compactness, to build a dynamic, continuous, progressive and selective mesh level of detail. We also present Power Skinning to ensure the stability of Linear Smooth Skinning, during the simplification, with an efficient multi-weight update rule. <s> BIB004 </s> Animation on the web: a survey <s> Compression and Preprocessing <s> Transmission of Web3D media over the Internet can be slow, especially when downloading huge 3D models through relatively limited bandwidth. Currently, 3D compression and progressive meshes are used to alleviate the problem, but these schemes do not consider similarity among the 3D components, leaving rooms for improvement in terms of efficiency. This paper proposes a similarity-aware 3D model reduction method, called Lightweight Progressive Meshes (LPM). The key idea of LPM is to search similar components in a 3D model, and reuse them through the construction of a Lightweight Scene Graph (LSG). The proposed LPM offers three significant benefits. First, the size of 3D models can be reduced for transmission without almost any precision loss of the original models. Second, when rendering, decompression is not needed to restore the original model, and instanced rendering can be fully exploited. Third, it is extremely efficient under very limited bandwidth, especially when transmitting large 3D scenes. Performance on real data justifies the effectiveness of our LPM, which improves the state-of-the-art in Web3D media transmission. <s> BIB005 </s> Animation on the web: a survey <s> Compression and Preprocessing <s> A problem that still remains with today's technologies for 3D asset transmission is the lack of progressive streaming of all relevant mesh and texture data, with a minimal number of HTTP requests. Existing solutions, like glTF or X3DOM's geometry formats, either send all data within a single batch, or they introduce an unnecessary large number of requests. Furthermore, there is still no established format for a joined, interleaved transmission of geometry data and texture data. Within this paper, we propose a new container file format, entitled Shape Resource Container (SRC). Our format is optimized for progressive, Web-based transmission of 3D mesh data with a minimum number of HTTP requests. It is highly configurable, and more powerful and flexible than previous formats, as it enables a truly progressive transmission of geometry data, partial sharing of geometry between meshes, direct GPU uploads, and an interleaved transmission of geometry and texture data. We also demonstrate how our new mesh format, as well as a wide range of other mesh formats, can be conveniently embedded in X3D scenes, using a new, mini-malistic X3D ExternalGeometry node. <s> BIB006
Level of Detail: Another issue is the reduction of quality and detail of the mesh in interactive applications. LOD concepts such as Progressive meshes  ] help render according to the scene details either by mesh simplification process or by exploiting progressive transmission and decompression schemes. Mesh Level of Detail: Representation of objects based on their distance from the camera with lower LOD for distant object and higher LOD for nearer object, the interactivity and rendering of the 3D scenes can be improved a lot. According to BIB004 , there are no algorithms that excel at simplifying animated models and in achieving high fidelity of the original mesh. Either there are quantization metric measures for surface simplification and preserving the topology using Quadric Error Metric (QEM) by BIB001 ; or the most popular real-time triangle reduction for polygon manifolds, introduced by Hoppe et al., Progressive Meshes [1996] . Ensuring the best quality of a mesh simplification requires huge computational costs, and sometimes for no significant visual improvement. Animation Level of Detail: Simplification techniques work well for static meshes but not so much for deformable objects. Deformation Sensitive Decimation (DSD) by BIB002 was based on the idea of QEM BIB001 , for measuring the contraction cost of edges. BIB003  Wen et al. BIB005 ] presents a similarity aware 3D model reduction method, which searches for similar component in the 3D model and reuse them through the construction of Lightweight Scene Graph (LSG), It doesn't require any decompression at the client end and required LOD is obtained with help of instance rendering. The objective of progressive compression is to speed up transmission over the network, but if decompression takes as long on the client side, then there is no point in applying fancy techniques and data structures. It needs to rely on simple yet effective algorithm, which could easily transcribe itself onto JavaScript and WebGL. BIB006 