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Scalable l-infinite coding of Meshes

IEEE TRANSACTIONS ON VISUAlIZATION AND COMPUTER GRAPHICS 2010年第3期16卷 513-528页

作者： Munteanu, Adrian Cernea, Dan C. Alecu, Alin Cornelis, Jan Schelkens, Peter Vrije Univ Brussel Interdisciplinary Inst Broadband Technol IBBT Dept Elect & Informat ETRO B-1050 Brussels Belgium

The paper investigates the novel concept of local-error control in mesh geometry encoding. In contrast to traditional mesh-coding systems that use the mean-square error as target distortion metric, this paper proposes a new l-infinite mesh-coding approach, for which the target distortion metric is the l-infinite distortion. In this context, a novel wavelet-based l-infinite-constrained coding approach for meshes is proposed, which ensures that the maximum error between the vertex positions in the original and decoded meshes is lower than a given upper bound. Furthermore, the proposed system achieves scalability in l-infinite sense, that is, any decoding of the input stream will correspond to a perfectly predictable l-infinite distortion upper bound. An instantiation of the proposed l-infinite-coding approach is demonstrated for MESHGRID, which is a scalable 3D object encoding system, part of MPEG-4 AFX. In this context, the advantages of scalable l-infinite coding over l-2-oriented coding are experimentally demonstrated. One concludes that the proposed l-infinite mesh-coding approach guarantees an upper bound on the local error in the decoded mesh, it enables a fast real-time implementation of the rate allocation, and it preserves all the scalability features and animation capabilities of the employed scalable mesh codec.

关键词： l-infinite coding l-2 coding scalable mesh coding MESHGRID 3D graphics MPEG4-AFX 1-CPRS

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THEORETICAl DISTORTION ESTIMATION IN l-infinite WAVElET-BASED coding OF SEMI-REGUlAR MESHES

THEORETICAL DISTORTION ESTIMATION IN L-INFINITE WAVELET-BASE...

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20th European Signal Processing Conference (EUSIPCO)

作者： Florea, Ruxandra Denis, leon lievens, Jan Schelkens, Peter Munteanu, Adrian Vrije Univ Brussel Dept Elect & Informat ETRO B-1050 Brussels Belgium

ISBN: (纸本)9781467310680

Subdivision-based wavelet coding techniques yield state-of-the-art performance in scalable compression of semi-regular meshes. However, all these codecs make use of the l-2 distortion metric, which gives only a good approximation of the global error produced by lossy coding of the wavelet coefficients. The l-infinite metric has been proven to be a suitable metric for applications where controlling the local, maximum error on each vertex is of critical importance. In this context, an upper bound formulation for the l-infinite distortion for a wavelet-based coding scheme operating on semi-regular meshes is derived. In addition, we propose a rate-distortion optimization algorithm that minimizes the rate for any target l-infinite distortion. It is shown that our l-infinite coding system outperforms the state-of-the-art and that an l-2 driven coding approach for semi-regular meshes loses ground to its l-infinite driven version when the goal is to have a tight control on the local reconstruction error.

关键词： l-infinite coding semi-regular mesh compression subdivision-based wavelets

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Scalable joint source and channel coding of meshes

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IEEE TRANSACTIONS ON MUlTIMEDIA 2008年第3期10卷 503-513页

作者： Cernea, Dan C. Munteanu, Adrian Alecu, Alin Cornelis, Jan Schelkens, Peter Vrije Univ Brussel Dept Elect & Informat ETRO Interdisciplinary Inst Broadband Technol IBBT B-1050 Brussels Belgium

This paper proposes a new approach for joint source and channel coding (JSCC) of meshes, simultaneously providing scalability and optimized resilience against transmission errors. An unequal error protection approach is followed, to cope with the different error-sensitivity levels characterizing the various resolution and quality layers produced by the input scalable source codec. The number of layers and the protection levels to be employed for each layer are determined by solving a joint source and channel coding problem. In this context, a novel fast algorithm for solving the optimization problem is conceived, enabling a real-time implementation of the JSCC rate-a I location. An instantiation of the proposed JSCC approach is demonstrated for MeshGrid, which is a scalable 3-D object representation method, part of MPEG-4 AFX. In this context, the l-infinite distortion metric is employed, which is to our knowledge a unique feature in mesh coding. Numerical results show the superiority of the l-infinite norm over the classical l-2 norm in a JSCC setting. One concludes that the proposed joint source and channel coding approach offers resilience against transmission errors, provides graceful degradation, enables a fast real-time implementation, and preserves all the scalability features and animation capabilities of the employed scalable mesh codec.

关键词： error resilient coding joint source and channel coding of meshes l-infinite coding MeshGrid three-dimensional (3-D) graphics unequal error protection

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Unequal error protection of the reference grid for robust transmission of MESHGRID-represented objects over error-prone channels

Unequal error protection of the reference grid for robust tr...

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Conference on Wavelet Applications in Industrial Processing IV

作者： Cernea, Dan C. Munteanu, Adrian Stoufs, Maryse Alecu, Alin Cornelis, Jan Schelkens, Peter Vrije Univ Brussels Dept Elect & Informat ETRO Interdisciplinary Inst Broadband Technol IBBT Pl Laan 2 B-1050 Brussels Belgium

ISBN: (纸本)9780819464811

The heterogeneous nature of modem communications stems from the need of transmitting digital information through various types of mediums to a large variety of end-user terminals. In this context, simultaneously providing a scalable source representation and resilience against transmission errors is of primary importance. MESHGRID, which is part of the MPEG-4 AFX standard, is a scalable 3D object representation method especially designed to address the heterogeneous nature of networks and clients in modem communication systems. A MESHGRID object comprises one or several surface layers attached to and located within a volumetric reference-grid. In this paper we focus on the error-resilience aspects of MESHGRID and propose a novel approach for scalable error-resilient coding of MESHGRID'S reference-grid. An unequal error protection approach is followed, to acquaint for the different effor-sensitivity levels characterizing the various resolution and quality layers produced by the reference-grid coder. The code rates to be employed for each layer are determined by solving a joint source and channel coding problem. The l-infinite distortion metric is employed instead of the classical l-2 norm, typically used in case of images and video. In this context, a novel fast algorithm for solving the optimization problem is proposed. The proposed approach allows for real-time implementations. The experimental results demonstrate the benefits brought by error resilient coding of the reference grid. We conclude that the proposed approach offers resilience against transmission errors while preserving all the scalability features and animation capabilities that characterize MESHGRID.

关键词： 3D graphics MESHGRID error resilient coding of surfaces joint source and channel coding unequal error protection scalable wavelet-based coding l-infinite coding

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