Publications

Book chapters

International Journal Papers

• [43] Influence of Scenarios and Player Traits on Flow in Virtual Reality
  Elise Lavoué, Sophie Villenave, Audrey Serna, Clémentine Didier, Patrick Baert,  Guillaume Lavoué,  IEEE Transactions on Visualization and Computer Graphics, accepted, 2023. [Paper]
• [42] Modeling and hexahedral meshing of cerebral arterial networks from centerlines
  Méghane Decroocq, Carole Frindel, Pierre Rougé, Makoto Ohta, and Guillaume Lavoué, Medical Image Analysis, Volume 89, 102912, 2023. [Paper][Code] 
• [41] Does this virtual food make me hungry? Effects of visual quality and food type in virtual reality
  Florian Ramousse, Pierre Raimbaud, Patrick Baert, Clémentine Helfenstein-Didier, Aurélia Gay, Catherine Massoubre, Bogdan Galusca, and Guillaume Lavoué, Frontiers in Virtual Reality, section Virtual Reality and Human Behaviour, Volume 4, 2023. [Paper]
• [40] SpecTrHuMS: Spectral Transformer for Human Mesh Sequence learning
  Clément Lemeunier, Florence Denis, Guillaume Lavoué, Florent Dupont, Computer & Graphics (Proceedings of 3DOR 2023), Volume 115, Pages 191-203, 2023. Replicability Stamp. [Paper][Code] 
• [39] Crafting the MPEG metrics for objective and perceptual quality assessment of Volumetric Videos
  Jean-Eudes Marvie, Yana Nehmé, Danillo Graziosi, and Guillaume Lavoué, Quality and User Experience (Springer), Volume 8, Article No. 4, 2023. [Paper]
• [38] Textured Mesh Quality Assessment: Large-Scale Dataset and Deep Learning-based Quality Metric
  Yana Nehmé, Johanna Delanoy, Florent Dupont, Jean-Philippe Farrugia, Patrick Le Callet, Guillaume Lavoué, ACM Transactions on Graphics, Volume 42, Issue 3, Article No. 31, pp 1–20, 2023. Presented at SIGGRAPH 2023.[Paper][Supp. Material] [Code] [Dataset].
• [37] Progressive Compression of Triangle Meshes
  Vincent Vidal, Lucas Dubouchet, Guillaume Lavoué, and Pierre Alliez, Image Processing On Line, Volume 13, pp. 1–21, 2023.[Paper] [Code].
• [36] Representation learning of 3D meshes using an Autoencoder in the spectral domain
  Clément Lemeunier, Florence Denis, Guillaume Lavoué, Florent Dupont, Computer & Graphics (Proceedings of 3DOR 2022), Volume 107, Pages 131-143 2022. Best paper award. Replicability Stamp. [Paper] [Code].
• [35] Perceptual Quality of BRDF Approximations: Dataset and Metrics
  Guillaume Lavoué, Nicolas Bonneel, Jean-Philippe Farrugia, Cyril Soler, Computer Graphics Forum (Eurographics 2021), May 2021. [Paper] [Project page] (Copyright Wiley).
• [34] Visual Quality of 3D Meshes with Diffuse Colors in Virtual Reality: Subjective and Objective Evaluation
  Yana Nehmé, Florent Dupont, Jean-Philippe Farrugia, Patrick Le Callet, Guillaume Lavoué,  IEEE Transactions on Visualization and Computer Graphics, vol. 27, no. 3, pp. 2202-2219, 1 March 2021. [Paper] [Code] [dataset] (Copyright IEEE). Replicability Stamp. Presented at IEEE VR 2021.
• [33] Comparison of Subjective Methods for Quality Assessment of 3D Graphics in Virtual Reality
  Yana Nehmé, Jean-Philippe Farrugia, Florent Dupont, Patrick Le Callet, Guillaume Lavoué, ACM Transactions on Applied Perception, Vol. 18, No. 1, Article 2, 23 pages, December 2020. [Paper] [Supp. Material] (Copyright ACM).
• [32] A Psychophysical Evaluation of Texture Compression Masking Effects
  Guillaume Lavoué, Michael Langer, Adrien Peytavie, Pierre Poulin, IEEE Transactions on Visualization and Computer Graphics, Vol. 25, No. 2, Feb. 1, 2019. (Abstract...) [Paper] [Supp. Material] [dataset] (Copyright IEEE)

  Lossy texture compression is increasingly used to reduce GPU memory and bandwidth consumption. However, as raised by recent studies, evaluating the quality of compressed textures is a difficult problem. Indeed using Peak Signal-to-Noise Ratio (PSNR) on texture images, like done in most applications, may not be a correct way to proceed. In particular, there is evidence that masking effects apply when the texture image is mapped on a surface and combined with other textures (e.g., affecting geometry or normal). These masking effects have to be taken into account when compressing a set of texture maps, in order to have a real understanding of the visual impact of the compression artifacts on the rendered images. In this work, we present the first psychophysical experiment investigating the perceptual impact of texture compression on rendered images. We explore the influence of compression bit rate, light direction, and diffuse and normal map content on the visual impact of artifacts. The collected data reveal huge masking effects from normal map to diffuse map artifacts and vice versa, and reveal the weakness of PSNR applied on individual textures for evaluating compression quality. The results allow us to also analyze the performance and failures of image quality metrics for predicting the visibility of these artifacts. We finally provide some recommendations for evaluating the quality of texture compression and show a practical application to approximating the distortion measured on a rendered 3D shape (Hide...)

• [31] Visual Attention for Rendered 3D Shapes
  Guillaume Lavoué, Frédéric Cordier, Hyewon Seo, Mohamed-Chaker Larabi, Computer Graphics Forum (Proceedings of Eurographics 2018),  Vol. 37, No. 2, 2018. (Abstract...) [Paper] [Project page] (Copyright Wiley).

  Understanding the attentional behavior of the human visual system when visualizing a rendered 3D shape is of great importance for many computer graphics applications. Eye tracking remains the only solution to explore this complex cognitive mechanism. Unfortunately, despite the large number of studies dedicated to images and videos, only a few eye tracking experiments have been conducted using 3D shapes. Thus, potential factors that may influence the human gaze in the specific setting of 3D rendering, are still to be understood. In this work, we conduct two eye-tracking experiments involving 3D shapes, with both static and time-varying camera positions. We propose a method for mapping eye fixations (i.e., where humans gaze) onto the 3D shapes with the aim to produce a benchmark of 3D meshes with fixation density maps, which is publicly available. First, the collected data is used to study the influence of shape, camera position, material and illumination on visual attention. We find that material and lighting have a significant influence on attention, as well as the camera path in the case of dynamic scenes. Then, we compare the performance of four representative state-of-the-art mesh saliency models in predicting ground-truth fixations using two different metrics. We show that, even combined with a center-bias model, the performance of 3D saliency algorithms remains poor at predicting human fixations. To explain their weaknesses, we provide a qualitative analysis of the main factors that attract human attention. We finally provide a quantitative comparison of human-eye fixations and Schelling points and show that their correlation is weak. (Hide...)

• [30]  Quality Assessment of 3D Models : on the Influence of Light-Material Interaction 
   Kenneth Vanhoey, Basile Sauvage, Pierre Kraemer, Guillaume Lavoué, ACM Transactions on Applied Perception,  Vol. 15, No. 1, Article 5, October 2017. (Abstract...) [Paper] [Supp. Material] (Copyright ACM).

  Geometric modifications of three-dimensional (3D) digital models are commonplace for the purpose of efficient renderingor compact storage. Modifications imply visual distortions that are hard to measure numerically. They depend not only on the model itself but also on how the model is visualized. We hypothesize that the model’s light environment and the way it reflects incoming light strongly influences perceived quality. Hence, we conduct a perceptual study demonstrating that the same modifications can be masked, or conversely highlighted, by different light-matter interactions. Additionally, we propose a new metric that predicts the perceived distortion of 3D modifications for a known interaction. It operates in the space of 3D meshes with the object’s appearance, that is, the light emitted by its surface in any direction given a known incoming light. Despite its simplicity, this metric outperforms 3D mesh metrics and competes with sophisticated perceptual image-based metrics in terms of correlation to subjective measurements. Unlike image-based methods, it has the advantage of being computable prior to the costly rendering steps of image projection and rasterization of the scene for given camera parameters. (Hide...)

• [29] Subjective and Objective Visual Quality Assessment of Textured 3D Meshes 
  Jinjiang Guo, Vincent Vidal, Irene Cheng, Anup Basu, Atilla Baskurt and Guillaume Lavoué, ACM Transactions on Applied Perception,  Vol. 14, No. 2, Article 11, February 2017. (Abstract...) [Paper] [Supp. Material] [Dataset] (Copyright ACM).

  Objective visual quality assessment of 3D models is a fundamental issue in computer graphics. Quality assessment metrics may allow a wide range of processes to be guided and evaluated, such as level of detail creation, compression, filtering and so on. Most computer graphics assets are composed of geometric surfaces on which several texture images can be mapped to make the rendering more realistic. While some quality assessment metrics exist for geometric surfaces, almost no research has been conducted on the evaluation of texture-mapped 3D models. In this context, we present a new subjective study to evaluate the perceptual quality of textured meshes, based on a paired comparison protocol. We introduce both texture and geometry distortions on a set of 5 reference models to produce a database of 136 distorted models, evaluated using two rendering protocols. Based on analysis of the results, we propose two new metrics for visual quality assessment of textured mesh, as optimized linear combinations of accurate geometry and texture quality measurements. These proposed perceptual metrics outperform their counterparts in terms of correlation with human opinion. The database, along with the associated subjective scores, will be made publicly available on-line. (Hide...)

• [28] Progressive Compression of Arbitrary Textured Meshes  
  Florian Caillaud, Vincent Vidal, Florent Dupont and Guillaume Lavoué, Computer Graphics Forum (Proceedings of Pacific Graphics 2016),  Vol. 35, No. 7, pp. 475-484, 2016. (Abstract...) [Paper] [Supp.  Material] (Copyright Wiley)

  In this paper, we present a progressive compression algorithm for textured surface meshes, which is able to handle polygonal non-manifold meshes as well as discontinuities in the texture mapping. Our method applies iterative batched simplifications, which create high quality levels of detail by preserving both the geometry and the texture mapping. The main features of our algorithm are (1) generic edge collapse and vertex split operators suited for polygonal non-manifold meshes with arbitrary texture seam configurations, and (2) novel geometry-driven prediction schemes and entropy reduction techniques for efficient encoding of connectivity and texture mapping. To our knowledge, our method is the first progressive algorithm to handle polygonal non-manifold models. For geometry and connectivity encoding of triangular manifolds and non-manifolds, our method is competitive with state-of-the-art and even better at low/medium bitrates. Moreover, our method allows progressive encoding of texture coordinates with texture seams; it outperforms state-of-the-art approaches for texture coordinate encoding. We also present a bit-allocation framework which multiplexes mesh and texture refinement data using a perceptually-based image metric, in order to optimize the quality of levels of detail. (Hide...)

• [27] Quality Assessment and Perception in Computer Graphics [Guest Editors' Introduction]
  Guillaume Lavoué, Hantao Liu, Karol Myszkowski, Weisi Lin, IEEE Computer Graphics and Applications, Vol. 36, No. 4, pp. 21-22, 2016. [Paper] (Copyright IEEE)
• [26] On the Efficiency of Image Metrics for Evaluating the Visual Quality of 3D Models
  Guillaume Lavoué, Mohamed Chaker Larabi, Libor Vasa, IEEE Transactions on Visualization and Computer Graphics, Vol. 22, No. 8, pp. 1987-1999, 2016. (Abstract...) [Paper] (Copyright IEEE)

  3D meshes are deployed in a wide range of application processes (e.g. transmission, compression, simplification, watermarking and so on) which inevitably introduce geometric distortions that may alter the visual quality of the rendered data. Hence, efficient model-based perceptual metrics, operating on the geometry of the meshes being compared, have been recently introduced to control and predict these visual artifacts. However, since the 3D models are ultimately visualized on 2D screens, it seems legitimate to use images of the models (i.e. snapshots from different viewpoints) to evaluate their visual fidelity. In this work we investigate the use of image metrics to assess the visual quality of 3D models. For this goal, we conduct a wide-ranging study involving several 2D metrics, rendering algorithms, lighting conditions and pooling algorithms, as well as several mean opinion score databases. The collected data allow (1) to determine the best set of parameters to use for this image-based quality assessment approach and (2) to compare this approach to the best performing model-based metrics and determine for which use-case they are respectively adapted. We conclude by exploring several applications that illustrate the benefits of image-based quality assessment. (Hide...)

• [25] Continuous Semantic Description of 3D Meshes  
  Vincent Léon, Nicolas Bonneel, Guillaume Lavoué, Jean-Philippe Vandeborre, Computers & Graphics (Proceedings of CAD/Graphics 2015), Vol. 54, pp. 47-56, February 2016.  (Abstract...) [Paper] (Copyright Elsevier)

  We propose a novel high-level signature for continuous semantic description of 3D shapes. Given an approximately segmented and labeled 3D mesh, our descriptor consists of a set of geodesic distances to the different semantic labels. This local multidimensional signature effectively captures both the semantic information (and relationships between labels) and the underlying geometry and topology of the shape. We illustrate its benefits on two applications: automatic semantic labeling, seen as an inverse problem along with supervised-learning, and semantic-aware shape editing for which the isocurves of our harmonic description are particularly relevant. (Hide...)

• [24] 3D mesh compression: survey, comparisons and emerging trends  
  Adrien Maglo, Guillaume Lavoué, Florent Dupont and Celine Hudelot, ACM Computing Surveys, Vol. 47, No. 3, Article No. 44, February 2015. (Abstract...) [Paper] (Copyright ACM)

  3D meshes are commonly used to represent virtual surface and volumes. However, their raw data representations take a large amount of space. Hence, 3D mesh compression has been an active research topic since the mid 1990s. In 2005, two very good review articles describing the pioneering works were published. Yet, new technologies have emerged since then. In this article, we summarize the early works and put the focus on these novel approaches. We classify and describe the algorithms, evaluate their performance, and provide synthetic comparisons. We also outline the emerging trends for future research. (Hide...)

• [23] Low budget and high fidelity relaxed 567-remeshing  
  Vincent Vidal, Guillaume Lavoué and Florent Dupont, Computers & Graphics, vol. 47, pp. 16-23, 2015. (Abstract...) [Paper] (Copyright Elsevier)

  567-meshes are a new type of closed and 2-manifold triangular meshes introduced by Aghdaii et al. in 2012 [1]. Valence < 5 or> 7 vertices are problematic for many mesh processing tasks such as edge collapse or surface subdivision. However, valence-6 vertices everywhere is most often impossible due to either surface topology or surface feature preservation, that is why 567-meshes are particularly of interest. This paper proposes a 567-remeshing algorithm that locally retriangulates the mesh considering vertex valence, vertex budget and mesh fidelity as a whole. This algorithm also offers the possibility to preserve a set of feature edges during remeshing. This results in a framework capable of low budget 567-remeshing where remeshed models have a much higher fidelity to the original surface compared to the state of the art. As applications of this work, we demonstrate that our remeshing improves the performances of mesh regularization and progressive mesh compression. (Hide...)

• [22]  Perceptual metrics for static and dynamic triangle meshes  
  Massimiliano Corsini, Mohamed-Chaker Larabi, Guillaume Lavoué, Oldřich Petřík, Libor Váša, Kai Wang, Computer Graphics Forum, vol. 32, No. 1, pp. 101-125, 2013. (Abstract...) [Paper] [Erratum] (Copyright Wiley)

  Almost all mesh processing procedures cause some more or less visible changes in the appearance of objects represented by polygonal meshes. In many cases, such as mesh watermarking, simplification or lossy compression, the objective is to make the change in appearance negligible, or as small as possible, given some other constraints. Measuring the amount of distortion requires taking into account the final purpose of the data. In many applications, the final consumer of the data is a human observer, and therefore the perceptibility of the introduced appearance change by a human observer should be the criterion that is taken into account when designing and configuring the processing algorithms. In this review, we discuss the existing comparison metrics for static and dynamic (animated) triangle meshes. We describe the concepts used in perception-oriented metrics used for 2D image comparison, and we show how these concepts are employed in existing 3D mesh metrics. We describe the character of subjective data used for evaluation of mesh metrics and provide comparison results identifying the advantages and drawbacks of each method. Finally, we also discuss employing the perception-correlated metrics in perception-oriented mesh processing algorithms. (Hide...)

• [21] A comparison of methods for non-rigid 3D shape retrieval
  Zhouhui Lian, Afzal Godil, Benjamin Bustos, Mohamed Daoudi, Jeroen Hermans, Shun Kawamura, Yukinori Kurita, Guillaume Lavoué, Hien Van Nguyen, Ryutarou Ohbuchi, Yuki Ohkita, Yuya Ohishi, Fatih Porikli, Martin Reuter, Ivan Sipiran, Dirk Smeets, Paul Suetens, Hedi Tabia, Dirk Vandermeulen, Pattern Recognition, vol. 46, No. 1, pp. 449-461, 2013.  [Available online] (Copyright Elsevier)
• [20] Combination of bag-of-words descriptors for robust partial shape retrieval  
  Guillaume Lavoué, The Visual Computer, vol. 28, No. 9, pp. 931-942, 2012. (Abstract...) [Paper] (Copyright Springer)

  This paper presents a 3D shape retrieval algorithm based on the Bag of Words (BoW) paradigm. For a given 3D shape, the proposed approach considers a set of feature points uniformly sampled on the surface and associated with local Fourier descriptors; this descriptor is computed in the neighborhood of each feature point by projecting the geometry onto the eigenvectors of the Laplace-Beltrami operator, it is very informative, robust to connectivity and geometry changes and also fast to compute. In a preliminary step, a visual dictionary is built by clustering a large set of feature descriptors, then each 3D shape is described by an histogram of occurrences of these visual words, hence discarding any spatial information. A spatially-sensitive algorithm is also presented where the 3D shape is described by an histogram of pairs of visual words. We show that these two approaches are complementary and can be combined to improve the performance and the robustness of the retrieval. The performances have been compared against very recent state-of-the-art methods on several different datasets. For global shape retrieval our combined approach is comparable to these recent works, however it clearly outperforms them in the case of partial shape retrieval. . (Hide...)

• [19] Rate-distortion optimization for progressive compression of 3D mesh with color attributes  
  Ho Lee, Guillaume Lavoué and Florent Dupont, The Visual Computer, vol. 28, No. 2, pp. 137-153, 2012. (Abstract...) [Paper] [Code] (Copyright Springer)

  We propose a new lossless progressive compression algorithm based on rate-distortion optimization for meshes with color attributes; the quantization precision of both the geometry and the color information is adapted to each intermediate mesh during the encoding/decoding process. This quantization precision can either be optimally determined with the use of a mesh distortion measure or be quasi-optimally decided based on an analysis of the mesh complexity in order to reduce the calculation time. Furthermore, we propose a new metric which estimates the geometry and color importance of each vertex during the simplification in order to preserve faithfully the feature elements. Experimental results show that our method outperforms the state-of-the-art algorithm for colored meshes and competes with the most efficient algorithms for non colored meshes. (Hide...)

• [18] Assessing Visual Quality of 3D Polygonal Models
  Abdullah Bulbul, Tolga Capin, Guillaume Lavoué , Marius Preda, IEEE Signal Processing Magazine, vol. 28, No. 6, pp. 80-90, 2011.(Abstract...) [Preprint] (Copyright IEEE)

  This survey paper presents recent advances in evaluating and measuring the perceived visual quality of 3D polygonal models. The paper analyzes the general process of objective quality assessment metrics and subjective user evaluation methods and presents a taxonomy of existing solutions. Simple geometric error computed directly on the 3D models does not necessarily reflect the perceived visual quality; therefore, integrating perceptual issues for 3D quality assessment is of great significance. This paper discusses existing metrics, including perceptually based ones, computed either on 3D data or on 2D projections, and evaluates their performance for their correlation with existing subjective studies. (Hide...)

• [17] Learning boundary edges for 3D-mesh segmentation  
  Halim Benhabiles,  Guillaume Lavoué, Jean-Philippe Vandeborre and Mohamed Daoudi, Computer Graphics Forum (selected for presentation at Eurographics 2012), vol. 30, No. 8, pp. 2170-2182, 2011. (Abstract...) [Paper] [Material] (Copyright Wiley)

  This paper presents a 3D-mesh segmentation algorithm based on a learning approach. A large database of manually segmented 3D-meshes is used to learn a boundary edge function. The function is learned using a classifier which automatically selects from a pool of geometric features the most relevant ones to detect candidate boundary edges. We propose a processing pipeline that produces smooth closed boundaries using this edge function. This pipeline successively selects a set of candidate boundary contours, closes them and optimizes them using a snake movement. Our algorithm was evaluated quantitatively using two different segmentation benchmarks and was shown to outperform most recent algorithms from the state-of-the-art. (Hide...)

• [16] A Multiscale Metric for 3D Mesh Visual Quality Assessment  
  Guillaume Lavoué, Computer Graphics Forum (Proceedings of Eurographics Symposium on Geometry Processing 2011), vol. 30, No. 5, pp. 1427-1437, 2011. (Abstract...) [Paper] [Code] (Copyright Wiley) [Erratum]

  Many processing operations are nowadays applied on 3D meshes like compression, watermarking, remeshing and so forth; these processes are mostly driven and/or evaluated using simple distortion measures like the Hausdorff distance and the root mean square error, however these measures do not correlate with the human visual perception while the visual quality of the processed meshes is a crucial issue. In that context we introduce a full-reference 3D mesh quality metric; this metric can compare two meshes with arbitrary connectivity or sampling density and produces a score that predicts the distortion visibility between them; a visual distortion map is also created. Our metric outperforms its counterparts from the state of the art, in term of correlation with mean opinion scores coming from subjective experiments on three existing databases. Additionally, we present an application of this new metric to the improvement of rate-distortion evaluation of recent progressive compression algorithms. . (Hide...)

• [15] Joint Reversible Watermarking and Progressive Compression of 3D Meshes  
  Ho Lee, Cagatay Dikici, Guillaume Lavoué and Florent Dupont, The Visual Computer (35 best papers from Computer Graphics International 2011), vol. 27, No. 6-8, pp. 781-792, 2011. (Abstract...) [Paper] [Code] (Copyright Springer)

  A new reversible 3D mesh watermarking scheme is proposed in conjunction with progressive compression. Progressive 3D mesh compression permits a progressive refinement of the model from a coarse to a fine representation by using different levels of detail (LoDs). A reversible watermark is embedded into all reffinement levels such that (1) the reffinement levels are copyright protected, and (2) an authorized user is able to reconstruct the original 3D model after watermark extraction, hence reversible. The progressive compres- sion considers a connectivity-driven algorithm to choose the vertices that are to be refined for each LoD. The proposed watermarking algorithm modifies the geom- etry information of these vertices based on histogram bin shifting technique. An authorized user can extract the watermark in each LoD and recover the original 3D mesh, while an unauthorized user which has access to the decompression algorithm can only reconstruct a distorted version of the 3D model. Experimental results show that the proposed method is robust to several at- tack scenarios while maintaining a good compression ratio. (Hide...)

• [14]  Robust and blind mesh watermarking based on volume moments
  Kai Wang, Guillaume Lavoué, Florence Denis and Atilla Baskurt, Computers & Graphics, Vol. 35, No. 1, pp. 1-19, 2011. (Abstract...) [Paper] (Copyright Elsevier)

  This paper presents a robust and blind watermarking algorithm for threedimensional (3D) meshes. The watermarking primitive is an intrinsic 3D shape descriptor: the analytic and continuous geometric volume moment. During watermark embedding, the input mesh is first normalized to a canonical and robust spatial pose by using its global volume moments. Then, the normalized mesh is decomposed into patches and the watermark is embedded through a modified scalar Costa quantization of the zero-order volume moments of some selected candidate patches. Experimental results and comparisons with the state of the art demonstrate the effectiveness of the proposed approach. . (Hide...)

• [13] A comparison of perceptually-based metrics for objective evaluation of geometry processing
  Guillaume Lavoué and Massimiliano Corsini, IEEE Transactions on Multimedia, Vol. 12, No. 7, pp. 636-649, 2010. (Abstract...) [Paper] [Datasets] [Code] (Copyright IEEE) [Erratum]

  Recent advances in 3D graphics technologies have led to an increasing use of processing techniques on 3D meshes, such as filtering, compression, watermarking, simplification, deformation and so forth. Since these processes may modify the visual appearance of the 3D objects, several metrics have been introduced so as to properly drive or evaluate them, from classic geometric ones such as Hausdorff distance, to more complex perceptually-based measures. This paper presents a survey on existing perceptually-based metrics for visual impairment of 3D objects and provides an extensive comparison between them. In particular, different scenarios which correspond to different perceptual and cognitive mechanisms are analyzed. The objective is twofold: (1) catching the behavior of existing measures so as to help Perception researchers for designing new 3D metrics and (2) providing a comparison between them so as to inform and help Computer Graphics researchers for choosing the accurate tool for the design and the evaluation of their mesh processing algorithms. (Hide...)

• [12] A comparative study of existing metrics for 3D-mesh segmentation evaluation
  Halim Benhabiles, Jean-Philippe Vandeborre, Guillaume Lavoué and Mohamed Daoudi, The Visual Computer, Vol. 26, No. 12, pp. 1451–1466, 2010. (Abstract...) [Paper] [Benchmark] (Copyright Springer)

  In this paper, we present an extensive experimental comparison of existing similarity metrics addressing the quality assessment problem of mesh segmentation. We introduce a new metric named the 3D Normalized Probabilistic Rand Index (3D-NPRI) which outperforms the others in terms of properties and discriminative power. This comparative study includes a subjective experiment with human observers and is based on a corpus of manually segmented models. This corpus is an improved version of our previous one~\cite{benhabiles09}. It is composed of a set of 3D-mesh models grouped in different classes associated with several manual ground-truth segmentations. Finally the 3D-NPRI is applied to evaluate six recent segmentation algorithms using our corpus and the Chen's et al.~\cite{chen09} corpus. (Hide...)

• [11] Semi-Sharp Subdivision Surface Fitting Based on Feature Lines Approximation
  Guillaume Lavoué and Florent Dupont, Computers & Graphics, Vol. 33, No. 2, pp. 151-161, 2009. (Abstract...) [video] [Paper] (Copyright Elsevier)

  This paper presents an algorithm for approximating arbitrary polygonal meshes with subdivision surfaces, with the objective of preserving the relevant features of the object while searching the coarsest possible control mesh. The main idea is to firstly extract the feature lines of the object, and secondly construct the subdivision surface over this network. Control points are created by approximating these lines while the connectivity is built with respect to the anisotropy of the object. Our algorithm reinforces the similarity between the subdivision surface and the original shape by affecting an integer sharpness degree to each control edge in order to accurately reproduce the different curvature radii of corresponding fillets and blends. (Hide...)

• [10] A Local Roughness Measure for 3D Meshes and its Application to Visual Masking
  Guillaume Lavoué, ACM Transactions on Applied Perception, Vol. 5, No. 4, Article 21, 2009. (Abstract...) [exe] [Paper] (Copyright ACM)

  3D models are subject to a wide variety of processing operations such as compression, simplification or watermarking, which may introduce some geometric artifacts on the shape. The main issue is to maximize the compression/simplification ratio or the watermark strength while minimizing these visual degradations. However few algorithms exploit the human visual system to hide these degradations, while perceptual attributes could be quite relevant for this task. Particularly, the masking effect defines the fact that one visual pattern can hide the visibility of another. In this context we introduce an algorithm for estimating the roughness of a 3D mesh, as a local measure of geometric noise on the surface. Indeed, a textured (or rough) region is able to hide geometric distortions much better than a smooth one. Our measure is based on curvature analysis on local windows of the mesh and is independent of the resolution/connectivity of the object. The accuracy and the robustness of our measure, together with its relevance regarding visual masking have been demonstrated through extensive comparisons with state-of-the-art and subjective experiment. Two applications are also presented, in which the roughness is used to lead (and improve) respectively compression and watermarking algorithms. (Hide...)

• [9] Improving Zernike Moments Comparison for Optimal Similarity and Rotation Angle Retrieval
  Jérôme Revaud, Guillaume Lavoué and Atilla Baskurt, IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 31, No. 4, pp. 627-636, 2009. (Abstract...) [Paper] (Copyright IEEE)

  Zernike moments constitute a powerful shape descriptor in terms of robustness and description capability. However the classical way of comparing two Zernike descriptors only takes into account the magnitude of the moments and loses the phase information. The novelty of our approach is to take advantage of the phase information in the comparison process while still preserving the invariance to rotation. This new Zernike comparator provides a more accurate similarity measure together with the optimal rotation angle between the patterns, while keeping the same complexity as the classical approach. This angle information is particularly of interest for many applications, including 3D scene understanding through images. Experiments demonstrate that our comparator outperforms the classical one in terms of similarity measure. In particular the robustness of the retrieval against noise and geometric deformation is greatly improved. Moreover, the rotation angle estimation is also more accurate than state of the art algorithms. (Hide...)

• [8] Hierarchical Watermarking of Semi-regular Meshes Based on Wavelet Transform
  Kai Wang, Guillaume Lavoué, Florence Denis and Atilla Baskurt, IEEE Transactions on Information Forensics and Security, Vol. 3, No. 4, pp. 620-634, 2008. (Abstract...) [Paper] (Copyright IEEE)

  This paper presents a hierarchical watermarking framework for semi-regular meshes. Three blind watermarks are inserted in a semi-regular mesh with different purposes: a geometrically robust watermark for copyright protection, a highcapacity watermark for carrying a large amount of auxiliary information, and a fragile watermark for content authentication. The proposed framework is based on wavelet transform of the semi-regular mesh. More precisely, the three watermarks are inserted in different appropriate resolution levels obtained by wavelet decomposition of the mesh: the robust watermark is inserted by modifying the norms of the wavelet coefficient vectors associated with the lowest resolution level; the fragile watermark is embedded in the high resolution level obtained just after one wavelet decomposition by modifying the orientations and norms of the wavelet coefficient vectors; the high-capacity watermark is inserted in one or several intermediate levels by considering groups of wavelet coefficient vector norms as watermarking primitives. Experimental results demonstrate the effectiveness of the proposed framework: the robust watermark is able to resist all the common geometric attacks even with relatively strong amplitude; the fragile watermark is robust to contentpreserving operations, while sensitive to other attacks of which it can also provide the precise location; the payload of the highcapacity watermark increases rapidly along with the number of watermarking primitives. (Hide...)

• [7] A Comprehensive Survey on Three-Dimensional Mesh Watermarking
  Kai Wang, Guillaume Lavoué, Florence Denis and Atilla Baskurt, IEEE Transactions on Multimedia, Vol. 10, No.8, pp. 1513-1527, 2008. (Abstract...) [Paper] (Copyright IEEE)

  Three-dimensional meshes have been used more and more in industrial, medical and entertainment applications during the last decade. Many researchers, from both the academic and the industrial sectors, have become aware of their intellectual property protection and authentication problems arising with their increasing use. This paper gives a comprehensive survey on 3D mesh watermarking, which is considered an effective solution to the above two emerging problems. Our survey covers an introduction to the relevant state of the art, an attack-centric investigation, and a list of existing problems and potential solutions. First, the particular difficulties encountered while applying watermarking on 3D meshes are discussed, followed by a presentation and an analysis of the existing algorithms, distinguishing them between fragile techniques and robust techniques. Since the attacks play an important role in the design of 3D mesh watermarking algorithms, we also provide an attack-centric viewpoint of this state of the art. Finally, some future working directions are pointed out especially on the ways of devising robust and blind algorithms and on some new probably promising watermarking feature spaces. . (Hide...)

• [6] Subdivision surface watermarking
  Guillaume Lavoué, Florence Denis and Florent Dupont, Computers & Graphics, Vol. 31, No.3, pp. 480-492, 2007. (Abstract...) [Paper] (Copyright Elsevier)

  This paper presents a robust non-blind watermarking scheme for subdivision surfaces. The algorithm works in the frequency domain, by modulating spectral coefficients of the subdivision control mesh. The compactness of the watermarking support (a coarse control mesh) has led us to optimize the trade-off between watermarking redundancy (which insures robustness) and imperceptibility by introducing two contributions: (1) Spectral coefficients are perturbed according to a new modulation scheme analysing the spectrum shape and (2) the redundancy is optimized by using error correcting codes coming from telecommunication theory. Since the watermarked surface can be attacked in a subdivided version, we have introduced an algorithm to retrieve the control polyhedron, starting from a subdivided, attacked version. Experiments have shown the high robustness of our scheme against geometry attacks such as noise addition, quantization or non-uniform scaling and also connectivity alterations such as remeshing or simplification. (Hide...)

• [5] A framework for quad/triangle subdivision surface fitting:  Application to mechanical objects 
  Guillaume Lavoué, Florent Dupont and Atilla Baskurt, Computer Graphics Forum, Vol. 26, No.1, pp. 1-14, 2007. (Abstract...) [Paper] (Copyright Wiley)

  In this paper we present a new framework for subdivision surface approximation of 3D models represented by polygonal meshes. Our approach, particularly suited for mechanical or CAD parts, produces a mixed quadrangle-triangle control mesh, optimized in terms of face and vertex numbers while remaining independent of the connectivity of the input mesh. Our algorithm begins with a decomposition of the object into surface patches. Then the main idea is to approximate first the region boundaries and then the interior data. Thus, for each patch, a first step approximates the boundaries with subdivision curves (associated with control polygons) and creates an initial subdivision surface by linking the boundary control points with respect to the lines of curvature of the target surface. Then, a second step optimizes the initial subdivision surface by iteratively moving control points and enriching regions according to the error distribution. The final control mesh defining the whole model is then created assembling every local subdivision control meshes. This control polyhedron is much more compact than the original mesh and visually represents the same shape after several subdivision steps, hence it is particularly suitable for compression and visualization tasks. Experiments conducted on several mechanical models have proven the coherency and the efficiency of our algorithm, compared with existing methods. (Hide...)

• [4] High rate compression of CAD meshes based on subdivision inversion
  Guillaume Lavoué, Florent Dupont and Atilla Baskurt, Annals of Telecommunications, Vol. 60, No.11-12, pp. 1286-1310, 2005. (Abstract...) [Paper]

  In this paper we present a new framework, based on subdivision surface approximation, for efficient compression and coding of 3D models represented by polygonal meshes. Our algorithm fits the input 3D model with a piecewise smooth subdivision surface represented by a coarse control polyhedron, near optimal in terms of control points number and connectivity. Our algorithm, which remains independent of the connectivity of the input mesh, is particularly suited for meshes issued from mechanical or CAD parts. The found subdivision control polyhedron is much more compact than the original mesh and visually represents the same shape after several subdivision steps, without artifacts or cracks, like traditional lossy compression schemes. This control polyhedron is then encoded specifically to give the final compressed stream. Experiments conducted on several CAD models have proven the coherency and the efficiency of our algorithm, compared with existing methods. (Hide...)

• [3] A new subdivision based approach for piecewise smooth approximation of 3D polygonal curves
  Guillaume Lavoué, Florent Dupont and Atilla Baskurt, Pattern Recognition, Vol. 38, No.8, pp. 1139-1151, 2005. (Abstract...) [Paper] (Copyright Elsevier)

  This paper presents an algorithm dealing with the data reduction and the approximation of 3D polygonal curves. Our method is able to approximate efficiently a set of straight 3D segments or points with a piecewise smooth subdivision curve, in a near optimal way in terms of control point number. Our algorithm is a generalization for subdivision rules, including sharp vertex processing, of the Active B-Spline Curve developed by Pottmann et al. We have also developed a theoretically demonstrated approach, analysing curvature properties of B-Splines, which computes a near optimal evaluation of the initial number and positions of control points. Moreover, our original Active Footpoint Parameterization method prevents wrong matching problems occurring particularly for self-intersecting curves. Thus, the stability of the algorithm is highly increased. Our method was tested on different sets of curves and gives satisfying results regarding to approximation error, convergence speed and compression rate. This method is in line with a larger 3D CAD object compression scheme by piecewise subdivision surface approximation. The objective is to fit a subdivision surface on a target patch by first fitting its boundary with a subdivision curve whose control polygon will represent the boundary of the surface control polyhedron.(Hide...)

• [2] A new CAD mesh segmentation method, based on curvature tensor analysis
  Guillaume Lavoué, Florent Dupont and Atilla Baskurt, Computer Aided Design, Vol. 37, No. 10, pp. 975-987, 2005. (Abstract...) [Paper] (Copyright Elsevier)

  This paper presents a new and efficient algorithm for the decomposition of 3D arbitrary triangle meshes and particularly optimized triangulated CAD meshes. The algorithm is based on the curvature tensor field analysis and presents two distinct complementary steps: a region based segmentation, which is an improvement of that presented by Lavoue et al. [Lavoue G, Dupont F, Baskurt A. Constant curvature region decomposition of 3D-meshes by a mixed approach vertex-triangle, J WSCG 2004;12(2):245–52] and which decomposes the object into near constant curvature patches, and a boundary rectification based on curvature tensor directions, which corrects boundaries by suppressing their artefacts or discontinuities. Experiments conducted on various models including both CAD and natural objects, show satisfactory results. Resulting segmented patches, by virtue of their properties (homogeneous curvature, clean boundaries) are particularly adapted to computer graphics tasks like parametric or subdivision surface fitting in an adaptive compression objective. (Hide...)

• [1] Object of Interest based visual navigation, retrieval and semantic content identification system 
  Khalid Idrissi, Guillaume Lavoué, Julien Ricard and Atilla Baskurt, Computer Vision and Image Understanding, Vol. 94, No. 1-3, pp. 271-294, 2004. (Abstract...) [Paper] (Copyright Elsevier)
  

  This study presents a content-based image retrieval system IMALBUM based on local region of interest called object of interest (OOI). Each segmented or user-selected OOI is indexed with new local adapted descriptors associated to color, texture, and shape features. This local approach is an efficient way to associate the local semantic content with low-level descriptors (color, texture, shape, etc.) computed on regions selected by the user. So the user actively takes part in the indexing process (offline) and can use a selected OOI as a query for the retrieval system (online). The IMALBUM system proposes original functionalities. A visual navigation tool allows to surf in the image database when the user has no precise idea of what he is really searching for in the database. Furthermore, when an OOI is selected as a query for retrieval, a semantic content identification tool indicates to the user the probable class of this unknown object. The performance of these different tools are evaluated on different databases.(Hide...)

International conferences

• [61] Immersive Multisensory Digital Twins: concept, methods and case study
  Charles Javerliat, Pierre Raimbaud, Sophie Villenave, Pierre-Philippe Elst, Eliott Zimmermann, Martin Guesney, Mylène Pardoen, Patrick Baert, and Guillaume Lavoué, Workshop on Multisensory Experiences (SENSORYX '23), At ACM IMX 2023. [paper]
• [60] ReVBED: A semi-guided virtual environment for inducing food craving in a binge-eating therapy process
  Florian Ramousse, Guillaume Lavoué, Patrick Baert, Vikesh Bhoowabul, Séverine Fleury, Baptiste Ravey, Aurélia Gay, Catherine Massoubre, and Clémentine Helfenstein-Didier, CARE IMX Workshop , At ACM IMX 2023. [paper]
• [59] Adaptive streaming of 3D content for web-based virtual reality:  an open-source prototype including several metrics and strategies
  Jean-Philippe Farrugia, Luc Billaud, Guillaume Lavoué, ACM Multimedia Systems Conference (MMSys) 2023 - Open Dataset & Software track. [paper] [code]
• [58] Nebula: An Affordable Open-Source and Autonomous Olfactory Display for VR Headsets
  Charles Javerliat, Pierre-Philippe Elst, Anne-Lise Saive, Patrick Baert, Guillaume Lavoué, ACM Symposium on Virtual Reality Software and Technology (VRST), November 2022. [paper] [code & materials]  (Copyright ACM)
• [57] A Software to Visualize, Edit, Model and Mesh Vascular Networks
  M&eacuteghane Decroocq, Guillaume Lavoué, Makoto Ohta, Carole Frindel,  International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), July 2022. [paper] [code]. (Copyright IEEE) 
• [56] XREcho: A Unity plug-in to record and visualize user behavior during XR sessions
  Sophie Villenave, Jonathan Cabezas, Patrick Baert, Florent Dupont, Guillaume Lavoué, ACM Multimedia Systems Conference (MMSys), June 2022. [paper] [code] (Copyright ACM).
• [55] Exploring Crowdsourcing for Subjective Quality Assessment of 3D Graphics
  Yana Nehmé, Patrick Le Callet, Florent Dupont, Jean-Philippe Farrugia, Guillaume Lavoué, IEEE International Workshop on Multimedia Signal Processing (MMSP), 2021. [paper]
• [54] CMDM-VAC: Improving A Perceptual Quality Metric For 3D Graphics By Integrating A Visual Attention Complexity Measure 
  Yana Nehmé, Mona Abid, Guillaume Lavoué, Matthieu Perreira Da Silva, Patrick Le Callet, IEEE International Conference on Image Processing (ICIP), 2021. [Paper] (Copyright IEEE) 
• [53] PCQM: A full-reference quality metric for colored 3D point clouds 
  Gabriel Meynet, Yana Nehmé, Julie Digne, Guillaume Lavoué, International Conference on Quality of Multimedia Experience (QoMEX), 2020. [Paper] [Code] [(Copyright IEEE) Best Student Paper Award.
• [52] MEPP2: a generic platform for processing 3D meshes and point clouds 
  Vincent Vidal, Eric Lombardi, Martial Tola, Florent Dupont, Guillaume Lavoué, Eurographics 2020, short paper program. [Paper] [website] (Copyright Eurographics)
• [51] Comparison of subjective methods, with and without explicit reference, for quality assessment of 3D graphics
  Yana Nehmé, Jean-Philippe Farrugia, Florent Dupont, Patrick Le Callet, Guillaume Lavoué, ACM Symposium on Applied Perception (SAP), Barcelona, Spain, September 2019. (Abstract...) [Preprint] [Supp. Material] (Copyright ACM).

  Numerous methodologies for subjective quality assessment exist in the field of image processing. In particular, the Absolute Category Rating with Hidden Reference (ACR-HR) and the Double Stimulus Impairment Scale (DSIS) are considered two of the most prominent methods for assessing the visual quality of 2D images and videos. Are these methods valid/accurate to evaluate the perceived quality of 3D graphics data? Is the presence of an explicit reference necessary, due to the lack of human prior knowledge on 3D graphics data compared to natural images/videos? To answer these questions, we compare these two subjective methods (ACR-HR and DSIS) on a dataset of high-quality colored 3D models, impaired with various distortions. These subjective experiments were conducted in a virtual reality (VR) environment. Our results show differences in the performance of the methods depending on the 3D contents and the types of distortions. We show that DSIS outperforms ACR-HR in term of accuracy and points out a stable performance. Results also yield interesting conclusions on the importance of a reference for judging the quality of 3D graphics. We finally provide recommendations regarding the influence of the number of observers on the accuracy. (Hide...)

• [50] Factors to Consider for Tailored Gamification
  Stuart Hallifax, Audrey Serna, Jean-Charles Marty, Guillaume Lavoué, Elise Lavoué, ACM SIGCHI Annual Symposium on Computer-Human Interaction in Play (CHI PLAY), Barcelona, Spain, October 2019. [Preprint] (Copyright ACM). Honorable Mention Award.
• [49] PC-MSDM: A quality metric for 3D point clouds 
  Gabriel Meynet, Julie Digne, Guillaume Lavoué, International Conference on Quality of Multimedia Experience (QoMEX), short paper, Berlin, Germany, 2019. (Abstract...) [Paper] [Code] [(Copyright IEEE)

  In this paper, we present PC-MSDM, an objective metric for visual quality assessment of 3D point clouds. This full-reference metric is based on local curvature statistics and can be viewed as an extension for point clouds of the MSDM metric suited for 3D meshes. We evaluate its performance on an open subjective dataset of point clouds compressed by octree pruning; results show that the proposed metric outperforms its counterparts in terms of correlation with mean opinion scores. (Hide...)

• [48] Least Squares Affine Transitions for Global Parameterization  
  Ana Vintescu, Florent Dupont, Guillaume Lavoue, Pooran Memari, Julien Tierny, International Conference on Computer Graphics, Visualization and Computer Vision (WSCG), , Plzen, Czech Republic, June 2017. (Abstract...) [Paper] 

  This paper presents an efficient algorithm for a global parameterization of triangular surface meshes. In contrast to previous techniques which achieve global parameterization through the optimization of non-linear systems of equations, our algorithm is solely based on solving at most two linear equation systems, in the least square sense. Therefore, in terms of running time the unfolding procedure is highly efficient. Our approach is direct – it solves for the planar UV coordinates of each vertex directly – hence avoiding any numerically challenging planar recon- struction in a post-process. This results in a robust unfolding algorithm. Curvature prescription for user-provided cone singularities can either be specified manually, or suggested automatically by our approach. Experiments on a variety of surface meshes demonstrate the runtime efficiency of our algorithm and the quality of its unfolding. To demonstrate the utility and versatility of our approach, we apply it to seamless texturing. The proposed algorithm is computationally efficient, robust and results in a parameterization with acceptable metric distortion. (Hide...)

• [47] Conformal Factor Persistence for Fast Hierarchical Cone Extraction  
  Ana Vintescu, Florent Dupont, Guillaume Lavoue, Pooran Memari, Julien Tierny, Eurographics 2017, short paper program, Lyon, France, 2017. (Abstract...) [Paper] (Copyright Eurographics)

  This paper presents a new algorithm for the fast extraction of hierarchies of cone singularities for conformal surface parameterization.Cone singularities have been shown to greatly improve the distortion of such parameterizations since they locally absorb the area distortion. Therefore, existing automatic approaches aim at inserting cones where large area distortion can be predicted. However, such approaches are iterative, which results in slow computations, even often slower than the actual subsequent parameterization procedure. This becomes even more problematic as often the user does not know in advance the right number of needed cones and thus needs to explore cone hierarchies to obtain a satisfying result. Our algorithm relies on the key observation that the local extrema of the conformal factor already provide a good approximation of the cone singularities extracted with previous techniques, while needing only one linear solving where previous approaches needed one solving per hierarchy level. We apply concepts from persistent homology to organize very efficiently such local extrema into a global hierarchy. Experiments demonstrate the approximation quality of our approach quantitatively and report time-performance improvements of one order of magnitude, which makes our technique well suited for interactive contexts. (Hide...)

• [46] Semantic correspondence across 3D models for example-based modeling  
  Vincent Léon, Vincent Itier, Nicolas Bonneel, Guillaume Lavoué, Jean-Philippe Vandeborre, Eurographics Workshop on 3D Object Retrieval (3DOR), Lyon, France, 2017. (Abstract...) [Paper] (Copyright Eurographics)

  Modeling 3D shapes is a specialized skill not affordable to most novice artists due to its complexity and tediousness. At the sametime, databases of complex models ready for use are becoming widespread, and can help the modeling task in a process called example-based modeling. We introduce such an example-based mesh modeling approach which, contrary to prior work, allows for the replacement of any localized region of a mesh by a region of similar semantics (but different geometry) within a mesh database. For that, we introduce a selection tool in a space of semantic descriptors that co-selects areas of similar semantics within the database. Moreover, this tool can be used for part-based retrieval across the database. Then, we show how semantic information improves the assembly process. This allows for modeling complex meshes from a coarse geometry and a database of more detailed meshes, and makes modeling accessible to the novice user. (Hide...)

• [45] Progressive streaming of textured 3D models in a web browser
  Guillaume Lavoué, Laurent Chevalier, Florian Caillaud and Florent Dupont, ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games, Poster, Redmond, US, February 2016. [Paper]
• [44] Efficient Decomposition of Image and Mesh Graphs by Lifted Multicuts  
  Margret Keuper, Evgeny Levinkov, Nicolas Bonneel, Guillaume Lavoué, Thomas Brox, Bjoern Andres, IEEE International Conference on Computer Vision (ICCV), Santiago, Chile, December 2015.(Abstract...) [Video] [Paper] (Copyright IEEE)

  Formulations of the Image Decomposition Problem [8] as a Multicut Problem (MP) w.r.t. a superpixel graph have received considerable attention. In contrast, instances of the MP w.r.t. a pixel grid graph have received little attention, firstly, because the MP is NP-hard and instances w.r.t. a pixel grid graph are hard to solve in practice, and, secondly, due to the lack of long-range terms in the objective function of the MP. We propose a generalization of the MP with longrange terms (LMP). We design and implement two efficient algorithms (primal feasible heuristics) for the MP and LMP which allow us to study instances of both problems w.r.t. the pixel grid graphs of the images in the BSDS-500 benchmark [8]. The decompositions we obtain do not differ significantly from the state of the art, suggesting that the LMP is a competitive formulation of the Image Decomposition Problem. To demonstrate the generality of the LMP, we apply it also to the Mesh Decomposition Problem posed by the Princeton benchmark [16], obtaining state-of-the-art decompositions. (Hide...)

• [43] Evaluating the local visibility of geometric artifacts 
  Jinjiang Guo, Vincent Vidal, Atilla Baskurt and Guillaume Lavoué, ACM Symposium on Applied Perception, Tubingen, Germany, September 2015. (Abstract...) [Paper] [Supp. Material] [Dataset] (Copyright ACM).

  Several perceptually-based quality metrics have been introduced to predict the global impact of geometric artifacts on the visual appearance of a 3D model. They usually produce a single score that reflects the global level of annoyance caused by the distortions. However, beside this global information, it is also important in many applications to obtain information about the local visibility of the artifacts (i.e. estimating a localized distortion measure). In this work we present a psychophysical experiment where observers are asked to mark areas of 3D meshes that contain noticeable distortions. The collected per-vertex distortion maps are first used to illustrate several perceptual mechanisms of the human visual system. They then serve as ground-truth to evaluate the performance of well-known geometric attributes and metrics for predicting the visibility of artifacts. Results show that curvature-based attributes demonstrate excellent performance. As expected, the Hausdorff distance is a poor predictor of the perceived local distortion while the recent perceptually-based metrics provide the best results. (Hide...)

• [42] Progressive compression of generic surface meshes 
  Florian Caillaud, Vincent Vidal, Florent Dupont and Guillaume Lavoué, Computer Graphics International, Short paper, Strasbourg, France, June 2015. (Abstract...) [Paper]

  This paper presents a progressive compression method for generic surface meshes (non-manifold and/or polygonal). Two major contributions are proposed : (1) generic edge collapse and vertex split operators allowing surface simplification and refinement of a mesh, whatever its connectivity; (2) a distortion-aware collapse clustering strategy that adapts the decimation granularity in order to optimize the rate-distortion tradeoff. (Hide...)

• [41] Progressive Streaming of Compressed 3D Graphics in a Web Browser
  Guillaume Lavoué, Laurent Chevalier, Florent Dupont, ACM SIGGRAPH 2014 - Talk Program, Vancouver, Canada, August 2014. [Paper]  [Video] (Copyright ACM).
• [40] Perceptual Quality Metrics for 3D Meshes: Towards an Optimal Multi-Attribute Computational Model
  Guillaume Lavoué , Irene Cheng, Anup Basu, IEEE International Conference on Systems, Man, and Cybernetics (SMC), Manchester, UK, October 2013. (Abstract...) [Paper] (Copyright IEEE)

  3D graphical data, commonly represented using triangular meshes, are deployed in a wide range of application processes including compression, filtering, watermarking, and simplification. These processes often introduce geometric distortions which affect the visual quality of the ultimate data visualization. In order to accurately evaluate perceptual impacts caused by the distortions, assessment metrics on 3D Mesh Visual Quality (MVQ) have been extensively discussed in the literature. Researchers recommended various metrics to predict the adverse effects that visual artifacts can have in applications. Most of these metrics are based on geometric attributes, \eg conventional geometric distance, Laplacian coordinates, different types of curvature computation, and dihedral angles. We hypothesize that an optimal combination of multiple attributes associated with a 3D mesh surface can contribute to better perceptual prediction than single attributes used separately. In this paper, we use two user studies to validate our hypothesis. Our contributions are: (1) providing a detailed analysis of the most relevant geometric attributes for mesh quality assessment, and (2) introducing a new perceptual evaluation metric based on multiple attributes, with the optimal combination determined through machine learning techniques. Statistical quantitative analysis shows that our metric delivers better results than other state-of-the-art approaches. The proposed method is simple to implement and fast in execution. Moreover, our framework can easily be expanded to accommodate additional surface attributes. (Hide...)

• [39] Evaluation of 3D Model Segmentation Techniques based on Animal Anatomy
  Nasim Hajari, Irene Cheng, Anup Basu, Guillaume Lavoué, IEEE International Conference on Systems, Man, and Cybernetics (SMC), Manchester, UK, October 2013. (Abstract...) [Paper] (Copyright IEEE)

  3D model decomposition is a challenging and important problem in computer graphics. Several semantically based approaches have been proposed in the literature; however, due to the lack of proper evaluation criteria, comparison of these techniques is almost impossible. In this paper we suggest to use animal anatomy as the ground truth and compare the result of different segmentation techniques based on that. Differing from previous approaches which perform the evaluation based on ground truth databases created subjectively by human observers, we consider expert knowledge on anatomy of various animals. Based on this knowledge we specify the ground truth for different animals and compare alternative algorithms. (Hide...)

• [38] Streaming Compressed 3D Data on the Web using JavaScript and WebGL  
  Guillaume Lavoué, Laurent Chevalier, Florent Dupont, International Conference on 3D Web Technology (Web3D), San Sebastian, Spain, June 2013. (Abstract...) [Paper]  [Video] (Copyright ACM)

  With the development of Web3D technologies, the delivery and visualization of 3D models on the web is now possible and is bound to increase both in the industry and for the general public. However the interactive remote visualization of 3D graphic data in a web browser remains a challenging issue. Indeed, most of existing systems suffer from latency (due to the data downloading time) and lack of adaptation to heterogeneous networks and client devices (i.e. the lack of levels of details); these drawbacks seriously affect the quality of user experience.This paper presents a technical solution for streaming and visualization of compressed 3D data on the web. Our approach leans upon three strong features: (1) a dedicated progressive compression algorithm for 3D graphic data with colors producing a binary compressed format which allows a progressive decompression with several levels of details; (2) the introduction of a JavaScript halfedge data structure allowing complex geometrical and topological operations on a 3D mesh; (3) the multi-thread JavaScript / WebGL implementation of the decompression scheme allowing 3D data streaming in a web browser. Experiments and comparison with existing solutions show promising results in terms of latency, adaptability and quality of user experience. . (Hide...)

• [37] Investigating the Rate-Distortion Performance of a Wavelet-Based Mesh Compression Algorithm by Perceptual and Geometric Distortion Metrics
  Maja Krivokuća, Burkhard Wuensche, Waleed Abdulla, Guillaume Lavoué, International Conference on Computer Graphics, Visualization and Computer Vision  (WSCG), Plzen, Czech Republic, June 2012. [Paper]
• [36] SHREC'12 Track: 3D mesh segmentation
  Guillaume Lavoué, Jean-Philippe Vandeborre,  Halim Benhabiles, Mohamed Daoudi, Kai Huebner, Michela Mortara, Michela Spagnuolo, Eurographics Workshop on 3D Object Retrieval (3DOR), Cagliari, Italy, May 2012. (Abstract...) [Paper] (Copyright Eurographics)

  3D mesh segmentation is a fundamental process in many applications such as shape retrieval, compression,deformation, etc. The objective of this track is to evaluate the performance of recent segmentation methods using a ground-truth corpus and an accurate similarity metric. The ground-truth corpus is composed of 28 watertight models, grouped in five classes (animal, furniture, hand, human and bust) and each associated with 4 ground-truth segmentations done by human subjects. 3 research groups have participated to this track, the accuracy of their segmentation algorithms have been evaluated and compared with 4 other state-of-the-art methods. (Hide...)

• [35] Kinematic skeleton extraction based on motion boundaries for 3D dynamic meshes
  Halim Benhabiles, Guillaume Lavoué, Jean-Philippe Vandeborre and Mohamed Daoudi, Eurographics Workshop on 3D Object Retrieval (3DOR), Cagliari, Italy, May 2012. (Abstract...) [Paper] (Copyright Eurographics)

  This paper presents a precise kinematic skeleton extraction method for 3D dynamic meshes. Contrary to previousmethods, our method is based on the computation of motion boundaries instead of detecting object parts characterized by rigid transformations. Thanks to a learned boundary edge function, we are able to compute efficiently a set of motion boundaries which in fact correspond to all possible articulations of the 3D object. Moreover, the boundaries are detected even if the parts linked to an object’s articulation are immobile over time. The different boundaries are then used to extract the kinematic skeleton. Experiments show that our algorithm produces more precise skeletons compared to previous methods. (Hide...)

• [34]  Perceptual metrics for static and dynamic triangle meshes  
  Massimiliano Corsini, Mohamed-Chaker Larabi, Guillaume Lavoué, Oldřich Petřík, Libor Váša, Kai Wang,  State of The Art Report (STAR), Eurographics, Cagliari, Italy, May 2012. (Abstract...) (Copyright Eurographics)

  Almost all mesh processing procedures cause some more or less visible changes in the appearance of objects representedby polygonal meshes. In many cases, such as mesh watermarking, simplification or lossy compression, the objective is to make the change in appearance negligible, or as small as possible, given some other constraints. Measuring the amount of distortion requires taking into account the final purpose of the data. In many applications, the final consumer of the data is a human observer, and therefore the perceptibility of the introduced appearance change by a human observer should be the criterion that is taken into account when designing and configuring the processing algorithms. In this review, we discuss the existing comparison metrics for static and dynamic (animated) triangle meshes. We describe the concepts used in perception-oriented metrics used for 2D image comparison, and we show how these concepts are employed in existing 3D mesh metrics. We describe the character of subjective data used for evaluation of mesh metrics and provide comparison results identifying the advantages and drawbacks of each method. Finally, we also discuss employing the perception-correlated metrics in perception-oriented mesh processing algorithms. (Hide...)

• [33] MEPP - 3D Mesh Processing Platform  
  Guillaume Lavoué, Martial Tola, Florent Dupont,  International Conference on Computer Graphics Theory and Applications (GRAPP), Rome, Italy, February 2012. (Abstract...) [Paper]

  This paper presents MEPP, an open source platform for 3D mesh processing. This platform already contains alarge set of processing tools from classical ones (simplification, subdivision, segmentation) to more technical algorithms (compression, watermarking, Boolean operation, perceptual metrics, etc.). Its main objective is to allow a quick start for both users and developers by providing highly detailed tutorials and simple integration mechanisms, through a modular architecture where components are implemented as dynamic plugins. . (Hide...)

• [32] Bag of Words and Local Spectral Descriptor for 3D Partial Shape Retrieval  
  Guillaume Lavoué, Eurographics Workshop on 3D Object Retrieval (3DOR), Llandudno, UK, April 2011. (Abstract...) [Paper] (Copyright Eurographics)

  This paper presents a 3D shape retrieval algorithm based on the Bag of Words (BoW) paradigm. For a given 3D shape, the proposed approach considers a set of feature points uniformly sampled on the surface and associated with local Fourier descriptors; this descriptor is computed in the neighborhood of each feature point by projecting the geometry onto the eigenvectors of the Laplace-Beltrami operator, it is highly discriminative, robust to connectivity and geometry changes and also fast to compute. In a preliminary step, a visual dictionary is built by clustering a large set of feature descriptors, then each 3D shape is described by an histogram of occurrences of these visual words. The performances of our approach have been compared against very recent state-of-theart methods on several different datasets. For global shape retrieval our approach is comparable to these recent works, however it clearly outperforms them in the case of partial shape retrieval. (Hide...)

• [31] SHREC'11 Track: Shape retrieval on Non-Rigid 3D Watertight Meshes  
  Z. Lian, A. Godil, B. Bustos, M. Daoudi, J. Hermans, S. Kawamura, Y. Kurita, G. Lavoué, H.V. Nguyen, R. Ohbuchi, Y. Ohkita, Y. Ohishi, F. Porikli, M. Reuter, I. Sipiran, D. Smeets, P. Suetens, H. Tabia, and D. Vandermeulen, Eurographics Workshop on 3D Object Retrieval (3DOR), Llandudno, UK, April 2011.  [Paper] (Copyright Eurographics)
• [30] A subjective experiment for 3D-mesh segmentation evaluation
  Halim Benhabiles, Guillaume Lavoué, Jean-Philippe Vandeborre and Mohamed Daoudi,  IEEE International Workshop on Multimedia Signal Processing (MMSP) , St-Malo, France, October 2010. (Abstract...) [Paper] (Copyright IEEE)

  In this paper we present a subjective quality assessmentexperiment for 3D-mesh segmentation. For this end, we carefully designed a protocol with respect to several factors namely the rendering conditions, the possible interactions, the rating range, and the number of human subjects. To carry out the subjective experiment, more than 40 human observers have rated a set of 250 segmentation results issued from various algorithms. The obtained Mean Opinion Scores, which represent the human subjects’ point of view toward the quality of each segmentation, have then been used to evaluate both the quality of automatic segmentation algorithms and the quality of similarity metrics used in recent mesh segmentation benchmarking systems. (Hide...)

• [29] Recognizing and localizing individual activities through graph matching  
  Anh-Phuong Ta, Christian Wolf, Guillaume Lavoué and  Atilla Baskurt, International Conference on Advanced Video and Signal-Based Surveillance (AVSS), Boston, USA, August 2010. (Abstract...) [Paper] (Copyright IEEE) Best Paper Award for the Recognition Track

  In this paper we tackle the problem of detecting individual human actions in video sequences. While the most successful methods are based on local features, which proved that they can deal with changes in background, scale and illumination, most existing methods have two main shortcomings: first, they are mainly based on the individual power of spatio-temporal interest points (STIP), and therefore ignore the spatio-temporal relationships between them. Second, these methods mainly focus on direct classification techniques to classify the human activities, as opposed to detection and localization. In order to overcome these limitations, we propose a new approach, which is based on a graph matching algorithm for activity recognition. In contrast to most previous methods which classify entire video sequences, we design a video matching method from two sets of ST-points for human activity recognition. First, points are extracted, and a hyper graphs are constructed from them, i.e. graphs with edges involving more than 2 nodes (3 in our case). The activity recognition problem is then transformed into a problem of finding instances of model graphs in the scene graph. By matching local features instead of classifying entire sequences, our method is able to detect multiple different activities which occur simultaneously in a video sequence. Experiments on two standard datasets demonstrate that our method is comparable to the existing techniques on classification, and that it can, additionally, detect and localize activities. (Hide...)

• [28] Remote scientific visualization of progressive 3D meshes with X3D  
  Adrien Maglo, Guillaume Lavoué, Céline Hudelot, Ho Lee, Christophe Mouton, Florent Dupont, International Conference on 3D Web Technology (Web3D), Los Angeles, USA, July 2010. (Abstract...) [Paper]  (Copyright ACM)

  This paper presents a framework, integrated into the X3D format, for the streaming of 3D content in the context of remote scientific visualization; a progressive mesh com- pression method is proposed that can handle 3D objects associated with attributes like colors, while producing high quality intermediate Levels Of Detail (LOD). Efficient adap- tation mechanisms are also proposed so as to optimize the LOD management of the 3D scene according to different constraints like the network bandwidth, the device graphic capability, the display resolution and the user preferences. Experiments demonstrate the efficiency of our approach in scientific visualization scenarii. . (Hide...)

• [27] Learning an efficient and robust graph matching procedure for specific object recognition  
  Jérôme Revaud, Guillaume Lavoué, Yasuo Ariki and Atilla Baskurt, Jean-Michel Jolion, International Conference on Pattern Recognition (ICPR), Istanbul, Turkey, August 2010. (Abstract...) [Paper]  (Copyright IEEE)

  We present a fast and robust graph matching approachfor 2D specific object recognition in images. From a small number of training images, a model graph of the object to learn is automatically built. It contains its local keypoints as well as their spatial proximity relationships. Training is based on a selection of the most efficient subgraphs using the mutual information. The detection uses dynamic programming with a lattice and thus is very fast. Experiments demonstrate that the proposed method outperforms the specific object detectors of the state-of-the-art in realistic noise conditions. . (Hide...)

• [26] 3D Pairwise features for human action recognition  
  Anh-Phuong Ta, Christian Wolf, Guillaume Lavoué and  Atilla Baskurt,  International Conference on Pattern Recognition (ICPR), Istanbul, Turkey, August 2010. (Abstract...) [Paper] (Copyright IEEE)

  Existing action recognition approaches mainly relyon the discriminative power of individual local descriptors extracted from spatio-temporal interest points (STIP), while the geometric relationships among the local features1 are ignored. This paper presents new features, called pairwise features (PWF), which encode both the appearance and the spatio-temporal relations of the local features for action recognition. First STIPs are extracted, then PWFs are constructed by grouping pairs of STIPs which are both close in space and close in time. We propose a combination of two codebooks for video representation. Experiments on two standard human action datasets: the KTH dataset and the Weizmann dataset show that the proposed approach outperforms most existing methods (Hide...)

• [25] Scale-Invariant Proximity Graph for Fast Probabilistic Object Recognition  
  Jérôme Revaud, Guillaume Lavoué, Yasuo Ariki and Atilla Baskurt, ACM International Conference on Image and Video Retrieval (CIVR), Xi'an, China, July 2010.(Abstract...) [Paper] (Copyright ACM)

  A pseudo-hierarchical graph matching procedure dedicatedto object recognition is presented in this paper. From a single model image, a graph is built by extracting invariant local features and linking them according to a so-called proximity rule. The resulting graph presents several interesting properties including invariance to scale, robustness to various distortions and empirical linearity of the number of edges with respect to the number of nodes. The matching process is made hierarchical in order to increase both speed and detection performances. It relies on progressively incorporating the smaller model features as the hierarchy level increases. As a result, even a matching between graphs containing thousands of nodes is very fast (a few milliseconds). Experiments demonstrates that the method outperforms state-of-the-art specific object detectors in terms of precision-recall measures and detection time. . (Hide...)

• [24] A Benchmark for 3D Mesh Watermarking  
  Kai Wang, Guillaume Lavoué, Florence Denis,  Atilla Baskurt and Xiyan He, IEEE Shape Modeling International (SMI) , Avignon, France, June 2010. (Abstract...) [Paper] (Copyright IEEE)

  Abstract—This paper presents a benchmarkingsystem for the evaluation of robust mesh watermarking methods. The proposed benchmark has three different components: a “standard” mesh model collection, a software tool and two application-oriented evaluation protocols. The software tool integrates both geometric and perceptual measurements of the distortion induced by watermark embedding, and also the implementation of a variety of attacks on watermarked meshes. The two evaluation protocols define the main steps to follow when conducting the evaluation experiments. The efficiency of the benchmark is demonstrated through the evaluation and comparison of two recent robust algorithms. (Hide...)

• [23] A Framework for Data-Driven Progressive Mesh Compression  
  Gabriel Cirio, Guillaume Lavoué and Florent Dupont,  International Conference on Computer Graphics Theory and Applications (GRAPP),  Anger, France, May 2010. (Abstract...) [Paper]

  Progressive mesh compression techniques have reached very high compression ratios. However, these techniquesusually do not take into account associated properties of meshes such as colors or normals, no matter their size, nor do they try to improve the quality of the intermediate decompression meshes. In this work, we propose a framework that uses the associated properties of the mesh to drive the compression process, resulting in an improved quality of the intermediate decompression meshes. Based on a kd-tree geometry compression algorithm, the framework is generic enough to allow any property or set of properties to drive the compression process provided the user defines a distance function for each property. The algorithm builds the kd-tree structure using a voxelisation process, which recursively separates the set of vertices according to the associated properties distances. We evaluate our method by comparing its compression ratios to recent algorithms. In order to evaluate the visual quality of the intermediate meshes, we carried a perceptive evaluation with human subjects. Results show that at equal rates, our method delivers an overall better visual quality. The algorithm is particularly well suited for the compression of meshes where geometry and topology play a secondary role compared to associated properties, such as with many scientific visualization models. (Hide...)

• [22] New methods for progressive compression of colored 3D Mesh  
  Ho Lee, Guillaume Lavoué and Florent Dupont,  International Conference on Computer Graphics, Visualization and Computer Vision (WSCG), Plzen, Czech Republic, February 2010. (Abstract...) [Paper]

  In this paper, we present two methods to compress colored 3D triangular meshes in a progressive way. Although many progressive algorithms exist for efficient encoding of connectivity and geometry, none of these techniques consider the color data in spite of its considerable size. Based on the powerful progressive algorithm from Alliez and Desbrun [All01a], we propose two extensions for progressive encoding and reconstruction of vertex colors: a prediction-based method and a mapping table method. In the first one, after transforming the initial RGB space into the Lab space, each vertex color is predicted by a specific scheme using information of its neighboring vertices. The second method considers a mapping table with reduced number of possible colors in order to improve the rate-distortion tradeoff. Results show that the prediction method produces quite good results even in low resolutions, while the mapping table method delivers similar visual results but with a fewer amount of bits transmitted depending on the color complexity of the model. (Hide...)

• [21] Adaptive coarse-to-fine quantization for optimizing rate-distortion of progressive mesh compression  
  Ho Lee, Guillaume Lavoué and Florent Dupont,  Vision, Modeling, and Visualization Workshop (VMV), Braunschweig, Germany, November 2009. (Abstract...) [Paper]

  We propose a new connectivity-based progressive compression approach for triangle meshes. The key idea is to adapt the quantization precision to the resolution of each intermediate mesh so as to optimize the rate-distortion trade-off. This adaptation is automatically determined during the encoding process and the overhead is efficiently encoded using geometrical prediction techniques. We also introduce an optimization of the geometry coding by using a bijective discrete rotation. Results show that our approach delivers a better rate-distortion behavior than both connectivity-based and geometry-based compression state of the art methods. (Hide...)

• [20]  Global triangular mesh regularization using conditional Markov random fields
  Vincent Vidal, Christian Wolf, Florent Dupont, Guillaume Lavoué, Symposium on Geometry Processing (SGP), Poster, Berlin, Germany, July 2009. [Poster] 
• [19] Local patch blind spectral watermarking method for 3D graphics  
  Ming Luo, Kai Wang, Adrian G. Bors and  Guillaume Lavoué,  International Workshop on Digital Watermarking (IWDW), Lecture Notes on Computer Science, Guildford, UK, August 2009. (Abstract...) [Paper] (Copyright Springer)

  In this paper, we propose a blind watermarking algorithm for 3D meshes. The proposed algorithm embeds spectral domain constraints in segmented patches. After aligning the 3D object using volumetric moments , the patches are extracted using a robust segmentation method which ensures that they have equal areas. One bit is then embedded in each patch by enforcing specific constraints in the distribution of its spectral coefficients by using Principal Component Analysis (PCA). A series of experiments and comparisons with state-of-the-art in 3D graphics wa- termarking have been performed; they show that the proposed scheme provides a very good robustness against both geometry and connectivity attacks, while introducing a low level of dis torsion. (Hide...)

• [18] 3D Object detection and viewpoint selection in sketch images using local patch-based Zernike moments  
  Anh-Phuong Ta, Christian Wolf, Guillaume Lavoué and  Atilla Baskurt,  IEEE Workshop on Content Based Multimedia Indexing (CBMI), Crete, Greece, June 2009. (Abstract...) [Paper] (Copyright IEEE)

  In this paper we present a new approach to detect and recognize 3D models in 2D storyboards which have been drawn during the production process of animated cartoons. Our method is robust to occlusion, scale and rotation. The lack of texture and color makes it difficult to extract local features of the target object from the sketched storyboard. Therefore the existing approaches using local descriptors like interest points can fail in such images. We propose a new framework which combines patch-based Zernike descriptors with a method enforcing spatial constraints for exactly detecting 3D models represented as a set of 2D views in the storyboards. Experimental results show that the proposed method can deal with partial object occlusion and is suitable for poorly textured objects. (Hide...)

• [17] A framework for the objective evaluation of segmentation algorithms using a ground-truth of human segmented 3D-models
  Halim Benhabiles, Jean-Philippe Vandeborre, Guillaume Lavoué and Mohamed Daoudi,  IEEE Shape Modeling International (SMI), Beijing, China, June  2009. (Abstract...) [Paper] (Copyright IEEE)

  In this paper, we present an evaluation method of 3D-mesh segmentation algorithms based on a ground-truth corpus. This corpus is composed of a set of 3D-models grouped in different classes (animals, furnitures, etc.) associated with several manual segmentations produced by human observers. We define a measure that quantifies the consistency between two segmentations of a 3D-model, whatever their granularity. Finally, we propose an objective quality score for the automatic evaluation of 3D-mesh segmentation algorithms based on these measures and on the ground-truth corpus. Thus the quality of segmentations obtained by automatic algorithms is evaluated in a quantitative way thanks to the quality score, and on an objective basis thanks to the ground-truth corpus. Our approach is illustrated through the evaluation of two recent 3D-mesh segmentation methods. (Hide...)

• [16] Markov Random Fields for Improving 3D Mesh Analysis and Segmentation  
  Guillaume Lavoué and Christian Wolf, Eurographics 2008 Workshop on 3D Object Retrieval, pp. 25-32, Crete, Greece, April 2008. (Abstract...) [exe] [Paper] (Copyright Eurographics)

  Mesh analysis and clustering have became important issues in order to improve the efficiency of common processingoperations like compression, watermarking or simplification. In this context we present a new method for clustering / labeling a 3D mesh given any field of scalar values associated with its vertices (curvature, density, roughness etc.). Our algorithm is based on Markov Random Fields, graphical probabilistic models. This Bayesian framework allows (1) to integrate both the attributes and the geometry in the clustering, and (2) to obtain an optimal global solution using only local interactions, due to the Markov property of the random field. We have defined new observation and prior models for 3D meshes, adapted from image processing which achieve very good results in terms of spatial coherency of the labeling. All model parameters are estimated, resulting in a fully automatic process (the only required parameter is the number of clusters) which works in reasonable time (several seconds). (Hide...)

• [15] A Fragile Watermarking Scheme for Authentication of Semi-regular Meshes  
  Kai Wang, Guillaume Lavoué, Florence Denis and Atilla Baskurt, Eurographics 2008, Short Paper, pp. 5-8, Crete, Greece, April 2008. (Abstract...) [Paper] (Copyright Eurographics)

  This paper presents a fragile watermarking scheme for authentication of 3D semi-regular meshes. After onewavelet decomposition, the watermark is inserted by slightly modifying the norms and orientations of the obtained wavelet coefficient vectors. The inserted watermark is robust to the so-called content-preserving attacks including vertex reordering and similarity transformations. However, it is vulnerable to others attacks such as local and global geometric modifications and remeshing since the objective is to check the integrity of the mesh. Additionally, according to the watermark extraction result, these attacks can be precisely located on the surface of the attacked mesh in a blind way. Sufficient security level is also achieved by introducing secret keys and by using scalar Costa quantization scheme with appropriate parameter values. Experimental results demonstrate the efficacy of the proposed watermarking scheme. (Hide...)

• [14] Feature-Based Subdivision Surface Fitting  
  Guillaume Lavoué and Florent Dupont, ACM SIGGRAPH 2007, Poster, San Diego, California, USA, August 2007. [Abstract paper] (Copyright ACM)
• [13] A Roughness Measure for 3D Mesh Visual Masking  
  Guillaume Lavoué, ACM SIGGRAPH Symposium on Applied Perception in Graphics and Visualization (APVG), pp. 57-60, Tübingen, Germany, July 2007.(Abstract...) [exe] [Paper] (Copyright ACM)

  3D models are subject to a wide variety of processing operations such as compression, simplification or watermarking, which introduce slight geometric modifications on the shape. The main issue is to maximize the compression/simplification ratio or the watermark strength while minimizing these visual degradations. However few algorithms exploit the human visual system to \textit{hide} these degradations, while perceptual attributes could be quite relevant for this task. Particularly, the Masking Effect defines the fact that a signal can be masked by the presence of another signal with similar frequency or orientation. In this context we introduce the notion of \textit{roughness} for a 3D mesh, as a local measure of geometric noise on the surface. Indeed, a textured (or \textit{rough}) region is able to hide geometric distortions much better than a smooth one. Our measure is based on curvature analysis on local windows of the mesh and is independent of the resolution/connectivity of the object. An application to Visual Masking is presented and discussed. (Hide...)

• [12] Fast and cheap object recognition by linear combination of views  
  Jérôme Revaud, Guillaume Lavoué, Yasuo Ariki and Atilla Baskurt, ACM International Conference on Image and Video Retrieval (CIVR), pp. 194-201, Amsterdam, The Netherlands, July 2007.(Abstract...) [Paper] (Copyright ACM)

  In this paper, we present a real-time algorithm for 3D object detection in images. Our method relies on the Ullman and Basri theory which claims that the same object under different transformations can often be expressed as the linear combinations of a small number of its views. Thus, in our framework the 3D object is modelized by two 2D images associated with spatial relationships described by localinvariant feature points. The recognition is based on feature points detection and alignment with the model. Important theoretical optimizations have been introduced in order to speed up the original full alignment scheme and to reduce the model size in memory. The recognition process is based on a very fast recognition loop which quickly eliminates outliers. The proposed approach does not require a segmentation stage, and it is applicable to cluttered scenes. The small size of the model and the rapidity of the detection make this algorithm articularly suitable for real-time applications on mobile devices. (Hide...)

• [11] Hierarchical Blind Watermarking of 3D Triangular Meshes  
  Kai Wang, Guillaume Lavoué, Florence Denis and Atilla Baskurt, IEEE International Conference on Multimedia & Expo (ICME), pp. 1235-1238, Beijing, China, July 2007. (Abstract...) [Preprint] (Copyright IEEE)

  An original hierarchical watermarking scheme is proposed in this paper. A geometrically robust watermark and a high-capacity watermark are inserted in different resolution levels of the wavelet decomposition of a semi-regular mesh by modifying the norms of wavelet coefficients. Both watermarks are blind and invariant to similarity transformations. The robustness of the first watermark is achieved by synchronizing and quantizing watermark primitives according to edges lengths of the coarsest level, which are quite insensible to geometrical attacks. The high capacity of the second watermark is obtained by considering the permutation of the norms of a group of wavelet coefficients. Experiments have proven the high robustness of the first watermark under common geometrical attacks. To our knowledge, the capacity of the second method, which can attain the factorial of the candidate coefficients number, is the highest for 3D meshes in the literature. (Hide...)

• [10] Three-Dimensional Meshes Watermarking: Review and Attack-Centric Investigation  
  Kai Wang, Guillaume Lavoué, Florence Denis and Atilla Baskurt, Information Hiding (IH), Lecture Notes on Computer Science, Vol. 4567, pp. 50-64, Saint Malo, France, June 2007. (Abstract...) [Preprint] (Copyright Springer)

  The recent decade has seen the emergence of 3D meshes in industrial, medical and entertainment applications. Therefore, their intellectual property protection problem has attracted more and more attention in both the research and industrial realms. This paper gives a synthetic review of 3D mesh watermarking techniques, which are deemed to be a potential effective solution to the above problem. We begin with a discussion on the particular difficulties encountered in applying watermarking on 3D meshes. Then some typical algorithms are presented and analyzed, classifying them in two categories: spatial and spectral. Considering the important impact of the different attacks on the design of 3D mesh watermarking algorithms, we provide an attack-centric viewpoint of this state of the art. Finally, some special issues and possible future working directions are discussed. (Hide...)

• [9] A Watermarking Framework for Subdivision Surfaces 
  Guillaume Lavoué, Florence Denis, Florent Dupont and Atilla Baskurt, International Workshop on Multimedia Content Representation, Classification and Security (IWMRCS), Lecture Notes on Computer Science, Vol. 4105, pp. 223-231, Istanbul, Turkey, September 2006. (Abstract...) [Paper] (Copyright Springer)

  This paper presents a robust watermarking scheme for 3D subdivision surfaces. Our proposal is based on a frequency domain decomposition of the subdivision control mesh and on spectral coefficients modulation. The compactness of the cover object (the coarse control mesh) has led us to optimize the trade-off between watermarking redundancy (which insures robustness) and imperceptibility by introducing two contributions: (1) Spectral coefficients are perturbed according to a new modulation scheme analyzing the spectrum shape and (2) the redundancy is optimized by using error correcting codes. Since the watermarked surface can be attacked in a subdivided version, we have introduced a so-called synchronization algorithm to retrieve the control polyhedron, starting from a subdivided, attacked version. Through the experiments, we have demonstrated the high robustness of our scheme against both geometry and connectivity alterations. (Hide...)

• [8] Perceptually driven 3D distance metrics with application to watermarking 
  Guillaume Lavoué, Elisa Drelie Gelasca, Florent Dupont, Atilla Baskurt and Touradj Ebrahimi, SPIE Applications of Digital Image Processing XXIX, San Diego, August 2006. (Abstract...)  [exe] [Paper] (Copyright SPIE)

  This paper presents an objective structural distorsion measure which reflects the visual similarity between 3D meshes and thus can be used for quality assessment. The proposed tool is not linked to any specific application and thus can be used to evaluate any kinds of 3D mesh processing algorithms (simplification, compression, watermarking etc.). This measure follows the concept of structural similarity recently introduced for 2D image quality assessment by Wang \emph{et al.} \cite{WANG:2004} and is based on curvature analysis (mean, standard deviation, covariance) on local windows of the meshes. Evaluation and comparison with geometric metrics are done through a subjective experiment based on human evaluation of a set of distorted objects. A quantitative perceptual metric is also derived from the proposed structural distorsion measure, for the specific case of watermarking quality assessment, and is compared with recent state of the art algorithms. Both visual and quantitative results demonstrate the robustness of our approach and its strong correlation with subjective ratings. (Hide...)

• [7] Digital Watermarking of Compressed 3D Meshes
  Florence Denis, Guillaume Lavoué, Florent Dupont and Atilla Baskurt, International Conference on Machine Intelligence (ACIDCA-ICMI’2005), Tozeur, Tunisia, November, 2005. (Abstract...) [Paper]

  This paper presents a robust watermarking algorithm applied to 3D compressed polygonal meshes. Copyright protection of 3D models becomes very important for many applications using public networks. As some recent compression techniques allow very high compression rates, it is of interest to verify that watermarking techniques support this kind of attack. In this paper we present the complete scheme developed: the compression algorithm, the watermarking algorithm and the mark extraction process. (Hide...)

• [6] High rate compression of 3D meshes using a subdivision scheme
  Guillaume Lavoué, Florent Dupont and Atilla Baskurt, European Signal Processing Conference (EUSIPCO’2005), Antalya, Turkey, September, 2005. [Paper]
• [5] Subdivision surface fitting for efficient compression and coding of 3D models
  Guillaume Lavoué, Florent Dupont and Atilla Baskurt, SPIE Visual Communications and Image Processing (VCIP'2005), Vol. 5960, pp. 1159-1170, Beijing, China, July, 2005. (Abstract...) [Paper] (Copyright SPIE)

  In this paper we present a new framework, based on subdivision surface fitting, for high rate compression and coding of 3D models. Our algorithm fits the input 3D model, represented by a polygonal mesh, with a piecewise smooth subdivision surface represented by a coarse control polyhedron. Our fitting scheme, particularly suited for meshes issued from mechanical or CAD parts, aims at getting close to the optimality in terms of control points number, while remaining independent of the connectivity of the input mesh. The found subdivision control polyhedron is much more compact than the original mesh and visually represents the same shape after several subdivision steps, without artifacts or cracks, like traditional lossy compression schemes. This control polyhedron is then encoded specifically to give the final compressed stream. Experiments conducted on several 3D models have proven the coherency and the efficiency of our framework, compared with existing compression methods.(Hide...)

• [4] Toward a near optimal quad/triangle subdivision surface fitting
  Guillaume Lavoué, Florent Dupont andAtilla Baskurt, IEEE Int. Conf. on 3-D Digital Imaging and Modeling (3DIM'2005), pp. 402-409, Ottawa, Canada, June 2005. (Abstract...) [Paper] (Copyright IEEE Computer Society)

  In this paper we present a new framework for subdivision surface fitting of arbitrary surfaces (not closed objects) represented by polygonal meshes. Our approach is particularly suited for output surfaces from a mechanical or CAD object segmentation for a piecewise subdivision surface approximation. Our algorithm produces a mixed quadrangle-triangle control mesh, near optimal in terms of face and vertex numbers while remaining independent of the connectivity of the input mesh. The first step approximates the boundaries with subdivision curves and creates an initial subdivision surface by optimally linking the boundary control points with respect to the lines of curvature of the target surface. Then, a second step optimizes the initial control polyhedron by iteratively moving control points and enriching regions according to the error distribution. Experiments conducted on several surfaces and on a whole segmented mechanical object, have proven the coherency and the efficiency of our algorithm, compared with existing methods.(Hide...)

• [3] Curvature tensor Based Triangle Mesh Segmentation with Boundary Rectification
  Guillaume Lavoué, Florent Dupont and Atilla Baskurt, IEEE Computer Graphics International (CGI'2004), pp. 10-17, Crete, Greece, June 2004. (Abstract...) [Paper] (Copyright IEEE Computer Society)

  This paper presents a new and efficient algorithm for the decomposition of 3D arbitrary triangle meshes into surface patches. The algorithm is based on the curvature tensor field analysis and presents two distinct complementary steps: a region based segmentation, which is an improvement of that presented in Lavoue et al. [Lavoue G, Dupont F, Baskurt A. Constant curvature region decomposition of 3D-meshes by a mixed approach vertex-triangle, J WSCG 2004;12(2):245–52] and which decomposes the object into known and near constant curvature patches, and a boundary rectification based on curvature tensor directions, which corrects boundaries by suppressing their artifacts or discontinuities. Experiments were conducted on various models including both CAD and natural objects, results are satisfactory. Resulting segmented patches, by virtue of their properties (known curvature, clean boundaries) are particularly adapted to computer graphics tasks like parametric or subdivision surface fitting in an adaptive compression objective. (Hide...)

• [2] Constant Curvature Region Decomposition of 3D-Meshes by a Mixed Approach Vertex-Triangle
  Guillaume Lavoué, Florent Dupont and Atilla Baskurt, Journal of WSCG (WSCG’2004), Vol.12, No.2, pp. 245-252, ISSN 1213-6972, February 2-6, 2004, Plzen, Czech Republic. (Abstract...) [Paper]

  We present a new and efficient algorithm for decomposition of arbitrary triangle meshes into connected subsets of meshes called regions. Our method, based on discrete curvature analysis decomposes the object into almost constant curvature surfaces and not only “cut” the object along its hard edges like traditional methods. This algorithm is an hybrid approach vertex-triangle, it is based on three major steps: vertices are first classified using their discrete curvature values, then connected triangle regions are extracted via a region growing process and finally similar regions are merged using a region adjacency graph in order to obtain final patches. Experiments were conducted on both CAD and natural models, results are satisfactory. Segmented patches can then be used instead of the complete complex model to facilitate computer graphic tasks such as smoothing, surface fitting or compression. (Hide...)

• [1] Système de Recherche d'Images et de Navigation Visuelle Basé sur une Approche Locale
  Khalid Idrissi, Guillaume Lavoué, Julien Ricard, Int. Conf. on Image and Signal Processing (ICISP'2003), pp. 119-128, Agadir, Maroc, June 2003.

Habilitation

• Lavoué, G.,  Compression, tatouage et reconnaissance d'objets 3D, Apports de la perception, Habilitation soutenue le 4 Avril 2013 à L'INSA de Lyon. Manuscrit (PDF)
  

PhD Thesis

• Lavoué, G.,  Compression de surfaces, basée sur la subdivision inverse, pour la transmission bas débit et la visualisation progressive, Thèse soutenue le 1er Décembre 2005, à l'université Claude Bernard, Lyon 1. Manuscrit (PDF)