TITANE Inria project-team https://team.inria.fr/titane Geometric Modeling of 3D Environments Wed, 31 Jan 2024 14:18:32 +0000 en-US hourly 1 https://wordpress.org/?v=5.9.7 PhD position on Object Vectorization (PEPR IRIMA project) https://team.inria.fr/titane/phd-position-on-object-vectorization/ Wed, 31 Jan 2024 14:15:36 +0000 https://team.inria.fr/titane/?p=2228 Continue reading

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We propose a PhD position on Object Vectorization from images and 3D data measurements. More info can be found here

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Postdoctoral position: Valid large-scale mesh generation (PEPR NUMPEX project) https://team.inria.fr/titane/postdoctoral-position-valid-large-scale-mesh-generation-pepr-numpex-project/ Fri, 19 Jan 2024 13:32:12 +0000 https://team.inria.fr/titane/?p=2203 Continue reading

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Download offer

 

 

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Master internship on massive point cloud processing https://team.inria.fr/titane/master-internship-on-massive-point-cloud-processing/ Wed, 29 Nov 2023 08:49:54 +0000 https://team.inria.fr/titane/?p=2189 Continue reading

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More info can be found here

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Master internship on reconstruction of the Cosmic Web skeleton https://team.inria.fr/titane/master-internship-on-reconstruction-of-the-cosmic-web-skeleton/ Tue, 07 Nov 2023 08:06:12 +0000 https://team.inria.fr/titane/?p=2182 Continue reading

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For Master1 or Master2 students in Computer Science or Mathematics. In collaboration with the Observatoire de la Côte d’Azur.

More info available here

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Pierre Alliez https://team.inria.fr/titane/pierre-alliez/ Fri, 30 Sep 2022 09:10:00 +0000 https://team.inria.fr/titane/?p=135 Continue reading

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Inria Senior Researcher
Team Leader
President of the Inria Evaluation Commission
Scientific coordinator of the Inria-DFKI partnership
3IA Côte d’Azur Chair
Project-team TITANE
Inria Sophia Antipolis – Méditerranée

Contact information
Pierre Alliez
Inria Sophia-Antipolis
2004 route des Lucioles BP 93
06902 Sophia-Antipolis cedex
FRANCE
Office: Y313 (Byron building)
Phone: (33) 4 92 38 76 77
Email: pierre.alliez (replace by arobas) inria.fr

My main research interests are on topics commonly referred to as Geometry Processing: geometry compression, surface approximation, mesh parameterization, surface remeshing, mesh generation and surface reconstruction. Initially considered as a subfield of Computer Graphics and Computational Geometry, Geometry Processing has developed over the last years into a whole research community seeking automatic, computerized processing of complex shapes.

I was program co-chair of the EUROGRAPHICS Symposium on Geometry Processing 2008, Pacific Graphics 2010, Geometric Modeling and Processing 2014, EUROGRAPHICS 2019 and Solid and Physical Modeling 2019.

I am the co-Editor in Chief of the Computer Graphics Forum since 2022.
Associate editor of the ACM Transactions on Graphics between 2010 and 2017, of Computer Graphics Forum between 2018 and 2021, and of Computer Aided Design between 2019 and 2021. I have been awarded in 2011 a Starting Grant from the ERC (European Research Council), entitled “IRON”, which stands for “Robust Geometry Processing”. I have been awarded in 2017 an ERC proof of concept grant, entitled “TITANIUM” (software components for robust geometry processing). I received the Eurographics Young Researcher Award in 2005.

Publications
See google scholar
– See list of publications on HAL
– See publications on dlbp
– Publications on TITANE web site

Recent (not too old) publications:

Feature-Preserving Offset Mesh Generation from Topology-Adapted Octrees
Daniel Zint, Nissim Maruani, Mael Rouxel-Labbé, Pierre Alliez
Computer Graphics Forum, 2023, Proceedings of Eurographics Symposium on Geometry Processing 2023.

Variational Shape Reconstruction via Quadric Error Metrics
Tong Zhao, Laurent Busé, David Cohen-Steiner, Tamy Boubekeur, Jean-Marc Thiery, Pierre Alliez
ACM Transactions on Graphics 2023, to appear at ACM SIGGRAPH 2023.
Project page
Alpha Wrapping with an Offset
Cédric Portaneri, Mael Rouxel-Labbé, Michael Hemmer, David Cohen-Steiner, Pierre Alliez.
ACM Transactions on Graphics 2022, to appear at ACM SIGGRAPH 2022.
See CGAL Package.
See youtube video (15 minutes)
Simplification of 2D Polygonal Partitions via Point-line Projective Duality, and Application to Urban Reconstruction
Julien Vuillamy, André Lieutier, Florent Lafarge, Pierre Alliez
Computer Graphics Forum, 2022.
Progressive Discrete Domains for Implicit Surface Reconstruction
Tong Zhao, Pierre Alliez, Tamy Boubekeur, Laurent Busé, Jean-Marc Thiery
Computer Graphics Forum, Wiley, In press, Proceedings of the EUROGRAPHICS Symposium on Geometry Processing 2021
Delaunay Meshing and Repairing of NURBS Models
Xiao Xiao, Pierre Alliez, Laurent Busé, Laurent Rineau
Computer Graphics Forum, Wiley, In press, Proceedings of the EUROGRAPHICS Symposium on Geometry Processing 2021
StandardGAN: Multi-source Domain Adaptation for Semantic Segmentation of Very High Resolution Satellite Images by Data Standardization.
Onur Tasar, Yuliya Tarabalka, Alain Giros, Pierre Alliez, Sebastien Clerc.
IEEE/CVF Conference on Computer Vision and Pattern Recognition EarthVision Workshop (CVPRW) Seattle, USA, 2020. Best paper award.
Cost-driven framework for progressive compression of textured meshes. Cédric Portaneri, Pierre Alliez, Michael Hemmer, Lukas Birklein, Elmar Schoemer. 10th ACM Multimedia Systems Conference, 2019. Best paper award.
Selective Padding for Polycube-Based Hexahedral Meshing. G. Cherchi, Pierre Alliez, R. Scateni, M. Lyon, D. Bommes.  Computer Graphics Forum, Wiley, 2019.
Curved Optimal Delaunay Triangulation
Leman Feng, Pierre Alliez, Laurent Busé, Hervé Delingette, and Mathieu Desbrun.ACM Transactions on Graphics (SIGGRAPH), 37(4), Art. 61, 2018.
Variance-Minimizing Transport Plans for Inter-surface Mapping

Manish Mandad, David Cohen-Steiner, Leif Kobbelt, Pierre Alliez and Mathieu Desbrun.

ACM Transactions on Graphics (SIGGRAPH), 2017.

See also Supplemental Material.

Abstract: We introduce an efficient computational method for generating dense and low distortion maps between two arbitrary surfaces of same genus. Instead of relying on semantic correspondences or surface parameterization, we directly optimize a variance-minimizing transport plan between two input surfaces that defines an as-conformal-as-possible inter-surface map satisfying a user-prescribed bound on area distortion. The transport plan is computed via two alternating convex optimizations, and is shown to minimize a generalized Dirichlet energy of both the map and its inverse. Computational efficiency is achieved through a coarse-to-fine approach in diffusion geometry, with Sinkhorn iterations modified to enforce bounded area distortion. The resulting inter-surface mapping algorithm applies to arbitrary shapes robustly, with little to no user interaction.


Students / post-docs / engineers
– 2023: Moussa Bendjilali (Cifre PhD student, AlteIA)
– 2023: Armand Zampieri (Cifre PhD student, Samp AI)
– 2023: Rahima Djahel (Postdoc, EU project BIM2TWIN)
– 2023: Abir Affane (Postdoc, collaboration with AI Verse)
– 2023: Kushagra Gupta (intern from India)
– 2023: Gauthier Drumel (intern from Polytech Sophia Antipolis)
– 2022: Nissim Maruani (PhD student, école Polytechnique)
– 2022: Theo Aguilar (intern, Polytech Nice)
– 2022: Rudransh Agrawal (intern, IIT Kharagpur )
– 2022: Amaury Autric (Ecole Polytechnique)
– 2022: Jacopo Iollo (PhD student, Inria défi ROAD-AI)
– 2022: Daniel Zint (Postdoc, jointly with Geometry Factory)
– 2021: Kacper Pluta (Postdoc, EU project BIM2TWIN)
– 2021: Nissim Maruani (intern, école Polytechnique)
– 2021: Rao Fu (PhD student, GRAPES EU project)
– 2020: Paul-Vinh Lê (intern, Ecole des Ponts ParisTech)
– 2020: Lucas Dubouchet (geometry compression)
– 2019: Tong Zhao (PhD student, 3IA Côte d’Azur)
– 2018: Julien Vuillamy (PhD student, Dassault Systèmes)
– 2018: Vasudha Varadarajan (intern from India, on binary reconstruction)
– 2018: Tong Zhao (intern from Ecole des Ponts, on geometric descriptors and spectral reconstruction)
– 2018: Vincent Vadez (Cifre PhD student on simplification of satellites, with Dorea Technology)
– 2018: Flora Quilichini (PhD student on mesh compression)
– 2018: Fernando Ireta (post-doc on indoor localization and reconstruction)
– 2017: Onur Tasar (PhD student on semantic classification of satellite images)
– 2017: Leman Feng (intern from Ecole des Ponts on Higher order meshes)
– 2017: Vinay Datta Renigunta (Efficient solver for optimal transportation)
– 2017: Dmitry Anisimov (LOD reconstruction of urban scenes)
– 2017: Cédric Portaneri (Geometry compression)
– 2016: Come Le Breton (Mesh generation)
– 2015: Guillaume Matheron (intern from ENS Paris on optimal transportation)
– 2015: Maxim Torgonskiy (Mesh generation)
– 2015: Aditya Kusupati (IIT Bombay on anisotropic metrics)
– 2015; Mohammad Rouhani (post-doc on semantic classification)
– 2015: Emmanuel Maggiori (PhD student on classification of satellite images)
– 2015: Nicolas Douillet (culture 3D clouds)
– 2014: Jinjing Shen (visiting PhD student on isotropic meshing of NURBS surfaces)
– 2014: Devdeep Ray (intern on optimal transportation)
– 2014: Henrik Zimmer (post-doc)
– 2013: Renata Rego (post-doc on Robust feature extraction)
– 2013: Anmol Garg (Intern on Shape approximation)
– 2012: Kaimo Hu (post-doc on Robust surface remeshing)
– 2012: Thijs van Lankveld (Surface reconstruction for cultural heritage data)
– 2012: Clément Jamin (Parallel algorithms and shape detection)
– 2012: Yiyi Wei (Well-centered triangulations, co-advised with Mariette Yvinec)
– 2012: Manish Mandad (PhD on robust shape approximation with guarantees)
– 2012: Sven Oesau (Indoor scene reconstruction, co-advised with Florent Lafarge)
– 2012: David Bommes (Surface tiling)
– 2011: Xavier Rolland-Neviere (Watermarking of surface meshes, at Technicolor, co-advised with Gwenael Doerr)
– 2011: Simon Giraudot (Robust reconstruction of surfaces)
– 2011: Paul Seron (Reconstruction of urban scenes)
– 2011: Renata Nascimento (visiting PhD student on quadrangle surface tiling)
– 2011: Julie Digne (post-doc on robust shape reconstruction, now researcher at CNRS in Lyon)
– 2011: Sagar Chordia (shape approximation)
– 2010: Alain Tayeb (Meshing NURBS surfaces)
– 2010: Boris Dalstein (quadrangle surface tiling)
– 2009-present: Bertrand Pellenard (PhD on surface and domain tiling, defended Dec 18th 2012)
– 2009: Hugo Feree (ENS Lyon: probing implicit surfaces, now PhD student at Inria Nancy)
– 2009: Rahul Srinivasan (IIT Bombay: accelerating ODT mesh optimization and sliver removal)
– 2008: Amit Gupta (IIT Bombay: Poisson reconstruction for polygon soups)
– 2008: Saurabh Chakradeo (IIT Bombay: Fast intersections and projections for polyhedral surfaces)
– 2007: Ankit Gupta (IIT Bombay: PCA in CGAL and application to normal estimation), now at Stanford
– 2006-2009: Jane Tournois (PhD on mesh optimization), now at Geometry Factory.
– 2006: Lakulish Antani (IIT Bombay: mesh sizing using additively weighted Voronoi diagrams), now at UNC
– 2004: Abdelkrim Mebarki (master: placement of streamlines)
– 2004: Jérôme Gahide (progressive triangle mesh compression)
– 2003-2007: Marie Samozino (Ph.D.: reconstruction of surfaces from noisy point sets, co-advised with Mariette Yvinec), now Professor in Mathematics
– 2002: Mathieu Monnier (compression of 2D vectorial data)


Software

I am an avid user of the CGAL library. I am a CGAL editor and developer as well, implementing or participating to various projects: placement of streamlines from 2D vector fields, planar parameterization of triangle surface meshes, Principal Component Analysis, Surface reconstruction, Point Set Processing and 3D Isotropic Tetrahedron Mesh Generation and Optimization.

Current Projects
– EU ITN GRAPES (Learning, processing and optimising shapes)
– EU BIM2TWIN (digital twin for construction)

Past Projects
– ANR Pisco (geometry compression)
– ANR Loca-3D (indoor localization and mapping)
– Google X (geometry processing)
– ERC Proof of Concept TITANIUM
– Google Chrome University research program
EU ERC Starting grant IRON (Robust Geometry Processing)
Grand emprunt Investissements d’avenir: Culture 3D clouds
ANR GIGA
(national project about geometric inference and analysis)
ANR GYROVIZ (national project for reconstructing urban scenes from localized photos and videos)
Focus K3D (EU FP7 Coordination Action)
AIM@SHAPE (EU Network of Excellence)
Activities

2023
– Advisory committee: EUROGRAPHICS annual conference
– Editor in chief, Computer Graphics Forum
– Programme committee: EUROGRAPHICS Symposium on Geometry Processing
– Thesis reviewer: Raphael Sulzer
– Thesis reviewer: Theo Deprelle
– Thesis reviewer: Claudio Mancinelli (University of Genova)
– Thesis committee: Florent Jousse (Inria and Université Côte d’Azur)
– Thesis commitee: Gaétan Bahl (Inria)
– HDR reviewer: Loic Landrieu (IGN)

2021
– Chair, EUROGRAPHICS PhD award committee
– Programme committee: EUROGRAPHICS Symposium on Geometry Processing
– Thesis reviewer: Pierre-Alain Langlois (Ecole des Ponts ParisTech)
– Thesis reviewer: Raphaël Groscot (Ceremade, Dauphine)
– Thesis committee: Yana Nehmé (INSA Lyon)

2020
– Advisory committee: EUROGRAPHICS annual conference
– EUROGRAPHICS PhD award committee
– SGP 2020 Software and Dataset Awards Committee
– Thesis reviewer: Adrien Poulenard (Ecole Polytechnique)
– Thesis reviewer: Shayan Nikoohemat (University Twente)
– Thesis commitee: Jean Feydy (ENS Cachan)
– Thesis committee: Simon Rodgriguez (Inria)

2019
– Full paper co-chair, EUROGRAPHICS conference.
Program co-chair, SPM conference.
– HDR reviewer: Sébastien Valette (INSA Lyon)
– Thesis committee: Jean-Philippe Bauchet (Inria)
– Thesis committee: Siargey Kachanovich (Inria)

2018
– joined editorial board of Computer Graphics Forum for three years.
– programme committee: EUROGRAPHICS Symposium on Geometry Processing
– programme committee: International Conference on Geometric Modeling and Processing (GMP)
– programme committee: Shape Modeling International
– advisory committee: EUROGRAPHICS annual conference
– HDR committee: Stefanie Wuhrer (Inria Grenoble)
– Thesis committee: Arnaud Bletterer (I3S Sophia Antipolis)
– Head of science, Inria center (for four years)
2017
joined the SMA Executive Board
– programme committee: ACM SIGGRAPH 2017
– programme committee: EUROGRAPHICS 2017
– programme committee: EUROGRAPHICS Star reports
– programme committee: EUROGRAPHICS Symposium on Geometry Processing
– programme committee: EG Workshop on Graphics and Cultural Heritage
– thesis reviewer: Giorgio Marcias (CNR Pisa, Italy)
– thesis reviewer: Claudio Calabrese (University Roma, Italy)
– thesis reviewer: Florian Caillaud (LIRIS Lyon)
– thesis reviewer: Dmitry Anisimov (Univ. Lugano)
– thesis reviewer: Yannick Masson (University Paris Est)
– thesis reviewer: Ana Vintescu (Telecom ParisTech)
– HDR committee: Maks Ovsjanikov (Ecole Polytechnique)

2016
– programme committee: ACM SIGGRAPH 2016
– programme committee: EUROGRAPHICS 2016
– programme committee: Geometric Modeling and Processing 2016
– programme committee: Shape Modeling International 2016
– programme committee: EUROGRAPHICS Symposium on Geometry Processing
– programme committee: EUROGRAPHICS Workshop on Graphics & Cultural Heritage
– thesis reviewer: Ludovic Blache (CReSTIC-SIC Reims-Châlons-Charleville)
– thesis reviewer: Ruqi Huang (Inria Saclay)
– thesis reviewer: Li Wang (Inria Grenoble)
– thesis comittee: Mael Rouxel-Labbé (Inria)

2015
– thesis reviewer: Jérémy Levallois (LIRIS)
– thesis committe: Rodolphe Vaillant (Université Paul Sabatier / University of Victoria)
– paper committee, EUROGRAPHICS Symposium on Geometry Processing (Graz, Austria)
– programme committee, Digital Heritage 2015
– thesis reviewer: Gilles-Philippe Paillé (Université de Montréal)

2014
– thesis reviewer: Louis Cuel (Université de Savoie)
– thesis committee: Jean luc Peyrot (CNRS-Université de Nice)
thesis reviewer: Alexandre Boul’ch (Ecole des Ponts ParisTech)
– Joined Horizon 2020 Advisory Group for Societal Challenge 6 ‘Europe in a changing world – Inclusive, Innovative and Reflective Societies.
– European paper co-chair, Geometric Modeling and Processing (Singapore)
– program committee, International Conference on 3D Computer Vision
– program committee, Shape Modeling International
thesis reviewer: Ricard Campos (University of Girona)
– joined the Steering Board of the EUROGRAPHICS Workshop on Graphics and Cultural Heritage
thesis reviewer: Henrik Zimmer (University of Aachen)
– program committe, EUROGRAPHICS Workshop on Graphics and Cultural Heritage
– paper committe, EUROGRAPHICS Workshop on Urban Data Modelling and Visualisation
– paper committee, EUROGRAPHICS Symposium on Geometry Processing (Cardiff, UK)
– thesis reviewer: Thierry Guillemot  (Telecom ParisTech)

2013
paper committee, ACM Virtual Reality International Conference
– local board member for Digital Heritage 2013
– thesis committee: Ricardo Uribe-Lobello (LIRIS, CNRS Lyon)
– thesis committee: Yannick Verdie (Inria)
– thesis reviewer: Thijs van Lankveld (Utrecht)
– thesis committee: Yannick Verdie (Inria)
– thesis committee: Adrien Maglo (Centrale Paris)
– thesis committee: Noura Faraj (Telecom ParisTech)
– joined board of Computer Aided Geometric Design
– paper committee, Shape Modeling International 2013
– paper committee, Eurographics Symposium on Geometry Processing (Genova, Italy)
– HDR thesis reviewer: Guillaume Lavoue (Universite de Lyon)

2012
– thesis reviewer, Nicolas Mellado, (Inria Bordeaux)
– thesis reviewer, David Bommes (RWTCH Aachen)
– invited speaker, MICCAI workshop on Mesh Processing in Medical Image Analysis (Nice).
– invited speaker, 3DIMPVT: 3D Imaging, Modeling, Processing, Visualization and Transmission (Zurich).
– paper committee, EUROGRAPHICS conference (Cagliari, Italy)
– paper committee, Eurographics Symposium on Geometry Processing (Talinn, Estonia)
– program committee, International Workshop on Point Cloud Processing (in conjunction with CVPR)
– invited speaker, Advances in Architectural Geometry (Paris).

2011
– thesis reviewer: Vincent Vidal (Universite de Lyon)
– HDR thesis reviewer: Raphaelle Chaine (Universite de Lyon)
– thesis committee: Patrick Mullen (Caltech)
– programme committee, VAST International Symposium on Virtual Reality, Archaeology and Cultural Heritage
programme committee, Sibgrapi 2011
– paper committee, Eurographics Symposium on Geometry Processing
– programme committee, Shape Modeling International
– thesis reviewer: Clement Courbet (Ecole Centrale Paris)
– thesis committee: Marcio Cabral (INRIA Sophia)
– thesis reviewer: Sahar Hassan (University of Grenoble)

2010
– joined board of Elsevier Graphical Models
– thesis reviewer: Julie Digne (ENS Cachan)
paper co-chair, Pacific Graphics 2010
– programme committee, Shape Modeling International
programme committee, ACM Symposium on Solid and Physical Modeling
– paper committee, Eurographics Symposium on Geometry Processing
– scientific committee: Advances in Architectural Geometry
– thesis committee: Mathieu Bredif (Telecom ParisTech and IGN, France)
– thesis reviewer: Thierry Stein (INRIA Rhone Alpes)

2009
– associate editor of the ACM Transactions on Graphics
short paper co-chair, Eurographics
programme committee, IMA Mathematics of Surfaces XIII conference.
– programme committee, SIAM/ACM Joint Conference on Geometric and Physical Modeling
– paper committee, Eurographics Symposium on Geometry Processing
– paper committee, Pacific Graphics
– thesis reviewer: Patrick Labatut (ENS Paris)
– thesis committee: Jean-Marie Favreau (University of Clermont-Ferrand)
– thesis committee: Jane Tournois (INRIA Sophia)

2008
paper co-chair, Eurographics Symposium on Geometry Processing
– paper committee, EUROGRAPHICS
– paper committee, Pacific Graphics
– paper committee, Shape Modeling International
– paper committee, ACm Symposium on Solid and Physical Modeling
– paper committee, Symposium on 3D Data Processing, Visualization and Transmission
– thesis reviewer: Christopher Dyken (University of Oslo)
– thesis reviewer: Johan Seland (University of Oslo)

2007
– paper committee, SIGGRAPH
– paper committee, CAD/Graphics
– paper committee, Pacific Graphics
– paper committee, Shape Modeling International
– paper committee, ACM Symposium on Solid and Physical Modeling
– paper committee, Eurographics Symposium on Geometry Processing

2006
paper committee, Pacific Graphics
– associate editor of the Visual Computer
– associate editor of Computers & Graphics
– part of the french ANR project GEOTOPAL
– thesis reviewer: Martin Marinov (RWTH Aachen)
– paper committee, ACM Symposium on Solid and Physical Modeling
paper committee, Eurographics Symposium on Geometry Processing
– paper committee, IEEE International Conference on Shape Modeling and Applications

2005
– Video and Multimedia presentation program committee, SOCG 2005
– paper committee, EUROGRAPHICS Symposium on Geometry Processing 2005
– paper committee, EUROGRAPHICS 2005
– paper committee, Pacific Graphics 2005
– thesis reviewer: Christian Rossl (MPII Saarbruck), Raphaele Balter (University of Rennes)
– member of thesis committee:Marie-Claude Frasson (University of Nice), Guillaume Lavoue (University of Lyon), Gabriel Peyre (Ecole Polytechnique)

2004-2006
– ACI GeoComp 2004-2007
AIM@SHAPE EU Network of Excellence (workpackage leader)

2004
– organizing co-chair, Second Eurographics Symposium on Geometry Processing 2004
– paper committee, Eurographics Symposium on Geometry Processing 2004
– paper committee, Eurographics 2004
– paper committee, Pacific Graphics 2004
– paper committee, Shape Modeling International 2004
– member of thesis committee: Frederic Payan

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CGAL Tutorial / GRAPES https://team.inria.fr/titane/cgal-tutorial-grapes/ Tue, 07 Dec 2021 10:59:07 +0000 https://team.inria.fr/titane/?p=1956 Continue reading

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Slides:
1.1 Getting started

1.2 Mesh generation

Labs on 2D and 3D meshing (unzip and read todo files) : link

Point sets : link

Meshes : link

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PhD position: Learning the geometric signature of CAD models https://team.inria.fr/titane/phd-position-learning-the-geometric-signature-of-cad-models/ Tue, 13 Apr 2021 12:36:16 +0000 https://team.inria.fr/titane/?p=1893 Continue reading

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More details can be found here

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PhD position: Parametric Shape Approximation from 3D data measurements https://team.inria.fr/titane/phd-position-parametric-shape-approximation-from-3d-data-measurements/ Mon, 12 Apr 2021 08:59:16 +0000 https://team.inria.fr/titane/?p=1890 Continue reading

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Details can be found here

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https://team.inria.fr/titane/1879-2/ Fri, 05 Mar 2021 19:01:40 +0000 https://team.inria.fr/titane/?p=1879 Continue reading

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Jean-Dominique Favreau: Stochastic approaches for Vector Graphics https://team.inria.fr/titane/jean-dominique-favreau-stochastic-approaches-for-vector-graphics/ Mon, 15 Jan 2018 11:50:52 +0000 https://team.inria.fr/titane/?p=1459 Continue reading

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Jean-Dominique will give a talk on Friday 26th of January from 10:30 to 11:30 in Byron Beige

Title: stochastic approaches for vector graphics

Abstract:

I will present a method to create vector cliparts from photographs. Our approach aims at reproducing two key properties of cliparts: they should be easily editable, and they should represent image content in a clean, simplified way. We observe that vector artists satisfy both of these properties by modeling cliparts with linear color gradients, which have a small number of parameters and approximate well smooth color variations. In addition, skilled artists produce intricate yet editable artworks by stacking multiple gradients using opaque and semi-transparent layers. Motivated by these observations, our goal is to decompose a bitmap photograph into a stack of layers, each layer containing a vector path filled with a linear color gradient. We cast this problem as an optimization that jointly assigns each pixel to one or more layer and finds the gradient parameters of each layer that best reproduce the input. Since a trivial solution would consist in assigning each pixel to a different, opaque layer, we complement our objective with a simplicity term that favors decompositions made of few, semi-transparent layers. However, this formulation results in a complex combinatorial problem combining discrete unknowns (the pixel assignments) and continuous unknowns (the layer parameters). We propose a Monte Carlo Tree Search algorithm that efficiently explores this solution space by leveraging layering cues at image junctions. We demonstrate the effectiveness of our method by reverse-engineering existing cliparts and by creating original cliparts from studio photographs.

I will also introduce Delaunay Point Processes, a framework for the extraction of geometric structures from images. Our approach simultaneously locates and groups geometric primitives (line segments, triangles) to form extended structures (line networks, polygons) for a variety of image analysis tasks. Similarly to traditional point processes, our approach uses Markov Chain Monte Carlo to minimize an energy that balances fidelity to the input image data with geometric priors on the output structures. However, while existing point processes struggle to model structures composed of inter-connected components, we propose to embed the point process into a Delaunay triangulation, which provides high-quality connectivity by construction. We further leverage key properties of the Delaunay triangulation to devise a fast Markov Chain Monte Carlo sampler. We demonstrate the flexibility of our approach on a variety of applications, including line network extraction, object contouring, and mesh-based image compression.

 

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