# Foreword to the special section on Shape Modeling
## International 2023 (SMI2023)

Georges-Pierre Bonneau, Ligang Liu, Michela Mortara

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Georges-Pierre Bonneau, Ligang Liu, Michela Mortara. Foreword to the special section on Shape Modeling International 2023 (SMI2023). Computers and Graphics, 115, pp.A6-A9, 2023, 10.1016/j.cag.2023.10.008 . hal-04322799

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# Foreword to the Special Section on Shape Modeling International 2023 (SMI2023)

Georges-Pierre Bonneau<sup>a,b,c</sup>, Ligang Liu<sup>d</sup>, Michela Mortara<sup>e</sup>

This Special Section of Computers & Graphics (C&G), features the full papers presented at the Shape Modeling International 2023 conference — SMI 2023 (https://smiconf.github.io/2023/). After the COVID pandemic, the desire was strong to bring the community together again in person. The conference was organised by CNR-IMATI and hosted at the DAD – Department of Architecture and Design - in Genova, Italy, from 4 to 6 July 2023. This year SMI was co-located with the Symposium on Physical and Solid Modeling (SPM 2023), Geometric Modeling and Processing (GMP2023), the SIAM Conference on Computational Geometric Design (GD2023), and the EG Symposium on Geometry Processing (SGP2023) within the International Geometry Summit 2023, 3-7 July 2023. Overall, the Geometry Summit gathered more than three hundred researchers from all over the world.

Shape Modeling International provides yearly an international forum for the dissemination of new mathematical theories and computational techniques for modeling, simulating, and processing digital representations of shapes and their properties to a community of researchers, developers, students, and practitioners across a wide range of fields. This year, the call for paper has been enriched to explicitly address new emerging topics related to digital shapes, like deep geometric learning and 3D digital twins. The invited speakers, Professor Angela Dai and Professor Thomas Kolbe, both from the *TUM, Technical University of Munich*, accordingly, provided interesting insights on Learned Parametric 3D Shape Models and on Spatio-Semantic Modeling for Urban Digital Twins, respectively.

SMI2023 has assigned two prestigious prizes, namely, the Tosiyasu L. Kunii distinguished researcher award, presented to Prof. Wenping Huang from the *Department of Computer Science & Engineering at Texas A&M University*, and the SMI young investigator award, presented to Dr. Etienne Corman from the *CNRS - LORIA lab* in Nancy, France. Furthermore, this year the Alexander Pasko service award has been estab-

lished, to recognise people who made significant contributions to the organization of SMI conferences. This first edition of the prize has been presented to Dr. Michela Spagnuolo from CNR-IMATI, Italy, for her long-standing support to Shape Modeling International, besides her scientific contributions to the field.

The full paper submission track followed a 2-stage double-blind review process. Each paper was assessed by 4 reviewers on average. Of the 61 papers submitted to the full paper track 18 were accepted and are published in this Special Section of Computers & Graphics. Contributions came from all over the world, with a significant amount of papers from China, France, Italy and the United States. 6 papers applied and received the Replicability Badge issued by the *Graphics Replicability Stamp Initiative (GRS I)*. Besides the 18 reviewed papers, SMI2023 invited for oral presentation 10 papers from C&G; of these, 2 accepted the invitation and has been presented at the conference: *Saliency Detection for Large-Scale Mesh Decimation*, by Rafael Kuffner dos Anjos, Richard Andrew Roberts, Benjamin Allen, Joaquim Jorge and Ken Anjyo, presented by Professor Jorge from the *Institute for Computer and Systems Engineering INESC-ID* in Portugal, and *An interactive sketch-based CAD interface realizing geometrical and topological editing across multiple objects based on fuzzy logic* by Tomohiko Ito, Teruyoshi Kaneko, Yoshiki Tanaka and Sato Saga, presented by Professor Saga from the *Muroran Institute of Technology* in Japan.

SMI2023 received financial sponsorship from Elsevier for the *Best Paper Award* and two *Honourable Mentions*. After all the presentations, the SMI award committee selected the best paper among those who have obtained the replicability stamp, to encourage researchers to publish their code and make it available to the community. The SMI2023 best paper award has been presented to Mattéo Clémot and Julie Digne for the paper *Neural skeleton: implicit neural representation away from the surface*, and honourable mentions went to Guillaume Gisbert, Raphaëlle Chaine and David Coeurjolly for the paper *Inpainting Holes in Folded Fabric Meshes* and to Felix Dellinger, Xinye Li and Hui Wang for the paper *Discrete Orthogonal Structures*.

Selected full papers are available at https://www.sciencedirect.com/journal/computers-and-graphics/

<footnote><sup>a</sup>Université Grenoble Alpes, France</footnote>

<footnote><sup>b</sup>Laboratoire Jean Kuntzmann, France</footnote>

<footnote><sup>c</sup>INRIA Rhône-Alpes, France</footnote>

<footnote><sup>d</sup>Graphics& Geometric Computing Laboratory, School of Mathematical Sciences, University of Science and Technology of China</footnote>

<footnote><sup>e</sup>Istituto di Matematica Applicata e Tecnologie Informatiche E. Magenes' - CNR, Italy</footnote>

<footnote>e-mail: georges-pierre.bonneau@inria.fr (Georges-Pierre Bonneau), lgliu@ustc.edu.cn (Ligang Liu), michela.mortara@cnr.it (Michela Mortara)</footnote>
**special-issues.** These works cover a variety of topics, including geometric modelling and processing, curves and surfaces, object and scene reconstruction and understanding. All accepted papers and invited talks were orally presented in person and grouped into the following themed sessions:

## Geometry Processing

* Inpainting Holes In Folded Fabric Meshes, Guillaume Gisbert, Raphaëlle Chaine and David Coeurjolly, [1]. **[Honourable Mention and Replicability Stamp]**

* Crossing-Free Paths in the Square Grid, Lidija Comic and Paola Magillo, [2]. **[Replicability Stamp]**

* Exploration of 3D Motorcycle Complexes from Hexahedral Meshes, Erkan Gunpinar, Marco Livesu and Marco Attene, [3].

* Saliency Detection for Large-Scale Mesh Decimation, Rafael Kuffner dos Anjos, Richard Andrew Roberts, Benjamin Allen, Joaquim Jorge and Ken Anjyo, [4]. **[invited from C&G]**

## Scene Understanding

* Analyzing Part Functionality via Multi-modal Latent Space Embedding and Interweaving, Jiahao Cui, Shuai Li, Fei Hou, Aimin Hao and Hong Qin, [5]. **[Replicability Stamp]**

* Lightweight Integration of 3D Features to Improve 2D Image Segmentation, Olivier Pradelle, Raphaëlle Chaine, David Wendland and Julie Digne, [6].

## Meshless and Implicits

* Neural Skeleton: Implicit Neural Representation Away From The Surface, Mattéo Clémot and Julie Digne, [7]. **[Best Paper Award and Replicability Stamp]**

* Forward Inclusion Functions for Ray-Tracing Implicit Surfaces, Melike Aydinlilar and Cédric Zanni, [8].

* Meshless Power Diagrams, Yanyang Xiao, Juan Cao, Shaoping Xu and Zhonggui Chen, [9]. **[Replicability Stamp]**

* Learning Neural Implicit Representations with Surface Signal Parameterizations, Yanran Guan, Andrei Chubarau, Ruby Rao and Derek Nowrouzezahrai, [10].

## Curves and Surfaces

* Discrete Orthogonal Structures, Felix Dellinger, Xinye Li and Hui Wang, [11]. **[Honourable Mention]**

* Constrained Modeling of Multi-sided Patches, Péter Salvi, Márton Vaitkus and Tamás Várady, [12].

* A Skinning Technique for Modeling Artistic Disk B-spline Shapes, Kinga Kruppa, Roland Kunkli and Miklós Hoffmann, [13].

* Curvature Monotonicity Evaluation Functions on Rational Bézier Curves, Takafumi Saito and Norimasa Yoshida, [14].

## Geometry and Matter

* A Modular Approach for Creation of Any Bi-Axial Woven Structure with Congruent tiles, Tolga Yildiz, Ergun Akleman, Matthew Ebert and Vinayak Krishnamurthy, [15]. **[Replicability Stamp]**

* Bending the Light: Next Generation Anamorphic Sculptures, Louis Pratt, Andrew Johnston and Nico Pietroni, [16].

## Sketch-based CAD and Surface Reconstruction

* Automatic 3D CAD Models Reconstruction from 2D Orthographic Drawing, Chao Zhang, Romain Pinquié, Arnaud Poiette, Gregorio Carasi, Henri Gautier De Charnace and Jean-Philippe Pernot, [17].

* Multi-Grid Representation with Field Regularization for Self-Supervised Surface Reconstruction from Point Clouds, Chuan Jin, Tieru Wu and Junsheng Zhou, [18].

* Contact-conditioned Hand-held Object Reconstruction from Single-view Images, Xiaoyuan Wang, Yang Li, Adnane Boukhayma, Changbo Wang and Marc Christie, [19].

* An Interactive Sketch-based CAD Interface Realizing Geometrical and Topological Editing Across Multiple Objects Based on Fuzzy Logic, Tomohiko Ito, Teruyoshi Kaneko, Yoshiki Tanaka and Sato Saga, [20]. **[Invited from C&G]**

## Keynotes

* Learned Parametric 3D Shape Models, Professor Angela Dai, School of Computation, Information and Technology, Technische Universität München (TUM), Germany

* Spatio-Semantic Modeling for Urban Digital Twins, Professor Thomas Kolbe, School of Engineering and Design, Technische Universität München (TUM), Germany

We would like to thank the 75 IPC members and the invited external reviewers for their reviewing efforts, which helped us to create a high-quality program and led to the success of this Special Section. We are grateful to all session chairs Daniela Giorgi, Amir Vaxman, Ergun Akleman, Gershon Elber, ChiaraEva Catalano, and Raphaëlle Chaine for their caring and timely direction of the SMI sessions; to the conference co-chairs Giuseppe Patanè, Jorg Peters and Hui Huang; to the communication chairs Silvia Biasotti and Yang Liu for their support and for the timely management of the conference web site; to Ergun Akleman who supervised the SMI organization and to Joaquim Jorge, editor in chief of C&G and to the whole Elsevier C&G Team for making this Special Section possible. Finally, we deeply thank all authors for their interest and support to SMI 2023 and the speaker for making SMI2023 a lively and exiting conference.

## International Program Committee

Valery Adzhiev, Bournemouth University, England

Marco Attene, CNR-IMATI, Italy

Gill Barequet, Technion Israel Institute of Technology, Israel

Loic Barthe, Université de Toulouse, France

Alexander Belyaev, Heriot-Watt University, UK

Pengbo Bo, Harbin Institute of Technology, P.R. China

Adrien Bousseau, Inria Sophia-Antipolis, France

Marcel Campen, Osnabrück University, Germany

Juan Cao, Xiameng University, P.R. China

Chiara Eva Catalano, CNR-IMATI, Italy

Raphaëlle Chaine, Université de Lyon, France

Zhonggui Chen, Xiameng University, P.R. China

Renjie Chen, University of Science and Technology of China, P.R. China

Edward Chien, MIT, USA

Tao Du, Tsinghua University, P.R. China

Jeremie Dumas, Adobe Research, USA

Ye Duan, University of Missouri, USA

Gershon Elber, Technion, Israel
Bianca Falcidieno, CNR-IMATI, Italy

Leila De Floriani, University of Maryland, USA

Hongbo Fu, City University of Hong Kong, P.R. China

Xiaoming Fu, University of Science and Technology of China, P.R. China

Eric Galin, University of Lyon, France

Lin Gao, Chinese Academy of Sciences, P.R. China

Yotam Gingold, George Mason University, USA

Daniela Giorgi, CNR-ISTI, Italy

Eric Guerin, INSA de Lyon, France

Jianwei Guo, Chinese Academy of Sciences, P.R. China

Fazhi He, Wuhan University, P.R. China

Franck Hetroy-Wheeler, University of Strasbourg, France

Klaus Hildebrandt, TU Delft, Netherlands

Haibin Huang, Kwai Inc., USA

Kai Hormann, Università della svizzera italiana, Switzerland

Jin Huang, Zhejiang University, P.R. China

Ioannis Ivrissimtzis, Durham University, UK

Xiaohong Jia, Chinese Academy of Sciences, P.R. China

Bert Jüttler, Johannes Kepler University, Austria

Takashi Kanai, University of Tokyo, Japan

Myung-Soo Kim, Seoul National University, Korea

Hamid Laga, Murdoch University, Australia

Xin Li, Texas A&M University, USA

Zhouhui Lian, Peking University, P.R. China

Hongwei Lin, Zhejiang University, P.R. China

Peter Lindstrom, Lawrence Livermore National Laboratory, USA

Lin Lu, Shandong University, P.R. China

Chongyang Ma, Kuaishou Technology, P.R. China

Luigi Malomo, CNR-ISTI, Italy

Claudio Mancinelli, University of Genova, Italy

Martin Marinov, Autodesk, USA

Nicolas Mellado, CNRS IRIT, France

Serena Morigi, University of Bologna, Italy

Ahmad Nasri, Boulder Graphics LLC, USA

Stefan Ohrhallinger, Vienna University of Technology, Austria

Yutaka Ohtake, University of Tokyo, Japan

Amal Dev Parakkat, Institut Polytechnique de Paris, France

Konrad Polthier, Freie Universitat Berlin, Germany

Andreas Scalas, CNR-IMATI, Italy

Hong Qin, Stony Brook University, USA

Camille Schreck, INRIA Nancy, France

Carlo Sequin, UC Berkeley, USA

Liyong Shen, Chinese Academy of Sciences, P.R. China

Zhenyu Shu, Zhejiang University, P.R. China

Karan Singh, University of Toronto, Canada

Keke Tang, Guangzhou University, P.R. China

Daniel Thalmann, Swiss Federal Institute of Technology, Switzerland

Georg Umlauf, HTWG Konstanz, Germany

Amir Vaxman, The University of Edinburgh, UK

Remco Veltkamp, Utrecht University, the Netherlands

Pengshuai Wang, Peking University, P.R. China

Weiming Wang, Dalian University of Technology, P.R. China

Kui Wu, Tencent North America, USA

Tieru Wu, Jilin University, P.R. China

Kai Xu, National University of Defense Technology, P.R. China

Gang Xu, Hangzhou Dianzi University, P.R. China

Qiang Zou, Zhejiang University, P.R. China

## External Reviewers

Simone Cammarasana, CNR-IMATI, Italy

Sumita Dahiya, Netaji Subhas University of Technology, India

Haitham Fadina, Technion, Israel Institute of Technology, Israel

Stefanie Hahmann, INRIA, G-INP, France

Ulrich Reitebuch, Freie Universität Berlin, Germany

Chiara Romanengo, CNR-IMATI, Italy

Jakub Rondomansk, Freie Universität Berlin, Germany

Amani Shhadi, Technion, Israel Institute of Technology, Israel

Yawen Shi,

Tommaso Sorgente, CNR-IMATI, Italy

Alexander Tereshin,

Jianpeng Wu,

Q Youn Hong, Hanyang University at Ansan, Republic of Korea

Eric Zimmermann, Freie Universität Berlin, Germany

Qianfang Zou.

## References

[1] Gisbert, G, Chaine, R, Coeurjolly, D. Inpainting holes in folded fabric meshes. Computers Graphics 2023;114:201-209. URL: https://www.sciencedirect.com/science/article/pii/S0097849323000808. doi:https://doi.org/10.1016/j.cag.2023.05.025.

[2] Čomić, L, Magillo, P. Crossing-free paths in the square grid. Computers Graphics 2023;114:296-305. URL: https://www.sciencedirect.com/science/article/pii/S0097849323001115. doi:https://doi.org/10.1016/j.cag.2023.06.015.

[3] Gunpinar, E, Livesu, M, Attene, M. Exploration of 3d motorcycle complexes from hexahedral meshes. Computers Graphics 2023;114:105-115. URL: https://www.sciencedirect.com/science/article/pii/S0097849323000948. doi:https://doi.org/10.1016/j.cag.2023.06.005.

[4] Kuffner dos Anjos, R, Roberts, RA, Allen, B, Jorge, J, Anjyo, K. Saliency detection for large-scale mesh decimation. Computers Graphics 2023;111:63-76. URL: https://www.sciencedirect.com/science/article/pii/S0097849323000134. doi:https://doi.org/10.1016/j.cag.2023.01.012.

[5] Cui, J, Li, S, Hou, F, Hao, A, Qin, H. Analyzing part functionality via multi-modal latent space embedding and interweaving. Computers Graphics 2023;115:1-12. URL: https://www.sciencedirect.com/science/article/pii/S0097849323001267. doi:https://doi.org/10.1016/j.cag.2023.06.031.

[6] Pradelle, O, Chaine, R, Wendland, D, Digne, J. Lightweight integration of 3d features to improve 2d image segmentation. Computers Graphics 2023;114:326-336. URL: https://www.sciencedirect.com/science/article/pii/S0097849323000936. doi:https://doi.org/10.1016/j.cag.2023.06.004.

[7] Clémot, M, Digne, J. Neural skeleton: Implicit neural representation away from the surface. Computers Graphics 2023;114:368-378. URL: https://www.sciencedirect.com/science/article/pii/S0097849323001085. doi:https://doi.org/10.1016/j.cag.2023.06.012.
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[9] Xiao, Y, Cao, J, Xu, S, Chen, Z. Meshless power diagrams. Computers Graphics 2023;114:247-256. URL: https://www.sciencedirect.com/science/article/pii/S0097849323001073 doi:https://doi.org/10.1016/j.cag.2023.06.014.

[10] Guan, Y, Chubarau, A, Rao, R, Nowrouzezahrai, D. Learning neural implicit representations with surface signal parameterizations. Computers Graphics 2023;114:257-264. URL: https://www.sciencedirect.com/science/article/pii/S0097849323001103 doi:https://doi.org/10.1016/j.cag.2023.06.013.

[11] Dellinger, F, Li, X, Wang, H. Discrete orthogonal structures. Computers Graphics 2023;114:126-137. URL: https://www.sciencedirect.com/science/article/pii/S0097849323000791 doi:https://doi.org/10.1016/j.cag.2023.05.024.

[12] Salvi, P, Vaitkus, M, Várady, T. Constrained modeling of multi-sided patches. Computers Graphics 2023;114:86-95.
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[13] Kruppa, K, Kunkli, R, Hoffmann, M. A skinning technique for modeling artistic disk b-spline shapes. Computers Graphics 2023;115:96-106.
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[14] Saito, T, Yoshida, N. Curvature monotonicity evaluation functions on rational bézier curves. Computers Graphics 2023;114:219-228.
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[15] Yildiz, T, Akleman, E, Krishnamurthy, V, Ebert, M. A modular approach for creation of any bi-axial woven structure with congruent tiles. Computers Graphics 2023;114:357-367.
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[16] Pratt, L, Johnston, A, Pietroni, N. Bending the light: Next generation anamorphic sculptures. Computers Graphics 2023;114:210-218.
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[17] Zhang, C, Pinquié, R, Polette, A, Carasi, G, De Charnace, H, Pernot, JP. Automatic 3d cad models reconstruction from 2d orthographic drawings. Computers Graphics 2023;114:179-189.
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[18] Jin, C, Wu, T, Zhou, J. Multi-grid representation with field regularization for self-supervised surface reconstruction from point clouds. Computers Graphics 2023;114:379-386.
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[19] Wang, X, Li, Y, Boukhayma, A, Wang, C, Christie, M. Contact-conditioned hand-held object reconstruction from single-view images. Computers Graphics 2023;114:150-157.
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[20] Ito, T, Kaneko, T, Tanaka, Y, Saga, S. An interactive sketch-based cad interface realizing geometrical and topological editing across multiple objects based on fuzzy logic. Computers Graphics 2022;103:153-167.
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**Georges-Pierre Bonneau** is Professor of Computer Science at Université Grenoble Alpes. GP Bonneau received his MS degree in Mathematics from the Ecole Normale Supérieure de Cachan, France, the DEA in Numerical Analysis at the University of Paris VI, France, and the PhD degree in Computer

Science from the University of Kaiserslautern, Germany, in 1993. His research centres on Computer Aided Geometric Design, Computational Fabrication, Data Visualization and Visual perception for Computer graphics. He was co-organizer of two Dagstuhl seminars on Scientific Visualization. He is a member of the Editorial Board Committee of Computer Aided Design, Elsevier.

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**Ligang Liu** is Professor of Mathematical Sciences at the University of Science and Technology of China. He received his PhD from Zhejiang University in 2001. He once worked at Microsoft Research Asia, Zhejiang University, and visited Harvard University. His research interests include computer graphics and geometry processing. He serves as the

associated editors for journals including IEEE TVCG, CAGD, C&G, etc. He served as the conference co-chairs and the program co-chairs of many conferences. He serves as the steering committee member of GMP and the secretary of Asiographics Association.

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**Michela Mortara** is Senior Researcher at the Institute of Applied Mathematics and Information Technologies (IMATI) of the Italian National Research Council (CNR). Her research interests are in Shape Modelling and Analysis, Cultural Heritage and Serious Games. More recently, she has been working on 3D modelling for

Geosciences, with applications to environmental monitoring and interpretation of geological structures, and on Urban Intelligence, to develop digital twins of Matera and Catania in Italy. She is member of the Editorial Board of The Visual Computer, The International Journal of Serious Games and recently Computers&Graphics.