Interactive procedural simulation of paper tearing with sound

International audienceWe present a phenomenological model for the real-time simulation of paper tearing and sound. The model uses as input rotations of the hand along with the index and thumb of left and right hands to drive the position and orientation of two regions of a sheet of paper. The motion of the hands produces a cone shaped deformation of the paper and guides the formation and growth of the tear. We create a model for the direction of the tear based on empirical observation, and add detail to the tear with a directed noise model. Furthermore, we present a procedural sound synthesis method to produce tearing sounds during interaction. We show a variety of paper tearing examples and discuss applications and limitations

Real-time sound synthesis for paper material based on geometric analysis

International audienceIn this article, we present the first method to generate plausible sounds while animating crumpling virtual paper in real time. Our method handles shape-dependent friction and crumpling sounds which typically occur when manipulating or creasing paper by hand. Based on a run-time geometric analysis of the deforming surface, we identify resonating regions characterizing the sound being produced. Coupled to a fast analysis of the surrounding elements, the sound can be efficiently spatialized to take into account nearby wall or table reflectors. Finally, the sound is synthesized in real time using a pre-recorded database of frequency- and time-domain sound sources. Our synthesized sounds are evaluated by comparing them to recordings for a specific set of paper deformations

Real-time sound synthesis for paper material based on geometric analysis

International audienceIn this article, we present the first method to generate plausible sounds while animating crumpling virtual paper in real time. Our method handles shape-dependent friction and crumpling sounds which typically occur when manipulating or creasing paper by hand. Based on a run-time geometric analysis of the deforming surface, we identify resonating regions characterizing the sound being produced. Coupled to a fast analysis of the surrounding elements, the sound can be efficiently spatialized to take into account nearby wall or table reflectors. Finally, the sound is synthesized in real time using a pre-recorded database of frequency- and time-domain sound sources. Our synthesized sounds are evaluated by comparing them to recordings for a specific set of paper deformations

Synthèse de son de papier adaptée au mouvement et à la géométrie de la surface

National audienceNous présentons une méthode pour générer en temps réel un son plausible pour une animation d'un papier virtuel que l'on froisse. Pour cela, nous analysons l'animation géométrique de la surface du papier pour détecter les événements à l'origine de sons puis calculons géométriquement les zones du papier qui vibrent de part la propagation des ondes au travers de la surface. Le son résultant est ensuite synthétisé à partir à la fois d'extraits pré-enregistrés, et d'une synthèse procédurale, tenant compte de la forme géométrique de la surface et de sa dynamique. Nous validons nos résultats en comparant le son généré par notre modèle virtuel par rapport à des enregistrements réels pour un ensemble de cas d'animations caractéristiques. Abstract In this article, we present a method to generate plausible sounds for an animation of crumpling paper in real-time. We analyse the geometrical animation of the deformed surface to detect sound-producing events and compute the regions which resonate due to the propagation of the vibrations though the paper. The resulting sound is synthesized from both pre-recorded sounds and procedural generation taking into account the geometry of the surface and its dynamic. Our results are validated by comparing the generated sound of the virtual model with respect to real recording for a set of specific deformations

Interactive Detailed Cutting of Thin Sheets

International audienceIn this paper we propose a method for the interactive detailed cutting of deformable thin sheets. Our method builds on the ability of frame-based simulation to solve for dynamics using very few control frames while embedding highly detailed geometry - here an adaptive mesh that accurately represents the cut boundaries.Our solution relies on a non-manifold grid to compute shape functions that faithfully adapt to the topological changes occurring while cutting. New frames are dynamically inserted to describe new regions. We provide incremental mechanisms for updating simulation data, enabling us to achieve interactive rates. We illustrate our method with examples inspired by the traditional Kirigami artform

A Material Point Method for Elastoplasticity with Ductile Fracture and Frictional Contact

Simulating physical materials with dynamic movements to photo-realistic resolution has always been one of the most crucial and challenging topics in Computer Graphics. This dissertation considers large-strain elastoplasticity theory applied to the low-to-medium stiffness regime, with topological changes and codimensional objects incorporated. We introduce improvements to the Material Point Method (MPM) for two particular objectives, simulating fracturing ductile materials and incorporation of MPM and Lagrangian Finite Element Method (FEM).Our first contribution, simulating ductile fracture, utilizes traditional particle-based MPM [SSC13, SCS94] as well as the Lagrangian energy formulation of [JSS15] which uses a tetrahedron mesh, rather than particle-based estimation of the deformation gradient and potential energy. We model failure and fracture via elastoplasticity with damage. The material is elastic until its deformation exceeds a Rankine or von Mises yield condition. At that point, we use a softening model that shrinks the yield surface until it reaches the damage thresh- old. Once damaged, the material Lam ́e coefficients are modified to represent failed material. This approach to simulating ductile fracture with MPM is successful, as MPM naturally captures the topological changes coming from the fracture. However, rendering the crack surfaces can be challenging. We design a novel visualization technique dedicated to rendering the material’s boundary and its intersection with the evolving crack surfaces. Our approach uses a simple and efficient element splitting strategy for tetrahedron meshes to create crack surfaces. It employs an extrapolation technique based on the MPM simulation. For traditional particle-based MPM, we use an initial Delaunay tetrahedralization to connect randomly sampled MPM particles. Our visualization technique is a post-process and can run after the MPM simulation for efficiency. We demonstrate our method with several challenging simulations of ductile failure with considerable and persistent self-contact and applications with thermomechanical models for baking and cooking.Our second contribution, hybrid MPM–Lagrangian-FEM, aims to simulate elastic objects like hair, rubber, and soft tissues. It utilizes a Lagrangian mesh for internal force computation and a Eulerian grid for self-collision, as well as coupling with external materials. While recent MPM techniques allow for natural simulation of hyperelastic materials represented with Lagrangian meshes, they utilize an updated Lagrangian discretization and use the Eulerian grid degrees of freedom to take variations of the potential energy. It often coarsens the degrees of freedom of the Lagrangian mesh and can lead to artifacts. We develop a hybrid approach that retains Lagrangian degrees of freedom while still allowing for natural coupling with other materials simulated with traditional MPM, e.g., sand, snow, etc. Furthermore, while recent MPM advances allow for resolution of frictional contact with codimensional simulation of hyperelasticity, they do not generalize to the case of volumetric materials. We show that our hybrid approach resolves these issues. We demonstrate the efficacy of our technique with examples that involve elastic soft tissues coupled with kinematic skeletons, extreme deformation, and coupling with various elastoplastic materials. Our approach also naturally allows for two-way rigid body coupling

Synthèse de son de papier adaptée au mouvement et à la géométrie de la surface

National audienceNous présentons une méthode pour générer en temps réel un son plausible pour une animation d'un papier virtuel que l'on froisse. Pour cela, nous analysons l'animation géométrique de la surface du papier pour détecter les événements à l'origine de sons puis calculons géométriquement les zones du papier qui vibrent de part la propagation des ondes au travers de la surface. Le son résultant est ensuite synthétisé à partir à la fois d'extraits pré-enregistrés, et d'une synthèse procédurale, tenant compte de la forme géométrique de la surface et de sa dynamique. Nous validons nos résultats en comparant le son généré par notre modèle virtuel par rapport à des enregistrements réels pour un ensemble de cas d'animations caractéristiques. Abstract In this article, we present a method to generate plausible sounds for an animation of crumpling paper in real-time. We analyse the geometrical animation of the deformed surface to detect sound-producing events and compute the regions which resonate due to the propagation of the vibrations though the paper. The resulting sound is synthesized from both pre-recorded sounds and procedural generation taking into account the geometry of the surface and its dynamic. Our results are validated by comparing the generated sound of the virtual model with respect to real recording for a set of specific deformations

Storypath: A Powerful Tool for Engaging Children in Civic Education

This article explains why elementary school children need civic education, identifies common obstacles that frustrate efforts, then describes how the Storypath approach can provide all students with opportunities for powerful civic learning. An actual application in a culturally diverse fourth-grade classroom illustrates how children grappled with Seattle’s affordable housing issue as they created and enacted Storypath’s five components, namely setting, characters, context, critical incidents, and concluding event. It also demonstrates how Storypath effectively integrates social studies content, literacy skills, and social-emotional learning (SEL) through cooperative small-group episodes that produce meaningful and memorable lived experiences for students engaged in civic discourse and democratic decision-making. The article concludes by listing and explaining how Storypath nurtures multiple positive outcomes. These include (a) providing a feasible framework for organizing complex curricula; (b) stimulating imagination, motivation, investment, and commitment to learning; (c) engaging rigorous discussion for cognitive growth; (d) embodying authentic teaching and learning; (e) grounding effective cooperative learning; (f) supporting successful curriculum integration; (g) promoting accomplishment of national and state standards; (h) enabling individual differentiation for success; (i) developing civic capacity; (j) cultivating transfer of learning within and outside of classrooms; and (k) furthering the civic mission of schools

Virtual Reality Simulator for Training in Myringotomy with Tube Placement

Myringotomy refers to a surgical incision in the eardrum, and it is often followed by ventilation tube placement to treat middle-ear infections. The procedure is difficult to learn; hence, the objectives of this work were to develop a virtual-reality training simulator, assess its face and content validity, and implement quantitative performance metrics and assess construct validity. A commercial digital gaming engine (Unity3D) was used to implement the simulator with support for 3D visualization of digital ear models and support for major surgical tasks. A haptic arm co-located with the stereo scene was used to manipulate virtual surgical tools and to provide force feedback. A questionnaire was developed with 14 face validity questions focusing on realism and 6 content validity questions focusing on training potential. Twelve participants from the Department of Otolaryngology were recruited for the study. Responses to 12 of the 14 face validity questions were positive. One concern was with contact modeling related to tube insertion into the eardrum, and the second was with movement of the blade and forceps. The former could be resolved by using a higher resolution digital model for the eardrum to improve contact localization. The latter could be resolved by using a higher fidelity haptic device. With regard to content validity, 64% of the responses were positive, 21% were neutral, and 15% were negative. In the final phase of this work, automated performance metrics were programmed and a construct validity study was conducted with 11 participants: 4 senior Otolaryngology consultants and 7 junior Otolaryngology residents. Each participant performed 10 procedures on the simulator and metrics were automatically collected. Senior Otolaryngologists took significantly less time to completion compared to junior residents. Junior residents had 2.8 times more errors as compared to experienced surgeons. The senior surgeons also had significantly longer incision lengths, more accurate incision angles, and lower magnification keeping both the umbo and annulus in view. All metrics were able to discriminate senior Otolaryngologists from junior residents with a significance of p \u3c 0.002. The simulator has sufficient realism, training potential and performance discrimination ability to warrant a more resource intensive skills transference study

Skyler and Bliss

Hong Kong remains the backdrop to the science fiction movies of my youth. The city reminds me of my former training in the financial sector. It is a city in which I could have succeeded in finance, but as far as art goes it is a young city, and I am a young artist. A frustration emerges; much like the mould, the artist also had to develop new skills by killing off his former desires and manipulating technology. My new series entitled HONG KONG surface project shows a new direction in my artistic research in which my technique becomes ever simpler, reducing the traces of pixelation until objects appear almost as they were found and photographed. Skyler and Bliss presents tectonic plates based on satellite images of the Arctic. Working in a hot and humid Hong Kong where mushrooms grow ferociously, a city artificially refrigerated by climate control, this series provides a conceptual image of a imaginary typographic map for survival. (Laurent Segretier