Efficient modeling of entangled details for natural scenes

Proceedings of Pacific Graphics 2016 (Okinawa)International audienceDigital landscape realism often comes from the multitude of details that are hard to model such as fallen leaves, rock piles orentangled fallen branches. In this article, we present a method for augmenting natural scenes with a huge amount of details suchas grass tufts, stones, leaves or twigs. Our approach takes advantage of the observation that those details can be approximatedby replications of a few similar objects and therefore relies on mass-instancing. We propose an original structure, the GhostTile, that stores a huge number of overlapping candidate objects in a tile, along with a pre-computed collision graph. Detailsare created by traversing the scene with the Ghost Tile and generating instances according to user-defined density fields thatallow to sculpt layers and piles of entangled objects while providing control over their density and distribution

MALDI-MSI Towards Multimodal Imaging: Challenges and Perspectives

Multimodal imaging is a powerful strategy for combining information from multiple images. It involves several fields in the acquisition, processing and interpretation of images. As multimodal imaging is a vast subject area with various combinations of imaging techniques, it has been extensively reviewed. Here we focus on Matrix-assisted Laser Desorption Ionization Mass Spectrometry Imaging (MALDI-MSI) coupling other imaging modalities in multimodal approaches. While MALDI-MS images convey a substantial amount of chemical information, they are not readily informative about the morphological nature of the tissue. By providing a supplementary modality, MALDI-MS images can be more informative and better reflect the nature of the tissue. In this mini review, we emphasize the analytical and computational strategies to address multimodal MALDI-MSI.Imagerie multimodale combinant la spectroscopie Raman et la spectrométrie de masse appliquée à la tuberculos

Mass spectrometry imaging identifies palmitoylcarnitine as an immunological mediator during Salmonella Typhimurium infection

Salmonella Typhimurium causes a self-limiting gastroenteritis that may lead to systemic disease. Bacteria invade the small intestine, crossing the intestinal epithelium from where they are transported to the mesenteric lymph nodes (MLNs) within migrating immune cells. MLNs are an important site at which the innate and adaptive immune responses converge but their architecture and function is severely disrupted during S. Typhimurium infection. To further understand host-pathogen interactions at this site, we used mass spectrometry imaging (MSI) to analyse MLN tissue from a murine model of S. Typhimurium infection. A molecule, identified as palmitoylcarnitine (PalC), was of particular interest due to its high abundance at loci of S. Typhimurium infection and MLN disruption. High levels of PalC localised to sites within the MLNs where B and T cells were absent and where the perimeter of CD169+ sub capsular sinus macrophages was disrupted. MLN cells cultured ex vivo and treated with PalC had reduced CD4+CD25+ T cells and an increased number of B220+CD19+ B cells. The reduction in CD4+CD25+ T cells was likely due to apoptosis driven by increased caspase-3/7 activity. These data indicate that PalC significantly alters the host response in the MLNs, acting as a decisive factor in infection outcome

Biologically inspired simulation of livor mortis

We present a biologically motivated livor mortis simulation that is capable of modelling the colouration changes in skin caused by blood pooling after death. Our approach consists of a simulation of post mortem blood dynamics and a layered skin shader that is controlled by the haemoglobin and oxygen levels in blood. The object is represented by a layered data structure made of a triangle mesh for the skin and a tetrahedral mesh on which the blood dynamics are simulated. This allows us to simulate the skin discolouration caused by livor mortis, including early patchy appearance, fixation of hypostasis and pressure induced blanching. We demonstrate our approach on two different models and scenarios and compare the results to real world livor mortis photographic examples

Modélisation et simulation des scènes naturelles complexes

In this thesis, we address the modelling realistic natural sceneries. We focus on the modelling of details and their distribution in a complex scene. Details have a great impact over the overall realism of the final scene. Our approach consists in modeling details such as mushrooms, lichens, leaves or fractures and storing them in an atlas of shapes. Those details are distributed in the scene according to specific physically and biologically based dispersion and propagation algorithms, which are controlled by the parameters of the environment such as the wetness, the temperature or the amount of direct and indirect lighting. Our approach enables us to add a vast variety of details without the burden of editing them by hand.Dans cette thèse, nous abordons le problème de la modélisation de scènes naturelles réalistes. Nous nous sommes plus particulièrement intéressés à la modélisation des détails et à leur répartition. Ces deux aspects jouent un rôle fondamental sur le réalisme des scènes virtuelles. L’approche que nous proposons dans cette thèse repose sur la définition de trois éléments clés : un atlas de formes élémentaires, un algorithme de dispersion et un algorithme de propagation. L’atlas est composé des briques de bases utilisées pour la génération de la géométrie des détails. L’algorithme de propagation, quant à lui, décrit comment ces éléments vont se combiner pour former l’objet final. Enfin, l’algorithme de dispersion définit leur répartition dans la scène. L’approche que nous décrivons permet également de prendre en compte les caractéristiques de l’environnement lors des étapes de placement et de propagation. Nous avons appliqué cette approche à trois éléments que l’on rencontre couramment dans la nature : les lichens, les feuilles et les fissures

Modeling cracks and fractures

International audienceThis paper presents an interactive method for modeling cracks and fractures over a variety of materials such as glass, metal, wood, and stone. Existing physically based techniques are computationally demanding and lack control over the fracture propagation. Our approach consists in editing 2D fracture pattern and profile curves which are stored in an atlas according to material type. The fracture model is then automatically mapped onto the surface of the object and fractures are created by carving out a procedurally generated swept volume. Because the objects need not be voxelized or tetrahedralized as with physically based techniques, we are not limited in resolution when creating the geometry of cracks, which enables us to model small or very thin fractures

Modélisation de détails dans les scènes naturelles

19ièmes Journées de l'Association Française d'Informatique Graphique (AFIG).no abstrac

Realistic Urban Road Network Modelling From GIS Data

International audienceStarting from GIS data, which are sampled and often inaccurate, this paper presents a method to reconstruct urban road surfaces respecting important geometric constraints selected from civil engineering. We propose a mathematical road surface model based upon road axes and properties. In addition, we introduce a process to produce a mesh representing the roads and the terrain so that roads and terrain match. Experiments and compelling results prove the efficiency of our framework

Operational theater generation by a descriptive language

The authors acknowledge support by SopraSteria and French ANRT "Association Nationale de Recherche et Technologie" under CIFRE n° 2020/0364. The authors also thank the GrandLyon and IGN open data for their resources.3D landscapes generation is an interdisciplinary field that requires expertise in both computer graphics and ge ographic informations systems (GIS). It is a complex and time-consuming process. In this paper, we present a new approach to simplify 3D environment generation process, by creating a go-between data-model containing a list of available source data and steps to use them. To feed the data-model, we introduce a formal language that describes the process’s sequence. We propose an adapted format, designed to be human-readable and machine readable, allowing for easy creation and modification of the scenery. We demonstrate the utility of our approach by implementing a prototype system to generate 3D landscapes with a use-case fit for multipurpose simulation. Our system takes a description as input and outputs a complete 3D environment, including terrain and feature elements such as buildings created by chosen geometrical process. Experiments show that our approach reduces the time and effort required to generate a 3D environment, making it accessible to a wider range of users without extensive knowledge of GIS. In conclusion, our custom language and implementation provide a simple and effective solution to the complexity of 3D terrain generation, making it a valuable tool for users in the are